Characterization of a concanavalin A-induced amplifier T cell which augments in vitro antibody responses to DNP-Ficoll

Abstract

The addition of the T-cell mitogen concanavalin A (Con A) on Day 2 of a 4-day in vitro culture of murine spleen cells with the thymus-independent (TI) antigen DNP 39-Ficoll resulted in significant enhancement of the direct antitrinitrophenyl (TNP) plaque-forming cell (PFC) response. This enhancement was mediated by a nylon wool- and antiimmunoglobulin-nonadherent amplifier T cell (T A). T A activity was not eliminated by in vitro treatment of T cells with anti-Thy 1.2 and complement (C). T A activity could be eliminated by pretreatment of mice with antilymphocyte serum (ALS) in vivo, followed by in vitro treatment of T cells with anti-Thy 1.2 + C. Thus, T A appear to bear a low surface density of Thy-1 antigen. These T A were relatively resistant to ALS used alone, to cyclophosphamide, and to low dose in vitro irradiation. T A were still present in the spleen 14 weeks after adult thymectomy (ATx). They were I-J positive and apparently belonged to the Lyt 1 +2 − T-cell subset.