Effect of treatment with cyclophosphamide in low doses upon the onset of delayed type hypersensitivity in mice chronically infected with Trypanosoma cruzi: involvement of heart interstitial dendritic cells

Acute infection with Trypanosoma cruzi results in intense myocarditis, which progresses to a chronic, asymptomatic indeterminate form. The evolution toward this chronic cardiac form occurs in approximately 30% of all cases of T. cruzi infection. Suppression of delayed type hypersensitivity (DTH) has been proposed as a potential explanation of the indeterminate form. We investigated the effect of cyclophosphamide (CYCL) treatment on the regulatory mechanism of DTH and the participation of heart interstitial dendritic cells (IDCs) in this process using BALB/c mice chronically infected with T. cruzi. One group was treated with CYCL (20 mg/kg body weight) for one month. A DTH skin test was performed by intradermal injection of T. cruzi antigen (3 mg/mL) in the hind-footpad and measured the skin thickness after 24 h, 48 h and 72 h. The skin test revealed increased thickness in antigen-injected footpads, which was more evident in the mice treated with CYCL than in those mice that did not receive treatment. The thickened regions were characterised by perivascular infiltrates and areas of necrosis. Intense lesions of the myocardium were present in three/16 cases and included large areas of necrosis. Morphometric evaluation of lymphocytes showed a predominance of TCD8 cells. Heart IDCs were immunolabelled with specific antibodies (CD11b and CD11c) and T. cruzi antigens were detected using a specific anti-T. cruzi antibody. Identification of T. cruzi antigens, sequestered in these cells using specific anti-T. cruzi antibodies was done, showing a significant increase in the number of these cells in treated mice. These results indicate that IDCs participate in the regulatory mechanisms of DTH response to T. cruzi infection.

Rational design of diagnostic and vaccination strategies for tuberculosis

The development of diagnostic tests which can readily differentiate between vaccinated and tuberculosis-infected individuals is crucial for the wider utilization of bacillus Calmette-Guérin (BCG) as vaccine in humans and animals. BCG_0092 is an antigen that elicits specific delayed type hypersensitivity reactions similar in size and morphological aspects to that elicited by purified protein derivative, in both animals and humans infected with the tubercle bacilli. We carried out bioinformatics analyses of the BCG_0092 and designed a diagnostic test by using the predicted MHC class I epitopes. In addition, we performed a knockout of this gene by homologous recombination in the BCG vaccine strain to allow differentiation of vaccinated from infected individuals. For that, the flanking sequences of the target gene (BCG_0092)were cloned into a suicide vector. Spontaneous double crossovers, which result in wild type revertants or knockouts were selected using SacB. BCG_0092 is present only in members of the Mycobacterium tuberculosis complex. Eight predicted MHC class I epitopes with potential for immunological diagnosis were defined, allowing the design of a specific diagnostic test. The strategy used to delete the (BCG_0092) gene from BCG was successful. The knockout genotype was confirmed by PCR and by Southern blot. The mutant BCG strain has the potential of inducing protection against tuberculosis without interfering with the diagnostic test based on the use of selected epitopes from BCG_0092.

Effect of lipoarabinomannan from Mycobacterium avium subsp avium in Freund’s incomplete adjuvant on the immune response of cattle

The aim of the present study was to determine whether lipoarabinomannan (LAM), in combination with Freund’s incomplete adjuvant (FIA), was able to improve cell-mediated and antibody-mediated immune responses against ovalbumin (OVA) in cattle. Twenty-three calves were assigned to four treatment groups, which were subcutaneously immunized with either OVA plus FIA, OVA plus FIA and LAM from Mycobacterium avium subsp avium, FIA plus LAM, or FIA alone. Lymphoproliferation, IFN-γ production and cell subpopulations on peripheral blood mononuclear cells before and 15 days after treatment were evaluated. Delayed hypersensitivity was evaluated on day 57. Specific humoral immune response was measured by ELISA. Inoculation with LAM induced higher levels of lymphoproliferation and IFN-γ production in response to ConA and OVA (P < 0.05). Specific antibody titers were similar in both OVA-immunized groups. Interestingly, our results showed that the use of LAM in vaccine preparations improved specific cell immune response evaluated by lymphoproliferation and IFN-γ production by at least 50 and 25 percent, respectively, in cattle without interfering with tuberculosis and paratuberculosis diagnosis.

