Fluoresceinated anti human T cell reagents from monkey and human sources

Four antigen (Ag) sources were evaluated for producing fluoresceinated (F1) antihuman T cell heteroantisera: human thymocytes (HT), human thymocyte membranes (HTM), human brain, and monkey thymocytes (MT). Antisera raised from each Ag source, except brain, contained T cell specific antibodies (Ab). However, both HT and HTM antisera required 10-12 absorptions using 7 different tissue sources to remove nonspecific Ab. MT antisera cross reacted well with human T cells while minimal nonspecific reactivity was removed by 2 absorptions with a cultured B lymphocyte line (RAJ1). After absorption, T cell specificity of each F1 reagent was determined by: labeling of 95-100% HT and 50-65% human peripheral blood lymphocytes (PBL), absent staining to cells not containing T Ag (cultured B cells, fibroblasts, Burkitt lymphoma, B leukemia cells, fetal liver), absent staining to rhodamine labeled B cells in PBL using a double label assay, removal of T cell reactivity by prior HT absorption, and blocking of nonimmune E rosette formation. Absorption by human brain failed to remove T cell Ab. Thus, thymocytes contain multiple Ag specificities, but antisera against MT require far fewer absorptions than antihuman thymocyte reagents to achieve human T cell specificity. A relevant T cell Ag on MT is less species specific than other determinants shared by T and B lymphocytes.