Monitoring of visual field over 6 months after active ocular toxoplasmosis.

PURPOSE: To prospectively report the perimetric defects during a 6-month follow-up (FU) in patients with initially active ocular toxoplasmosis (OT). METHODS: Twenty-four patients were studied, including 11 eyes with chorioretinal toxoplasmosis proven with a positive aqueous humor sample and 13 eyes with a biologically unproven, chorioretinal lesion. Automated 24-2 SITA-Standard visual fields were performed at baseline, at the first, and sixth months of FU. A composite clinical severity score was calculated from visual acuity (VA), severity of vitreitis, chorioretinal lesion size, location of the lesion in zone 1, the presence of an initial macular or papillary edema, and long-term scarring. This provided a relative cutoff level of severity. Nine eyes out of the 24 eyes were considered severe (3 unproven and 6 proven OT). RESULTS: Initial and final visual field parameters (mean deviation [MD] and pattern standard deviation [PSD]) were significantly correlated (r = 0.873; p < 0.001, and r = 0.890; p < 0.001, respectively). During FU, only foveal threshold [FT] was correlated with VA at baseline (r = 0.48; p = 0.01) and at the 6-month FU visit (r = 0.547; p = 0.004). The MD initial predictive value of clinical severity was 0.739 according to the ROC curve. At baseline, severe and nonsevere OT exhibited no significant difference in term of MD (p = 0.06) and PSD (p = 0.1). During the FU, taking into account all the data, MD, PSD, visual function index [VFI], and FT were associated with the severity of toxoplasmosis (p = 0.018, 0.05, 0.016, and 0.02, respectively): the unproven group had a faster recovery of MD during FU (p = 0.05). CONCLUSION: Visual field parameters better reflected the chorioretinal destruction related to the toxoplasmosis lesion and the functional repercussions than VA alone. Interestingly, MD at presentation could be a discriminating factor of severity in active OT, and each visual field parameter follow-up could be a support to manage patients with active OT, especially in the severe group.

Biological autoimmunity screening in hepatitis C patients by anti-HepG2 lysate and anti-heat shock protein 70.1 autoantibodies.

Viruses require viral and cellular chaperones during their life cycle and interactions of these molecules with the immune system are probable during the infection. Thus, an anti-chaperone antibody response has been firstly investigated in hepatitis C patients in this paper. A HepG2-lysate antigen (90, 79, 72, 70, 62, 54 and 48 kDa) was assayed in sera from 59 (19F/40M) chronic hepatitis C patients without cirrhosis before therapy. Forty of them were positive for anti-HepG2 lysate antigen antibodies and this test may evaluate biological autoimmunity. Hsp70.1, Hsp90 and calreticulin levels were significantly higher in this antigen than in a control HepG2 antigen. Secondly, Hsp70.1 was identified as Hsp 70 kDa protein-1 by proteomic analysis and studied as a possible antibody target. Fourteen out of 59 patients were positive for anti-Hsp70.1 antibodies that were inversely correlated with alanine aminotransferase levels, the Metavir activity index and viraemia. Finally, for comparative purposes, 50 sera from systemic lupus erythematosus (SLE) patients have been tested: eight and 41 of them were positive for anti-Hsp70.1 and anti-HepG2 lysate antigen antibodies, respectively. Therefore, anti-Hsp70.1 autoantibodies may be produced and can partially lead to biological autoimmunity in chronic hepatitis C patients.

Aspergillus Fumigatus antigen detection in sera from patients at risk for invasive aspergillosis.

We have developed an inhibition enzyme immunoassay (inhibition-EIA) to monitor for the occurrence of invasive aspergillosis (IA) in sera from 45 immunocompromised (IC) patients. The test uses rabbit polyclonal antibodies and a mixture of components from Aspergillus fumigatus, containing three predominant antigens with molecular weights of 18,000, 33,000, and 56,000. Circulating antigens were found in five of seven proven cases of IA due to A. fumigatus. In two of the five positive cases, antigenemia was detected with inhibition-EIA earlier than with X ray or other biological methods. No antigens were detected in the sera from two patients with proven IA due to Aspergillus flavus and Aspergillus terreus nor in the sera from four patients with probable IA. Circulating antigens were not detected in the control group, composed of 30 healthy adult blood donors. Four of the 32 at-risk patients examined, though they displayed no definite evidence of IA, gave a positive result in this test. The sensitivity, specificity, and positive predictive value of inhibition-EIA were 71.4, 94.4, and 71.2%, respectively. The data were compared with those obtained by a latex agglutination assay of galactomannan (GM) that was positive in only one patient with probable IA. The higher sensitivity obtained by inhibition-EIA may well be due to its ability to detect circulating antigens other than GM in the sera of IC patients with IA. Detecting these antigens may improve the diagnosis of IA, as they may serve as markers of this infection.