Safety and skin delayed-type hypersensitivity response in vervet monkeys immunized with Leishmania donovani sonicate antigen delivered with adjuvants / Segurança e reação de hipersensibilidade tardia na pele de macacos vervet imunizados com antígeno sonicado de Leishmania donovani junto com adjuvantes

In this study, we report on the safety and skin delayed-type hypersensitivity (DTH), responses of the Leishmania donovani whole cell sonicate antigen delivered in conjunction with alum-BCG (AlBCG), Montanide ISA 720 (MISA) or Monophosphoryl lipid A (MPLA) in groups of vervet monkeys. Following three intradermal injections of the inoculums on days 0, 28 and 42, safety and DTH responses were assessed. Preliminary tumor necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ) levels were also measured and these were compared with DTH. Only those animals immunized with alum-BCG reacted adversely to the inoculum by producing ulcerative erythematous skin indurations. Non-parametric analysis of variance followed by a post-test showed significantly higher DTH responses in the MISA+Ag group compared with other immunized groups (p < 0.001). The MPLA+Ag group indicated significantly lower DTH responses to the sonicate antigen compared with the AlBCG+Ag group. There was a significant correlation between the DTH and cytokine responses (p < 0.0001). Based on this study we conclude that Leishmania donovani sonicate antigen containing MISA 720 is safe and is associated with a strong DTH reaction following immunization.

Neste estudo reportamos segurança e resposta de hipersensibilidade tardia (DTH) do antígeno sonicado de células totais de Leishmania donovani introduzidos juntamente com alume-BCG (AIBCG) Montanide ISA 720 (MISA) ou lípide A monofosforilado (MPLA) em grupos de macacos vervet. Depois de três injeções intradérmicas do inóculo nos dias 0, 28 e 42 segurança e resposta DTH foram avaliados. Preliminarmente níveis de fator de necrose tumoral alfa (TNF-α) e interferon gama (IFN-γ) foram também medidos e comparados com o DTH. Somente os animais imunizados com alume-BCG reagiram de maneira diversa ao inóculo produzindo indurações ulceradas e eritematosas na pele. Análise não paramétrica de variação seguida por um teste posterior mostraram resposta significantemente mais alta do DTH no grupo MISA + Ag quando comparado com outros grupos imunizados (p < 0.001). O grupo MPLA + Ag demonstrou resposta DTH significantemente menor do antígeno sonicado comparado com o grupo AIBCG + Ag. Houve correlação significante entre o DTH e a resposta às citocinas (p < 0.0001). Baseados neste estudo concluímos que o antígeno sonicado de Leishmania donovani contendo MISA 720 é seguro e está associado com forte reação DTH após imunização.

Delayed-type hypersensitivity skin test responses to PPD and other antigens among BCG-vaccinated HIV-1-infected and healthy children and adolescents / Resposta de testes de hipersensibilidade tardia utilizando PPD e outros antígenos em crianças e adolescentes saudáveis e infectados pelo HIV-1 e vacinados com BCG

