PEANUT AGGLUTININ .1. NEW TOOL FOR STUDYING LYMPHOCYTE-T SUB-POPULATIONS

Abstract

Fluorescein-coupled peanut agglutinin (PNA) was used at the single-cell level to study mouse lymphocyte subpopulations. PNA binds to most thymocytes and also binds to a small fraction of peripheral lymphocytes that are all T [thymus derived] (.theta.+Ig- [immunoglobulin negative]) or null cells (.theta.-Ig-). Most PNA-positive thymocytes are sensitive to in vivo corticosteroids and irradiation (450 rads) treatments. The positive spleen cells (5% of total spleen lymphocytes) are essentially resistant to corticosteroids and irradiation. Study of PNA binding during ontogenesis shows the occurrence of PNA-positive cells in the fetal liver before thymus constitution and in the very beginning of embryonic thymus and spleen development. PNA is a marker of early T cell subpopulations but there are probably several distinct subsets of PNA-positive T cells.