Detection of human T cells using anti-monkey thymocyte antisera. Tissue distribution and evidence for antigenic heterogeneity

Six rabbit anti-monkey thymocyte antisera (AMT) were superior reagents to antisera prepared against human thymocytes, thymocyte membranes, and fetal brain with respect to absorption requirements and fluorescence brilliance on human T lymphocytes. The distribution of T cells in adult subjects was defined using fluorescein-labeled AMT absorbed for T-cell specificity. This reagent reacted with 96% of thymocytes, 75% of peripheral blood lymphocytes, 63% of thoracic duct lymphocytes, 40% of splenocytes, 55% of lymphocytes from intraabdominal lymph nodes, and 13% of nucleated cells flushed from bone marrow. T antigens detected by AMT were expressed on virtually all fetal thymocytes and a minority of fetal spleen cells as early as 13 weeks of gestation. By absorbing AMT with a cultured T-cell line (MOLT-4), it was possible to distinguish a subpopulation of T cells displaying antigen(s) not present on MOLT-4. This subpopulation comprised the majority of thymocytes, one-half of peripheral-blood T cells, but only one-third of splenic or lymph-node T cells. A quantitative absorption assay failed to demonstrate cross-reactivity of AMT with antigens in homogenized human brain or a preparation of brain synaptasomes.