Cellular immune responses of hydatid patients to Echinococcus granulosus antigens.

The reactivity of peripheral blood mononuclear cells (PBMC) from 40 hydatid patients to hydatid fluid (HF) and to two hydatid fractions (pH5PPT and pH5SUP) was evaluated by the incorporation of 3H-methylthymidine into DNA. Maximal responses were detected using 200 micrograms/ml protein after 7-9 days incubation. The three antigen preparations were inducers of PBMC proliferation, with a good correlation (r2 = 0.87) of the responses induced by HF and by the fraction pH5PPT, which contains the two major hydatid antigens (5 and B). Lymphocytes from healthy donors and non-hydatid patients showed no response to these antigens. Neither direct nor inverse correlation was found between the results of the serological tests and of the PBMC proliferation assays. The majority of the patients (75%) responded in serological and in cellular tests. Of the remaining patients, six showed high antibody response associated with a negative PBMC proliferation assay and conversely four seronegative patients were found to respond positively in the PBMC proliferation assay. No relationship of the pattern of immune responsiveness to the patient's clinical forms could be established. Use of the PBMC proliferation assay with hydatid antigens appears rational in those patients which are low antibody producers, but the test is still not to be considered applicable for routine diagnosis.