Functional properties of lectin-induced thermostable SE rosette (TSER)-forming cells derived from human peripheral blood.

Mitogens are able to stimulate T cells in human peripheral blood lymphocyte cultures to form thermostable rosettes with sheep erythrocytes (TSER). Previously we characterized TSER-forming cells as BL/T2-, DR- and 4F2-positive, e.g. activated T lymphocytes. In this study the evidence is presented that mitogen-induced TSER-forming cells are the responding, proliferating lymphocytes. We studied the sequential activation of human lymphocytes by various mitogens. PHA-induced TSER-forming cells could not been further activated neither by PWM nor by Con A. DNA synthesis rate in Con A-preactivated lymphocytes was enhanced by PHA but not by PWM. PWM-induced TSER-forming cells, however, were further activated as well by PHA as by Con A. These data suggest the heterogeneity of the pathways by which different mitogens activate human immune cells. PWM- and PHA-induced TSER-forming cells could support B lymphocyte differentiation, when PWM was added to the cultures, whereas Con A-preactivated cells failed, indicating different functional activities induced by mitogenic lectins.