Decreased memory T-cell response and function in human immunodeficiency virus-infected patients with tegumentary leishmaniasis

The effects of human immunodeficiency virus (HIV) on the immune response in patients with cutaneous leishmaniasis have not yet been fully delineated. This study quantified and evaluated the function of memory T-cell subsets in response to soluble Leishmania antigens (SLA) from patients coinfected with HIV and Leishmania with tegumentary leishmaniasis (TL). Eight TL/HIV coinfected subjects and 10 HIV seronegative subjects with TL were evaluated. The proliferative response of CD4+and CD8+T-cells and naïve, central memory (CM) and effector memory (EM) CD4+T-cells in response to SLA were quantified using flow cytometry. The median cell division indices for CD4+and CD8+T-cells of coinfected patients in response to SLA were significantly lower than those in patients with Leishmania monoinfection (p < 0.05). The proportions of CM and EM CD4+T-cells in response to SLA were similar between the coinfected patients and patients with Leishmania monoinfection. However, the median CM and EM CD4+T-cell counts from coinfected patients were significantly lower (p < 0.05). The reduction in the lymphoproliferative response to Leishmania antigens coincides with the decrease in the absolute numbers of both EM and CM CD4+T-cells in response to Leishmania antigens in patients coinfected with HIV/Leishmania.

Brain tumor inhibition in experimental model by restorative immunotherapy with a corpuscular antigen.

In view of the advances in our understanding of anti-tumor immune response, it is now tempting to contemplate the development of immunotherapies for malignant brain tumors, for which no effective treatment exists. Immunotherapy, with agents known as biological response modifiers (BRMs) are thus gaining increasing interest as the fourth modality of treatment. A non-specific BRM, sheep erythrocytes (SRBC) when administered (ip, 7% PCV/V, 0.5 ml) in a group of animals at the end of seventh month of ethylnitrosourea administration, resulted in significant increase in the mean survival time (> 350 days). Studies conducted for growth kinetics pattern with proliferation index and fluorochrome (HO-33342) uptake techniques at the tissue culture level exhibited a regulatory inhibition of the cells isolated from tissue excised from the tumor susceptible area of brain of SRBC treated animals. Moreover, histological examination of brain from animals showed immunomodulatory role of SRBC in experimentally induced brain tumor. Further probe into the mechanisms involving immunological investigations at the cellular level in these animals indicated an augmented and potentiated cell mediated immune response (CMI) as evidenced by enhanced spontaneous rosette forming capacity and cytotoxic activity of lymphocytes and neutrophil (PMN) mediated phagocytosis respectively. The observations suggest that SRBC down regulate malignant growth pattern of experimental brain tumors either by an immunologically enhanced killing of tumor cells and/or by directly inhibiting the tumor growth possibly via a stimulated cytokine network. Thus, a corpuscular antigen, can potentiate CMI response in experimentally induced brain tumor animal model, in which response induced in the periphery are able to mediate anti-tumor effects in the brain.

Células mononucleares de sangue de cordão umbilical e de sangue periférico estimulado com fator de crescimento granulocítico (G-CSF): análise da proliferação e de apoptose in vitro / Mononuclear cells of umbilical cord blood and of granulocyte colony-stimulating factor: analyses of proliferation and apoptosis in vitro

Células mononucleares de sangue de cordão umbilical (SCU) e sangue periférico mobilizado (SPM) com G-CSF, foram cultivadas in vitro com citocinas, na presença ou não de estroma de medula óssea. Os objetivos foram avaliar a capacidade proliferativa de células progenitoras, a ocorrência de apoptose e expressão de integrina. Nas culturas sem estroma, a celularidade aumentou 5 vezes (SCU) e não se alterou nas de SPM. O total de células CD34+ caiu em ambas culturas. Com estroma, o total de células nucleadas aumentou 7 vezes (SCU) e 2,3 vezes (SPM). O total de células CD34+ permaneceu o mesmo. A apoptose foi menor nas culturas de SCU. A expressão de integrina caiu, na população de células CD34+ e de CD45+ / Mononuclear cells from umbilical cord blood (UCB) and G-CSF mobilized peripheral blood (MPB), were cultured in vitro, in the presence of cytokines, with or without bone marrow stroma. The aims were to evaluate the proliferative response of progenitor cells, occurrence of apoptosis and expression of adhesion molecule. In cultures without stroma, cellularity increased 5-fold for UCB, but has not changed for MPB. The number of CD34+ cells has dropped in both culture. With stroma, total nucleated cells had a 7-fold increse (UCB) and a 2,3-fold (MBP), however, CD34+ cells number has not changed. Apoptosis was lower in UCB culture. The expression of integrin decreased, in the...