Human platelet inhibition of Toxoplasma gondii growth.

The human platelet contribution against the intracellular growth of the parasite in vitro in human pulmonary fibroblasts was explored. It was observed that tachyzoites of Toxoplasma gondii induced activation of human platelets and additionally that platelets mediated inhibition of intracellular growth in a virulent T. gondii strain. A prominent role for platelet-derived growth factor (PDGF) was demonstrated in this phenomenon, by testing human recombinant PDGF-AA, -AB and -BB and antibodies to human PDGF-AB that partially reversed its effects. Moreover, the effect of PDGF was significantly higher if the host cells were treated 2 h before parasite infection. PDGF was not directly 'toxic' to free tachyzoites, but only affected parasites within host cells. PDGF-mediated inhibition may involve the cyclooxygenase cycle of the fibroblasts being partially reversed by the cyclooxygenase inhibitors, acetylsalicylic acid and indomethacin. However, a thromboxane synthetase pathway was not implicated. PDGF action against intracellular tachyzoites may also include increased IL-6 production in fibroblasts. Finally, transforming growth factor-beta 1 (TGF-beta1), another component of alpha-granules released at the same time as PDGF, may not be antagonistic to the PDGF parasite inhibitory effect in confluent host cells.

Apoptosis related to chloroquine sensitivity of the human malaria parasite Plasmodium falciparum.

As chemoresistance of Plasmodium falciparum to chloroquine has arisen, new ways of combating the infection are needed. Similarities exist between the multidrug resistance of mammalian cells and chloroquine resistance of P. falciparum, based on the occurrence of internucleosomal deoxyribonucleic acid (DNA) breakdown and the ability of some anticancer drugs and chloroquine to induce apoptosis. Using chloroquine, oligonucleosomal DNA fragmentation was observed with a sensitive strain of P. falciparum, but not with a resistant one. This suggests that apoptosis may be involved in the action of chloroquine on the parasite.

IgG1 and IgG2 antibody responses to Plasmodium falciparum exoantigens correlate inversely and positively, respectively, to the number of malaria attacks.

In Manarintsoa, near Antananarivo, Madagascar, two groups of patients were defined in terms of malaria clinical immune status: Group MA+ consisted of 36 patients who suffered from between one to four malaria attacks (MA) during the 20-week study, and Group MA- who comprised of 48 persons who did not have any malaria attacks during this time. In group MA+, IgM and IgG antibody levels to Plasmodium falciparum exoantigens (E-Ag) were inversely related to the number of malaria attacks. The level of IgM antibodies were significantly higher in group MA+. In contrast, IgG, IgG1, IgG2, IgG3 and IgG4 antibodies to E-Ag were significantly higher in group MA-. The level of IgG1 antibodies was inversely correlated, and IgG2 antibodies were positively correlated to the number of malaria attacks.

Toxoplasma gondii surface antigen-1 in sera of HIV-infected patients as an indicator of reactivated toxoplasmosis.

The major surface antigen from the proliferative form of Toxoplasma gondii (P-30 of SAG-1) was chosen as a target for exploration of Toxoplasma gondii reactivation in sera from immunocompromised patients. Samples were obtained from 37 HIV-infected subjects with lymphocyte levels of CD4+ < 200/mm3. The prevalence of IgG antibodies to Toxoplasma gondii was 64.9%. Ten patients had clinical symptoms of reactivated toxoplasmosis; eight of these had Toxoplasma encephalitis. The SAG-1 epitopes were found as circulating antigen in five cases with an immunocapture enzyme immunoassay (EIA). The EIA was improved with an IgG1 monoclonal antibody to SAG-1 and a streptavidinbiotin amplification. The sensitivity, specificity and positive predictive value were 30, 92 and 60%, respectively. The SAG-1 levels were compared with different biological parameters such as HIV p24 antigen, beta 2 microglobulin, CD4+ cell count and IgG antibodies to Toxoplasma gondii. The levels of SAG-1 in these patients were significantly higher than those in the 75 healthy control persons with or without a chronic Toxoplasma gondii infection. Therefore, SAG-1 may be involved as a marker of reactivated toxoplasmosis in HIV-infected patients.

