title: Drug-induced immunological unresponsiveness: selective inhibition of T-cell 'helper function' by cyclophosphamide in mice pretreated with phytohaemagglutinin.
abstract: Studies involving the combined use of phytohaemagglutinin (PHA) and cyclophosphamide (CY) indicate that both agents can act together to produce immunological unresponsiveness: following injection of PHA into mice, splenic DNA synthetic responses [14C]thymidine incorporation) and haemolysin plaque formation against sheep red blood cells were determined in daily intervals. Both immunosuppression and DNA synthetic activity were maximally developed 5 days after treatment with PHA. Administration of CY at this time resulted in immunological unresponsiveness lasting for about 18 days. Antibody production could be completely restored with antigen-activated T cells (but not with B cells), thus indicating a selective inhibition of T-cell 'helper function' in mice treated with PHA and CY. This observation is consistent with the general assumption that cells involved in the response to PHA are predominantly T cells. Apparently, these cells are highly sensitive to an inactivation by CY after stimulation with PHA.
mesh_terms: D000328:Adult; D000818:Animals; D000917:Antibody Formation / Q000187:drug effects*; D003520:Cyclophosphamide / Q000494:pharmacology*; D004247:DNA / Q000096:biosynthesis; D005260:Female; D006462:Hemolytic Plaque Technique; D006801:Humans; D037102:Lectins / Q000494:pharmacology*; D008213:Lymphocyte Activation / Q000187:drug effects; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D013154:Spleen; D013601:T-Lymphocytes / Q000276:immunology; D013997:Time Factors
chemical_list: D037102:Lectins; D003520:Cyclophosphamide; D004247:DNA