INTRODUCTION: Among HIV-1-infected patients, CD4+ T cell counts are well-established markers of cell-mediated immunity. Delayed-type hypersensitivity (DTH) skin tests can be used to evaluate in vivo cell-mediated immunity to common antigens. METHODS: DTH responses to tuberculin purified protein derivative (PPD), sporotrichin, trichophytin, candidin and streptokinase/streptodornase antigens were assessed. Thirty-six HIV-1-infected children/adolescents and 56 age- and sex-matched HIV-1/HIV-2-seronegative participants were tested. All participants had a BCG scar. Fisher's exact test was used to evaluate significant differences between groups (p<0.05). RESULTS: The main characteristics of the HIV-1 patients were as follows: median age 8.1 years; 20/36 were males; 35 were vertical transmission cases; 34 were AIDS cases under antiretroviral therapy; median viral load = 3.04 log10 copies/ml; median CD4+ T cell count = 701 cells/μl. A total of 25 percent (9/36) and 87.5 percent (49/56) of HIV-1-infected and healthy participants, respectively, displayed DTH reactivity to at least one antigen (p<0.001). Among HIV-1-infected participants, reactivity to candidin predominated (8/36, 22.2 percent), while PPD positivity prevailed among healthy participants (40/56, 71.4 percent). PPD reactivity in the HIV-1-positive group was 8.3 percent (p<0.01). The median PPD induration was 2.5mm (range: 2-5mm) in the HIV-1 group and 6.0 mm among healthy participants (range: 3-15mm). There was no correlation between PPD positivity and age. No correlation between CD4+ T cell counts and DTH reactivity was observed among HIV-1-infected patients. CONCLUSIONS: DTH skin test responses, including PPD reactivity, were significantly lower among HIV-1-infected participants compared to healthy controls, which likely reflects advanced disease and T cell depletion.

INTRODUÇÃO: A contagem de células CD4+ representa marcador da resposta imune celular em pacientes infectados pelo HIV-1. Testes cutâneos de hipersensibilidade tardia (DTH) podem ser empregados para avaliar in vivo respostas celulares a antígenos comuns. MÉTODOS: DTH para derivado proteico purificado de tuberculina (PPD), esporotriquina, tricofitina, candidina e estreptoquinase/estreptodornase foram realizados. Foram testados crianças/adolescentes infectados pelo HIV-1 (n=36) e indivíduos saudáveis (n=56), soronegativos para HIV-1/HIV-2 pareados por sexo-idade, todos com cicatriz vacinal por BCG. Teste exato de Fisher foi aplicado (p<0,05). RESULTADOS: Entre as crianças/adolescentes infectados pelo HIV-1, mediana de idade=8,1 anos; 20/36 eram do sexo masculino; 35 casos de transmissão vertical; 34 casos de AIDS sob terapia antirretroviral; mediana de carga viral = 3.04lc10 cópias/ml; mediana de contagem de células CD4+ = 701 células/μl. Entre os infectados e saudáveis a reatividade DTH a pelo menos um dos antígenos foi, respectivamente, 25 por cento (9/36) e 87,5 por cento (49/56) (p<0,001). Reatividade à candidina predominou nos infectados (8/36, 22 por cento) e ao PPD nos indivíduos saudáveis (40/56, 71,4 por cento). A reatividade ao PPD entre infectados foi de 8,3 por cento (p<0,01). A mediana da induração ao PPD foi 2,5mm (variação: 2-5mm) entre infectados e 6,0mm (variação: 3-15mm) entre os saudáveis. Não observamos correlação entre positividade ao PPD e idade. No grupo de infectados, não observamos correlação entre contagens de células CD4+ e reatividade ao DTH. CONCLUSÕES: Respostas DTH significativamente diminuídas, incluindo a reatividade ao PPD foram observadas em crianças/adolescentes infectados pelo HIV-1 comparadas com controles saudáveis, provavelmente refletindo doença avançada e supressão da imunidade mediada por células T.

