Immune responses and immunoregulation in relation to human schistosomiasis in Egypt. I. Effect of treatment on in vitro cellular responsiveness

Cell mediated immune reactivity of chronic schistosomiasis patients was tested in vitro by peripheral blood mononuclear cell (PBMN) responses against phytohemagglutinin P (PHA), Candida albicans extract, soluble schistosomal antigenic preparations derived from eggs (SEA), adult worms (SWAP) and cercariae (CAP), before and after treatment of the patients with parziquantel. The patient population was from villages in the Qalyub province, Egypt, that are endemic for Schistosoma mansoni and S. haematobium. Patients were studied immediately before, and at 1, 3, 6, and 9 months after chemotherapy. Egg counts were done on stool and urine specimens taken simultaneously with blood samples. There was a significant increase in PBMN responses to SWAP and CAP but not to SEA, PHA or C. albicans in 27 patients (age 8-65) 1 month after treatment. Eleven patients treated 1.5 years previously did not show such elevated responses 1 month after re-treatment. Three months after treatment higher mean responses were observed to SWAP, CAP, SEA, and PHA, but not to C. albicans in 24 patients (age 6-26). Significant increases in PBMN responses to SWAP and CAP, but not to SEA, PHA or C. albicans were obtained at 6 months after treatment in 12 patients (age 6-30). By 9 months after treatment in a group of 11 patients (age 8-25) SWAP and CAP responses were still elevated as were SEA and C. albicans induced reactivities. The PBMN responses of 10 patients were followed longitudinally at pretreatment, 3-, 6-, and 9-month post-treatment times. In general, elevated responses were maintained throughout this period to the schistosomal preparations. Unrelated responses occasionally fluctuated but were not consistently altered over time.