Diagnosis of congenital toxoplasmosis by immunoblotting and relationship with other methods.

Immunoblot has been evaluated as a diagnostic method for congenital toxoplasmosis. Like enzyme-linked immunofiltration assay (ELIFA), immunoblot can be used to compare antibody patterns and to determine if the antibodies are transmitted by the mother or synthesized by the fetus or infant. Among the 48 infants tested, 27 had congenital toxoplasmosis and 21 were suspected but had none. Reproducibility, sensitivity, specificity, and positive predictive values in immunoblot for immunoglobulins (Igs) G+M+A and/or G+M were 90, 92.6, 89.1, and 92.4%, respectively. G+M immunoblot and G+M ELIFA have better sensitivities than the conventional IgM immunosorbent agglutination assay, IgM enzyme-linked immunosorbent assay (ELISA), IgM immunofluorescence antibody test, in vitro culture, and mouse inoculation. The novel antibodies, i.e., those synthesized by infants against Toxoplasma gondii, were of the IgG class in most cases, although a confident diagnosis could be related to the number of observed Ig classes (G+M, G+A, and G+M+A). Immunoblot has a better resolution than ELIFA. In prenatal diagnosis, immunoblot could be complementary to in vitro culture and mouse inoculation. In the other cases, early detection by immunoblot appears to give the best results when compared with the other serological methods.

Sera of patients with high titers of immunoglobulin G against Toxoplasma gondii induce secretion of tumor necrosis factor alpha by human monocytes.

Toxoplasma gondii alone does not induce tumor necrosis factor alpha (TNF-alpha) secretion by human monocytes and macrophages. Nevertheless, sera from infected patients with high titers of specific immunoglobulin G antibodies against T. gondii induce TNF-alpha secretion, which is significantly higher than the corresponding induction by negative sera (P less than 0.05). After incubation with the positive serum, parasites also induce secretion of this cytokine, but TNF-alpha levels are lower (11.4 to 71.8%) than those obtained with positive serum alone. Therefore, this secretion seems to be elicited in part by antibody-T. gondii complexes and/or another unidentified factor(s), probably different from lipopolysaccharide, interleukin-1, TNF-alpha, and gamma interferon. In this study, monocytes secreted more TNF-alpha into the culture fluid than macrophages did (P less than 0.05), and no correlation was observed between secretion of this cytokine by the monocytes and the intracellular multiplication of the parasites, evaluated by [3H]uracil incorporation. Sera from patients with other infections diseases did not induce secretion of TNF-alpha; however, serum free of antibodies to T. gondii, obtained from patients with leishmaniosis, also stimulated secretion of the cytokine.

Relationships between circulating S-antigens, naturally acquired antibodies to Plasmodium falciparum exoantigens and malaria attack in a mesoendemic area.

A survey involving 77 individuals living in two savannah villages near Bobo Dioulasso (Burkina Faso, West Africa), was performed in June 1987 (before), August-September (during) and January 1988 after the seasonal transmission. The clinical longitudinal study during the seasonal period permitted us to define three different groups in terms of both age and occurrence of malaria attack (MA; greater than or equal to 5000 parasites/mm3 of blood and axillary fever greater than or equal to 37.8 degrees C). The presence of circulating stable antigen (S-Ag) and the antibody responses against exoantigens (E-Ag) of Plasmodium falciparum were also evaluated at three observations periods: beginning, during and after the transmission season. The adult group (III) had the highest rates of IgG Ab to E-Ag although, IgM prevalence to E-Ag was maximal in the group II (individuals with no malaria attack and age less than or equal to 15 years old). Group I (persons with less than or equal to 15 years old and who contracted at least one MA) did not have any S-Ag at the first observation period and showed the lowest rate of antibodies to E-Ag. The probability of occurrence of an MA calculated from these parameters at the beginning of the transmission period were correct in 78.9% of the cases in children (Groups I & II) and in 71.8% of adults during the subsequent transmission period. Therefore these values could be used for evaluating the probability of occurrence of a clinical MA during the transmission period in a mesoendemic area. S-Ag and antibodies to E-Ag could participate positively in the mechanisms involved in the development of the immune status.