An experimental protocol for the establishment of dogs with long-term cellular immune reactions to Leishmania antigens

Domestic dogs are considered to be the main reservoirs of zoonotic visceral leishmaniasis. In this work, we evaluated a protocol to induce Leishmania infantum/Leishmania chagasi-specific cellular and humoral immune responses in dogs, which consisted of two injections of Leishmania promastigote lysate followed by a subcutaneous inoculation of viable promastigotes. The primary objective was to establish a canine experimental model to provide positive controls for testing immune responses to Leishmania in laboratory conditions. After inoculation of viable promastigotes, specific proliferative responses of peripheral blood mononuclear cells (PBMCs) to either Leishmania lysate or recombinant proteins, the in vitro production of interferon-γ by antigen-stimulated PBMCs and a significant increase in circulating levels of anti-Leishmania antibodies were observed. The immunized dogs also displayed positive delayed-type hypersensitivity reactions to Leishmania crude antigens and to purified recombinant proteins. An important finding that supports the suitability of the dogs as positive controls is that they remained healthy for the entire observation period, i.e., more than seven years after infection. Following the Leishmania antigen lysate injections, the infection of dogs by the subcutaneous route appears to induce a sustained cellular immune response, leading to an asymptomatic infection. This provides a useful model for both the selection of immunogenic Leishmania antigens and for immunobiological studies on their possible immunoprotective activities.

Hormônio de crescimento e hipersensibilidade por imunocomplexo (Tipo III): uma contraindicação para a dessensibilização / Growth hormone therapy and hypersensitivity type III reaction: a contraindication for desensitization

As reações alérgicas ao GH são raras e usualmente representadas por reações de hipersensibilidade tipo I (IgE mediadas), passíveis de tratamento por dessensibilização. Neste relato de caso, descrevemos a presença de reação alérgica ao GH mediada por imunocomplexo (hipersensibilidade tipo III). Nesta situação, a tentativa de dessensibilização pode perpetuar a formação de imunocomplexo, cujo depósito pode determinar insuficiência renal e respiratória.

Allergic reactions against GH are rare, and usually represented by the hypersensitivity type I (IgE-mediated). This type of reaction can be treated by desensitization. In this case report, we present a patient showing an allergic reaction soon after starting GH therapy mediated by immune complex (hypersensitivity type III reaction). In this condition, the attempt to perform the desensitization procedure can perpetuate immune complex deposition determining a life threatening renal and respiratory insufficiency.

Boosting the suppressive effects of Ascaris suum components in IFN-γ-deficient mice / Potencialização do efeito supressor de componentes do Ascaris suum em camundongos deficientes em IFN-γ

High molecular weight components from Ascaris suum extract suppress ovalbumin-specific immunity in mice. In IFN-γ-deficient mice, ovalbumin-specific delayed-type hypersensitivity reactions are more strongly downregulated by these suppressive components. Here, the cellularity of the delayed-type hypersensitivity reaction in IFN-γ-deficient mice and the increased downregulation induced by Ascaris suum components were analyzed. IL-12p40-dependent neutrophilic influx was predominant. Suboptimal doses of the suppressive fraction from this nematode completely inhibited the hypersensitivity reaction, thus indicating intensification of the immunosuppression under conditions of intense recruitment of IFN-γ-independent neutrophils.

Componentes de alto peso molecular do extrato de Ascaris suum suprimem a imunidade específica à ovalbumina em camundongos. Em camundongos geneticamente deficientes de IFN-γ a reação de hipersensibilidade tardia específica para ovalbumina foi mais fortemente prejudicada por estes componentes supressivos. Aqui, a celularidade da reação de hipersensibilidade tardia em camundongos deficientes de IFN-γ e o incremento na supressão induzida por componentes do Ascaris suum foram analisados. Influxo neutrofílico, dependente de IL-12p40, foi predominante. Dose sub-ótima da fração supressiva do nematódeo inibiu completamente a reação de hipersensibilidade, indicando uma intensificação da imunossupressão em condições de recrutamento intenso de neutrófilos independente de IFN-γ.

Melatonin treatment prevents modulation of cell-mediated immune response induced by propoxur in rats.

