T-cell abnormality and defective interleukin-2 production in patients with carcinoma of the urinary bladder with schistosomiasis.

Patients with schistosomiasis of the urinary bladder (SB) and schistosomiasis with carcinoma of the urinary bladder (SCB) had significantly increased percentage of IL-2R-, HLA-DR-, and transferrin receptor (T9)-bearing T cells in circulation. The percentage of these activated T cells decreased by in vitro culture with PHA but increased by Schistosoma haematobium soluble egg antigen. These patients with SB and SCB had a PHA-specific defect in IL-2 production. A functional defect with induction of IL-2R-positive suppressor monocytes appears to correlate with the defective PHA-induced IL-2 production by CD4+ T cells and monocytes. Disordered regulation of PHA-induced IL-2 production by the CD4+ T cells and monocytes may be the key feature in the highly depressed cell-mediated immune response in schistosomiasis. However, immune activation and significantly elevated IL-2 production in response to disease-specific S. haematobium soluble egg antigen may be related with the pathogenesis of SB and SCB. Thus, S. haematobium-specific CD4+ T cells are present in schistosomiasis, and their function is determined by adequate release of IL-2-and/or IL-2R-bearing CD11+ suppressor monocytes.