Brain-tissue cysts in rats infected with the RH strain of Toxoplasma gondii.

Virulent strains of the coccidian parasite Toxoplasma gondii become attenuated so as to survive and complete their life cycle; however, it is not known whether the attenuation process is attributable to an innate cystogenic capacity of the parasite or to host-induced mechanisms. This report presents direct evidence of RH cystogenesis in non-immunised Fischer rats and subsequent attenuation of RH pathogenicity in non-immunised mice following a single passage through rats. Taken together, these preliminary observations tend to suggest that at least one mechanism of T. gondii involves intermediate host attenuation.

Relationships between clinical protection and antibodies to Plasmodium falciparum RESA (ring-infected erythrocyte surface antigen) peptides.

A longitudinal study involving 76 individuals living in Dafinso and Vallée du Kou (near Bobo-Dioulasso, Burkina Faso, West Africa) was performed in June 1987 (beginning of the transmission period), August-September 1987 (during) and January 1988 (after). The serological antibody (Ab) responses against synthetic peptides representing repeat amino acid sequences of the P. falciparum Ring-Infected Erythrocyte Surface Antigen (RESA): (EENV)5, (EENVEHDA)4, (DDEHVEEPTVA)2 were evaluated by ELISA. The clinical longitudinal study during the transmission period allowed us to define three different groups in terms of age and occurrence of clinical malarial attack (greater than 5000 parasites mm-3 of blood and axillary fever greater than 37.7 degrees C). Levels (A620) of Ab to (EENVEHDA)4 and (DDEHVEEPTVA)2 were correlated with age. The adult group (III) had the highest prevalences of Ab to RESA peptides. No significant difference was found between groups of children with or without malaria attack. Nevertheless, at the beginning of the transmission period, children who had at least one malaria attack during the study presented the lowest level of antibodies to RESA peptides.

Correlation between beta 2-microglobulin and soluble interleukin-2 receptor levels in plasma of individuals living in a malarial endemic region.

beta 2-Microglobulin (beta 2m) levels were related to the expected immunoprotection in 81 individuals living in a malarial mesoendemic area near Bobo-Dioulasso (Burkina Faso), who were longitudinally followed. Soluble interleukin-2 receptor (sIL-2R) levels were positively correlated to those of beta 2m (r = 0.44; n = 237; P less than 0.001). This suggests that most of the beta 2m could have originated from activated T and B cell membrane turnover. In our study, both beta 2m and sIL-2R were inversely related to IgG antibodies (Ab) against somatic antigen of Plasmodium falciparum (Som-Ag). Therefore, these molecules at high levels could have a down regulating activity, directly or indirectly, on B cells producing this kind of Ab.

Longitudinal survey in an endemic region of plasma soluble interleukin-2 receptor and antibody levels in Plasmodium falciparum malaria.

A survey involving 81 individuals living in Dafinso and Vallée du Kou no. 4 (near Bobo-Dioulasso), Burkina Faso, was performed in June 1987, August to September 1987, and January 1988, respectively, at the beginning of, during, and after the transmission season of malaria. The clinical longitudinal study during the transmission period allowed us to define three different groups in terms of both age and occurrence of malaria attack (5,000 Plasmodium falciparum per mm3 of blood and axillary fever of greater than 37.7 degrees C) as follows: group 1, persons less than or equal to 15 years old who had at least one malaria attack during the transmission period; group 2, individuals less than or equal to 15 years old who did not have any malaria attacks; and group 3, individuals considered to be protected (adults greater than 15 years old with no malaria attacks). Soluble interleukin-2 receptor (sIL-2R) levels were found to be significantly increased (P less than 0.001) in the first two groups (1,047 +/- 481 U/ml [mean +/- standard deviation]) as compared with the adult group (605 +/- 307 U/ml). Considering all the groups, no significant difference was observed between observation periods. Levels of sIL-2R were inversely correlated (r = -0.39, n = 237, P less than 0.01) with age (range, 4 to 67 years). Negative correlations were also noticed between the levels of sIL-2R and those of antibodies to somatic antigen of P. falciparum (immunoglobulin G [IgG] class [r = -0.33, n = 237, P less than 0.01] and IgM class [r = -0.20, n = 237, P less than 0.05]). IgG antibody levels to somatic antigen were correlated with age, but IgM antibody levels to somatic antigen were not. The possible role played by sIL-2R in effector mechanisms against malaria is discussed.