The effect of melatonin, a major secretory product of the pineal gland, in attenuation of propoxur (2-isopropoxy phenyl N-methyl carbamate)-induced modulation of cell-mediated immune (CMI) response was studied in rats. Male Wistar albino rats were exposed to propoxur (a widely used pesticide) orally (10 mg/kg) and/or melatonin (10 mg/kg) orally for 4 weeks. CMI was measured by delayed-type hypersensitivity (DTH), leucocyte and macrophage migration inhibition (LMI and MMI) responses and estimation of cytokines TNF-alpha and IFN-gamma levels. Rats exposed to propoxur for 4 weeks showed significant decrease in DTH, LMI and MMI responses. Propoxur also suppressed TNF-alpha and IFN-gamma production significantly. Administration of melatonin alone caused a significant increase in DTH response. Although there were no changes in the LMI and MMI response, the cytokine levels were significantly increased, as compared to control. Co-administration of melatonin along with propoxur significantly nullified the effect of the pesticide on the CMI response, except DTH and reversed levels of cytokines to near control/normal values. Thus, melatonin treatment considerably attenuated immunomodulation caused by sub-chronic treatment of propoxur in experimental animals.

Experimental infections with Paracoccidioides brasiliensis obtained from armadillos: comparison to clinical isolates

Paracoccidioides brasiliensis causes paracoccidioidomycosis (PCM) that is one of the most prevalent systemic human mycoses in Latin America. Armadillos show a high incidence of PCM infection and could, therefore, be a natural reservoir for this fungus. In this study were compared the virulence profiles of isolates obtained from nine-banded armadillos (Dasypus novemcinctus) (PbT1 and PbT4) and isolates from PCM patients (Pb265 and Bt83). Pathogenicity was evaluated by fungal load and analysis of colony morphology. Immunity against the fungus was tested by delayed type hypersensitivity test (DTH) and antibody quantification by ELISA. The higher virulence of PbT1 and PbT4 was suggested by higher fungal load in spleen and lungs. Armadillo isolates and Bt83 presented a cotton-like surface contrasting with the cerebriform appearance of Pb265. All isolates induced cellular and humoral immune responses in infected BALB/c mice. DTH reactions were similarly induced by the four isolates, however, a great variability was observed in specific antibody levels, being the highest ones induced by Bt83 and PbT4. The present work confirms that armadillos harbor P. brasiliensis, whose multiplication and induced immunity in experimentally infected mice are heterogeneous, resembling the behavior of isolates from human PCM. This study reinforces the possibility that armadillos play an important role in the biological cycle of this pathogen.

Infecção por L. (L. ) chagasi e associação entre anticorpos anti-saliva da Lutzomyia longipalpis e o teste cutâneo anti-leishmania em crianças resintes em áreas endêmicas der leishmaniose visceral, na ilha de São Luís, Maranhão / Infection L. (L. ) chagasi and association between anti-saliva of Lutzomyia longipalpis and the skin test to Leishmania in children in endemic areas Resinto der visceral leishmaniasis on the island of São Luis, Maranhão