Active Immunization Using Dendritic Cells Mixed With Tumor Cells Inhibits The Growth Of Lymphomas

Dendritic cells (DCs) are potent antigen-presenting cells for the induction and activation of cytotoxic T lymphocytes. We tested whether bone marrow derived DCs are capable of inducing protective immunity against a murine lymphoma (A20). DCs were grown from tumor-bearing BALB/c mice by culturing bone marrow cells. BALB/c mice were injected (sc) with A20 cells on day 0. Intraperitoneal immunization with DCs mixed with lethally irradiated A20 cells were started when the tumor reached ca. 4-5 mm in diameter (Group A) or on day -7 (Group B). Booster immunizations were given every 3-4 days for four weeks. By 31 days in group A, there was a significant reduction in tumor growth in the mice immunized with DCs mixed with irradiated A20 cells as compared with the control groups (p=0.016). In group B, tumor growth was completely inhibited and there was no tumor growth following extended observations after completion of immunization. Thus, DCs mixed with irradiated tumor cells can induce an antitumor effect. This provides a rationale for the use of DCs mixed with irradiated tumor cells in immunotherapy for minimal residual disease of lymphomas.

Evaluation of immune responses directed against 30kDa secretory protein of Mycobacterium tuberculosis H37Ra complexed in different adjuvants.

Ability of different adjuvants to promote cell mediated immune responses towards 30 kDa secretory protein of Mycobacterium tuberculosis H37Ra was monitored by assessing the lymphocyte proliferation and IgG1/IgG2a subclass profile in mouse model. Six formulations, viz. poly lactide-co-glycolide (PLG) microspheres, dimethyldioctadecyl ammoniumbromide (DDA), liposomes, liposomes containing monophosphoryl lipid A and coated with alum (L-LIPA-AL) or without alum (L-LIPA) were evaluated in comparison to standard Freund's incomplete adjuvant (FIA). Two adjuvant formulations of 30kDa-L-LIPA-AL and 30kDa-PLG showed maximum reactivity on VIIIth week post immunization (p.im) in terms of lymphoproliferation w.r.t. other adjuvant formulations. Both the vaccine formulations also exhibited a Th1 shift in terms of higher IgG2a response over IgGI. Flowcytometric analysis in the mesenteric lymph nodes (MLNs) of immunized animals revealed the capacity of 30kDa-PLG and 30kDa-L-LIPA-AL to activate T cell subsets like CD4 and CD8 T cells. The upregulation of B7 costimulatory molecules (B7-1 & B7-2) after immunization further proved the ability of the two vaccine formulations to activate antigen presenting cells. The immunostimulatory nature of the two formulations was also reflected in their capacity to reduce the bacilli load from the lungs of the experimentally infected mice. This study demonstrates PLG and L-LIPA-AL as potent adjuvants and their bioacceptibility and nontoxic nature make them suitable candidates for future subunit vaccine development against tuberculosis.

Dengue virus specific T cell responses to live attenuated monovalent dengue-2 and tetravalent dengue vaccines.

The proliferative T cell responses to dengue vaccines were studied using the parental strains of dengue vaccines as antigens in 26 dengue immune individuals who resided in Bangkok which is the endemic area of dengue infection. The magnitude of the T cell responses in subjects with flavivirus cross-reactive neutralizing antibody was much higher and the cross-reactivity was broader than in those with dengue serotype-specific neutralizing antibodies, Japanese encephalitis (JE) specific antibodies or dengue cross-reactive antibodies. The T cell response in those with neutralizing antibody against a single serotype or in those who had dengue cross-reactive neutralizing antibody was relatively low, independent of the level or degree of cross-reactivity of the antibody. Evaluation of the proliferative T cell responses in 8 recipients of the monovalent dengue-2 (16681-PDK53) or the tetravalent dengue vaccines demonstrated that both vaccines induced high levels of neutralizing antibody as well as high levels of T cell responses to all serotypes of dengue virus. These results indicate that the evaluated dengue vaccines efficiently induced humoral and cell mediated immunity comparable to natural infection with dengue virus.

Lack of in vitro lymphoproliferative response to hepatitis B surface antigen in healthy vaccine recipients.

