IMMUNE-RESPONSES DURING HUMAN SCHISTOSOMIASIS MANSONI .6. INVITRO NONSPECIFIC SUPPRESSION OF PHYTOHEMAGGLUTININ RESPONSIVENESS INDUCED BY EXPOSURE TO CERTAIN SCHISTOSOMAL PREPARATIONS

  • 1 January 1979
    • journal article
    • research article
    • Vol. 122  (4) , 1447-1453
Abstract
Simultaneous in vitro exposure of human peripheral blood mononuclear cells to phytohemagglutinin-P (PHA) and soluble schistosomal egg antigenic preparation (SEA) or soluble cercarial antigenic preparation (CAP) obtained from Schistosoma mansoni resulted in decreased responsiveness as compared to exposure to PHA alone. The addition of a soluble adult worm antigenic preparation (SWAP) did not predictably alter PHA responses in this system. The suppression due to in vitro exposure to SEA or CAP was expressed whether the lymphocyte donors were S. mansoni patients (early infection, chronic, or treated), or uninfected subjects. The degree of suppression was related to the concentration of SEA used and the timing of exposure. Pre-exposure to SEA for 3 days before the addition of PHA resulted in more potent suppression. A delay in the time of the addition of SEA of 6 and 24 h after PHA exposure decreased and eliminated, respectively, its suppressive capacity. SEA and CAP were not directly toxic to responding cells, and appeared to exert their nonspecific suppressive influences through T [thymus-derived] lymphocyte-related mechanisms. Although these suppressive events could be induced and observed in vitro, the responsiveness of S. mansoni patient lymphocytes to PHA was equal with that of uninfected controls.

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