A resposta humoral anti-saliva do flebotomíneo está associada à presença de anticorpos anti-Leishmania, em crianças residentes em áreas endêmicas para leishmaniose visceral (LV). Tais achados, entretanto, baseiam-se em um estudo seccional com uma pequena amostra. O presente estudo, de coorte prospectivo (janeiro 2003 a janeiro 2005) com 1080 crianças (idade inferior a 10 anos), objetiva avaliar o desenvolvimento de anticorpos anti-saliva do flebotomíneo, bem como, anticorpos anti-Leishmania e reação de hipersensibilidade tipo tardia (DTH) ao antígeno de Leishmania, e identificar possíveis fatores de risco para a infecção. As características demográficas da população estudada eram: 1 a 6 anos de idade (66,6 por cento), sexo feminino (52,0 por cento), cor parda (77,1 por cento) e residência em casa com cinco a sete pessoas (57,8 por cento). A cobertura de telha foi mencionada em 77,0 por cento dos domicílios e desses, 96,1 por cento eram servidas por rede de água tratada, 68,5 por cento queimavam o lixo produzido e em 51,2 por cento o destino dos dejetos era a fossa negra. A criação de animais foi referida por 52,3 por cento das famílias, e a proximidade destes (principalmente cães) por 93,7 por cento. Chiqueiro (20,6 por cento) e galinheiro (61.3 por cento) foram, frequentemente, relatados na proximidade das casas. A presença de flebotomíneos foi mencionada por 30,6 por cento dos familiares. História anterior de LV na família foi referida por 205 (19,0 por cento) das crianças envolvidas no estudo. A DHT no inquérito inicial mostrou prevalência de 31,8 por cento, com incidências de 24,6 por cento e 7,2 por cento, nos 12° e 24° meses de observação, respectivamente. A positividade ao teste ELlSA anti-leishmania a prevalência foi de 17,1 por cento (inquérito inicial) com incidências de 6,6 por cento, 3,8 por cento, 17,2 por cento e 37,3 por cento aos 6°, 12°, 18° e 24° meses, respectivamente. Apesar da positividade de anticorpos anti-leishmania, nenhuma criança desenvolveu sintomas de LV. A variável criação de animais esteve associada ao risco de infecção por L. (L.) chagasi, quando o exame utilizado foi o ELlSA, enquanto que, as variáveis abastecimento com água de poço, criação de animais e resposta negativa quanto a presença de flebotomíneo mostraram-se associadas quando o teste utilizado foi a DTH. Os anticorpos anti-saliva do flebotomíneo apresentaram prevalência de 16,1 por cento no inquérito inicial e incidências no 6°, 12°, 18° e 24° meses de, respectivamente, 0,4 por cento, 3,8 por cento, 1,9 por cento e 2,7 por cento. Não houve diferença estatisticamente significante nos níveis de anticorpos IgG anti-saliva nas diferentes faixas etárias (menores de 1 ano, de um a três, de quatro a seis, e de sete a nove anos de idade) no inquérito inicial (teste de Kruskal-Wallis usado para comparar os níveis de anticorpos nos diferentes grupos de idade e pontos de estudo). Com exceção do grupo de menores de 1 ano, os anticorpos IgG anti-saliva, declinaram em função do tempo (p<0.01 nos demais grupos de idade). A associação entre anticorpos anti-saliva e DTH anti-Leishmania foi estatisticamente significante (p< 0.0006 pela análise de sobrevivência de Kaplan-Meyer). Nossos resultados mostram que: a) altos títulos de anticorpos anti-leishmania nem sempre se correlacionam com o desenvolvimento de LV; b) a sensibilidade de anticorpos anti-saliva é baixa, uma vez que, muitas crianças foram expostas (evidenciado pelos anticorpos anti-leishmania ou DTH positivos), mas não exibiram reação anti-saliva positiva. Mais importante, este estudo de coorte forneceu evidências de associação estatisticamente significante entre anticorpos IgG anti-saliva do flebotomíneo positivos e resposta imuno-celular anti-leishmania.

Protective effect of lectin from Synadenium carinatum on Leishmania amazonensis infection in BALB/c mice

The protective effect of the Synadenium carinatum latex lectin (ScLL), and the possibility of using it as an adjuvant in murine model of vaccination against American cutaneous leishmaniasis, were evaluated. BALB/c mice were immunized with the lectin ScLL (10, 50, 100 microgram/animal) separately or in association with the soluble Leishmania amazonensis antigen (SLA). After a challenge infection with 10(6) promastigotes, the injury progression was monitored weekly by measuring the footpad swelling for 10 weeks. ScLL appeared to be capable of conferring partial protection to the animals, being most evident when ScLL was used in concentrations of 50 and 100 microgram/animal. Also the parasite load in the interior of macrophages showed significant reduction (61.7%) when compared to the control group. With regard to the cellular response, ScLL 50 and 100 microgram/animal stimulated the delayed-type hypersensitivity (DTH) reaction significantly (P < 0.05) higher than SLA or SLA plus ScLL 10 weeks after the challenge infection. The detection of high levels of IgG2a and the expression of mRNA cytokines, such as IFN-gamma, IL-12, and TNF-alpha (Th1 profiles), corroborated the protective role of this lectin against cutaneous leishmaniasis. This is the first report of the ScLL effect on leishmaniasis and shows a promising role for ScLL to be explored in other experimental models for treatment of leishmaniasis.