A majority of HBsAg vaccine recipients show good anti-HBs antibody responses but poor antigen specific lymphoproliferative responses. We investigated the basis for this poor in vitro antigen specific proliferative responsiveness in vaccinees who had received the standard three dose schedule (0, 1 and 6 months) of plasma derived HBsAg vaccine. Peripheral blood mononuclear cells (PBMC) from 26 of 29 (89.7%) vaccinees failed to show lymphoproliferative responses to HBsAg in spite of having a very good anti-HBs antibody response (geometric mean titre 3154 IU/1). The mitogen (phytohaemagglutinin, PHA) and antigen (purified protein derivative, PPD) driven lymphoproliferative responses in these individuals were normal. Addition of exogenous recombinant interleukin-2 (rIL-2) along with HBsAg had no effect in the response to HBsAg in six of nine vaccinees, who were tested six months after the third vaccine dose or in four unvaccinated controls. However, in three vaccinees who did not have lymphoproliferative response to HBsAg alone, addition of exogenous rIL-2 resulted in a synergistic response. These data suggest that HBsAg reactive cells are few in the peripheral circulation of a majority of individuals following the standard three dose schedule of vaccination and addition of exogenous rIL-2 induces a response only in a subgroup of individuals. The inability of HBsAg to induce a T cell proliferative response may have implications for the maintenance of protective immunity and immunological memory following vaccination.

Inhibitory serum factor of lymphoproliferative response to allogeneic cells in pregnancy

An inhibitory serum factor of mixed lymphocyte culture (MLC) has been associated with successful pregnancy after lymphocyte transfusion in women with unexplained recurrent spontaneous abortions (RSA). Objective: Investigate whether the inhibitory serum factor of MLC is essential for a successful pregnancy. Method: Sera from 33 healthy pregnant women and from 40 women with RSA were assessed by a one-way MLC in which the woman's lymphocytes were stimulated with her partner's lymphocytes or with third party lymphocytes. Results: An inhibitory serum effect (inhibition >50 percent as compared to normal serum) was detected in 45 percent of the pregnant women who had at least 1 previous parity, in 8 percent of the primigravidea, in 29 percent of those with one abortion and in 58 percent of those with more than one abortion. Conclusion: MLC inhibitory serum factor does not seem to be an essential factor for pregnancy development. Therefore, it should not be considered as a parameter for the assessment of RSA patients.

Human immune response to triatomine embryo extract

Dipetalogaster maximus embryo extracts were used to stimulate peripheral blood mononuclear cells (PBMC) and in ELISA with sera either from Trypanosoma cruzi infected or non-infected individuals. The results showed that there was significant proliferative response and high antibody, titers in sera of chagasic patients.

A conserved epitope on nuclear pore phosphoproteins reflects cell division status.

The nuclear pore complexes mediate the selective nuclear import of proteins in a signal- and energy-dependent process. We have earlier reported the characterization of a monoclonal antibody, Mab E2, that recognizes a novel class of nuclear pore phosphoproteins involved in signal-binding and protein transport. In the present study, we have analyzed the pattern of immunoreactivity of Mab E2 in cultured rat fibroblasts and have observed significant differences in the expression of epitopes in proliferating and quiescent cells. Furthermore, the common epitope recognized by Mab E2 is conserved across species, consistent with its essential role in nuclear protein import.

Depressed specific and nonspecific immune responses in secondary Brugia pahangi infection in jirds.

The immune responsiveness to specific antigens or mitogens was examined in jirds after primary and secondary infections with Brugia pahangi. When spleen cells were obtained from secondarily infected jirds, their proliferative responses to mitogens such as Con A or LPS, or to specific antigens prepared from infective larvae or adult worms were significantly lower than those of spleen cells obtained from primarily infected jirds. The proliferative responses of the peripheral blood mononuclear cells obtained from animals undergoing primary and secondary infections also showed a similar tendency. The depressed proliferative responses of the secondary infected spleen cells to Con A or LPS was partially restored by removing adherent/phagocytic cells from the original cell populations. After deletion of the adherent cells, however, antigen-specific proliferative responses were not altered and remained at low level. These results suggest that at least two different mechanisms of depression, namely adherent cell-mediated antigen-nonspecific suppression and unresponsiveness of lymphocytes to filarial antigens, are induced in jirds in the secondary infection.

Marcadores da proliferaçåo celular / Proliferative-cell markers

A capacidade proliferativa aumentada é uma das principais características das células tumorais. A detecçåo e a quantificaçåo das células em proliferaçåo constituem-se parâmetros importantes no prognóstico de diferentes tumores, uma vez que a capacidade proliferativa tem sido considerada marcadora de alguns tumores e até mesmo associada ao grau de malignidade de outros. Frente aos recentes avanços no conhecimento dos mecanismos envolvidos na divisåo celular e dos diferentes fatores controladores das diversas fases do ciclo celular, novos métodos tém sido desenvolvidos para detectar e quantificar as taxas de crescimento tecidual e/ou neoplástico. Neste trabalho såo revisados diferentes métodos de quantificaçåo celular, procurando-se salientar a importância do desenvolvimento de anticorpos monoclonais contra proteínas marcadoras do ciclo celular e seu emprego na detecçåo imunocitoquímica de células em proliferaçåo