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Bovine mononuclear cells in the presence of bovine anti-chicken erythrocyte sera at high dilutions induce release of chromium-51 from labeled chicken erythrocytes. Bovine effector cells are capable of recognizing both bovine immunoglobulin G(1) and bovine immunoglobulin G(2); in contrast, human effector cells only recognize immunoglobulin G(1). Effector cell activity of bovine mononuclear cells is equally distributed between peripheral blood and spleen. As in other species, thymus and lymph node cells exert no antibody-dependent effect, although some direct cytotoxicity by lymph node cells may be observed. Antibody-dependent cell-mediated cytotoxicity against a bovine cell line can also be detected. By using a tannic acid technique, it was found that chicken erythrocytes coated with Theileria parva piroplasm antigen or with Trypanosoma rhodesiense variant-specific coat antigen form suitable targets for bovine antibody-dependent cell-mediated cytotoxicity assays. By using such targets, a moderate degree of direct cytotoxicity by bovine mononuclear cells, in the absence of antibody, is always observed; this may be reduced by choosing optimal conditions of tannic acid treatment and antigen sensitization and by the use of short incubation periods for the cytotoxicity assay. Observations have been made on the variant specificity, time course of appearance, and association with immunoglobulin G(1) of the antibody activity responsible for cell-dependent cytotoxicity against chicken erythrocytes coated with T. rhodesiense antigens. The potential usefulness of this technique in the analysis of protective immune responses against protozoal infections is discussed.

We have constructed a small vector specifically for blunt-end cloning of fragments of DNA. Both the PvuII site and the EcoRI site allow the detection of recombinants using a simple and inexpensive colour screen. We have used this vector to construct cDNA clone banks from polyadenylated messenger RNA [poly(A)+mRNA] from several life cycle stages of the human parasite Schistosoma mansoni and have identified clones encoding an immunodiagnostic antigen gene by a combination of Southern blotting and mRNA hybrid-selection and in vitro translation. Antibodies against this antigen are only present in patients infected with S. mansoni.

Background. There is evidence from experimental models that the praziquantel-induced clearance of schistosomiasis is dependent on the host's immune response. Consequently, human immunodeficiency virus (HIV)-related immunodeficiency may impair the effect of praziquantel treatment. Methods. In a prospective cohort study, schistosome-infected subjects who were or were not coinfected with HIV were treated with praziquantel and followed up 3, 6, and 12 months after treatment. Quantitative measures of intensity of schistosomiasis (egg counts and levels of circulating anodic antigen in serum) and immunodeficiency (CD4+ cell counts and viral loads) were collected. Results. Cure rates based on egg counts 3 months after treatment were satisfactory and were similar for HIV-positive individuals (cure rate, 86%) and HIV-negative individuals (cure rate, 85%); the magnitude of decrease in egg count was equal. Cure rates based on circulating anodic antigen levels were much lower than cure rates based on egg counts, with HIV-positive individuals experiencing significantly less clearance of schistosomiasis (cure rate, 31%) than HIV-negative individuals (cure rate, 52%), whereas the magnitude of decrease in circulating anodic antigen was also lower among HIV-positive individuals (P<.01). Conclusion. The effect of praziquantel may be limited to affecting the fecundity of adult schistosomes in the immunocompromised host, thus reducing egg excretion while leaving schistosomes metabolically active, as shown by the fact that levels of antigen production are maintained. Special guidelines for treatment of schistosomiasis in HIV-coinfected individuals may need to be developed. [ABSTRACT FROM AUTHOR]

A recently reported epidemic of Schistosoma mansoni infection in Senegal provided an opportunity to study the dynamics of the development of immunity to human schistosomiasis. We report here on the cell-mediated immune response in a population of 99 females and 95 males, with particular emphasis on the relationship between intensity of infection and age. We found that the intensity of infection correlated negatively with age in females but not in males. In men and women, both Th1- and Th2-type cytokines were detected upon in vitro stimulation of PBMCs with soluble egg antigen (SEA) or soluble adult worm antigens (SWAP). In the female group, SEA-induced PBMC proliferation was associated with the production of IFN-gamma, IL-2 and IL-5, all of which correlated negatively with intensity of infection. Most cytokine production correlated positively with age. Spontaneous production of TNF-alpha, IL-6 and IL-10 was higher in the infected population than in an uninfected control group. Our results suggest that immunity to infection could be more pronounced in the female population and associated with a Th0/1 + 2 pattern of cytokine secretion mediated by soluble egg antigen (SEA). [ABSTRACT FROM AUTHOR]

The interaction in vitro between human lymphocytes and fixed C3 was inhibited by fluid phase C3b and C3c prepared by trypsinization of purified human C3. These C3 fragments suppressed in vitro transformation of human lymphocytes by specific antigens, PPD and Candida albicans somatic antigen, but not by phytohaemagglutinin, a non-specific mitogen. These observations indicate the form of C3 which interacts with complement receptor lymphocytes and suggest that this interaction may play a part in lymphocyte activation by antigen. [ABSTRACT FROM AUTHOR]

Incubation of eosinophils with schistosomula of Schistosoma mansoni in vitro induces changes in the eosinophil membrane. Cell surface proteins were blocked with unlabelled iodide and then, after incubation with schistosomula. newly accessible proteins were detected by lactoperoxidase catalysed iodination with radioactive iodide. Normal turnover restores several proteins to the eosinophil surface, but the schistosomula .specifically induced the appearance of a protein of mol. wt 18K. This protein has previously been detected when eosinophits interact with antibody coated agar layers. Soluble factors released by schistosomula induced the appearance of enhanced levels of 16 and 18K proteins. It has previously been shown that proteins involved in binding of eosinophils to IgG coated antigen coupled cellulose have mol. wts of 16K and 18K. [ABSTRACT FROM AUTHOR]