Time dependent immunomodulatory response of exogenous melatonin to killed Pasteurella multocida (P52 strain) vaccine in albino rats.

The effect of time of administration of exogenous melatonin (M) at the rate of 100 microg/Kg BW of rat/day for 14 days on immunomodulation to killed Pasteurella multocida (P52 strain) vaccine (KPMV) was investigated in male albino rats during spring season with photoperiod of LL 13: DD 11 h and 25 +/- 2.5 degrees C air temperature and 70 +/- 4% relative humidity. The experiment was conducted at an altitude of 172 mts above mean sea level at latitude 28.20 degrees north, longitude 79.24 degrees east (Bareilly, U.P. India). The experimental animals were divided in-groups of 8 rats each, as KPMV + M at 4.00 h; KPMV + M at 16.00 h; KPMV and their controls M4, M16, PBS respectively. Humoral immune response was monitored at weekly intervals by an indirect ELISA and cellular immunity by leukocyte migration inhibition test (LMIT) and delayed type of hypersensitivity (DTH). As evinced by in-vitro assays and in-vivo protection studies, both humoral and cellular immune responses to KPMV were augmented in rats receiving exogenous melatonin at 4.00 h as compared to slightly reduced responses in rats treated with melatonin at 16.00 h. It was concluded that the circadian timings of melatonin administration modulate immune response in rats.

Intradermorreação de Montenegro após sucessivas repetições do teste em Porteirinha, MG / Montenegro intradermoreaction after the test sequential repetitions in Porteirinha, Minas Gerais State, Brazil

Para avaliar a resposta a sucessivas aplicaçöes da intradermorreaçäo de Montenegro (IDRM), repetimos quatro vezes o teste em moradores de uma área endêmica de calazar que tiveram o exame negativo há 3-4 anos. Inicialmente, repetimos três IDRM nos que permaneceram negativos, com intervalo de 60 dias entre elas. Na segunda etapa, realizamos uma última reaçäo em todos participantes do estudo. Do total de 49 indivíduos com IDRM prévia negativa, 19 (38,8 por cento) positivaram o teste em alguma das vezes, 17 (34,7 por cento) abandonaram o estudo e 13 (26,5 por cento) permaneceram com resultado negativo em todas as aplicaçöes. Na segunda etapa, a repetiçäo da IDRM mostrou que dos 14 que eram positivos em algum dos testes, 8 assim permaneceram e 6 tornaram-se negativos. Nossos resultados confirmam a possibilidade de induçäo de hipersensibilidade tardia em alguns indivíduos pela aplicaçäo da IDRM

Leishmania (Leishmania) major-infected rhesus macaques (Macaca mulatta) develop varying levels of resistance against homologous re-infections

Seven rhesus macaques were infected intradermally with 10(7) promastigotes of Leishmania (Leishmania) major. All monkeys developed a localized, ulcerative, self-healing nodular skin lesion at the site of inoculation of the parasite. Non-specific chronic inflammation and/or tuberculoid-type granulomatous reaction were the main histopathological manifestations of the disease. Serum Leishmania-specific antibodies (IgG and IgG1) were detected by ELISA in all infected animals; immunoblot analyses indicated that numerous antigens were recognized. A very high degree of variability was observed in the parasite-specific cell-mediated immune responses [as detected by measuring delayed-type hypersensitivity (DTH) reaction, in vitro lymphocyte proliferation, and gamma interferon (IFN-gamma) production] for individuals over time post challenge. From all the recovered monkeys (which showed resolution of the lesions after 11 weeks of infection), 57.2 percent (4/7) and 28.6 percent (2/7) animals remained susceptible to secondary and tertiary infections, respectively, but the disease severity was altered (i.e. lesion size was smaller and healed faster than in the primary infection). The remaining monkeys exhibited complete resistance (i.e. no lesion) to each rechallenge. Despite the inability to consistently detect correlates of cell-mediated immunity to Leishmania or correlation between resistance to challenge and DTH, lymphocyte transformation or IFN-gamma production, partial or complete acquired resistance was conferred by experimental infection. This primate model should be useful for measuring vaccine effectiveness against the human disease

Inmunosenescencia: pruebas cutáneas de hipersensibilidad retardada en adultos mayores chilenos autovalentes / Immunosenescence: delayed cutaneous hypersensitivity test in free living chilean elderly individuals

Background: Delayed cutaneous hypersensitivity tests are a globally accepted test to assess cellular immunity in vivo. The quality and quantity of the response to these type of tests, varies in different populations. Aim: To study delayed cutaneous hypersensitivity in a group of healthy Chilean elders. Material and methods: Forty two elders (32 male), aged 60 to 76 years old were studied. Multitest-CMI(r) was applied in the left forearm. This test allows the subcutaneous administration of seven antigens and a glycerin control. Results were compared with those of a group of young adults studied by the authors. Results: Among males there was a mean of 2.7 ñ 1.4 positive responses compared with women, that had 1.7 ñ 1 positive responses (p= 0.016). The sum of response diameters was 4.2 ñ 1.5 and 3.6 ñ 1.9 mm in men and women respectively (p = NS). Compared to young adults, elderly women had a lower response to tetanus and diphtheria toxoids and men had a lower response to diphtheria and Proteus mirabilis. Conclusions: Elderly people have a less intense response to delayed cutaneous hypersensitivity tests than young adults. This response must be assessed in each population to account for regional variability

Immunological assessment in patients of leukaemia.

In the present study delayed cutaneous hypersensitivity response (DNCB test) and humoral response (by uantification of immunoglobulins) ware carried out in 20 cases of leukaemias. None of the cases was found to be anergic or immunodeficient. In remission also patients showed the normal response.

Cutaneous delayed-type hypersensitivity responsiveness in lepromatous and borderline lepromatous leprosy patients as determined by MULTITEST CMI.

To assess cell mediated immune (CMI) function in patients with lepromatous and borderline lepromatous leprosy (LL and BL), 35 patients were examined with the MULTITEST CMI system to evaluate cutaneous delayed-type hypersensitivity (DTH) responsiveness to 7 recall antigens. Reactions were assessed quantitatively and qualitatively. In addition, patients were classified as "responsive" (> or = 2 positive reactions), "hypo-responsive" (1 positive reaction), or anergic. Only hyporesponsive and anergic patients were re-tested. In 23 patients tested before treatment started (Group 1), 9 were responsive, 4 hypo-responsive, and 10 anergic. Upon re-testing, 10 of the 14 hyporesponsive-anergic subjects showed improvement. In 12 patients assessed after therapy initiation (Group 2), 9 were responsive and 3 others became responsive upon re-testing. Quantitative assessment indicated variable deficiencies in cutaneous DTH reactivity that, in many cases, improved with therapy. Correlations between reactivity and disease severity (LL versus BL) or duration of disease were not observed. The MULTITEST CMI system provided a convenient, safe, and reproducible method to assess cutaneous DTH responsiveness in LL and BL patients. Our findings indicated that most LL and BL patients are able to generate detectable but generally fewer and less robust cutaneous DTH responses to recall antigens, many improving with therapy. However, a semi-quantitative classification whereby patients that reacted to 2 or more antigens were considered "responsive" showed little difference between patients and controls. Overall, the data support the contention that deficits in cutaneous DTH responsiveness probably neither predispose nor necessarily accompany lepromatous disease, a practical consideration as efforts to develop a leprosy vaccine continue.