Influence of RU 41.740, a glycoprotein extract from Klebsiella pneumoniae, on the murine system. II. RU 41.740 facilitates the response to Con A in otherwise unresponsive T-enriched cells.

RU 41.740, a glycoprotein extract from Klebsiella pneumoniae, is a polyclonal B cell activator in the thymus-independent category, and both RU 41.740 and its fraction F1 induce the production of interleukin 1 (IL 1). RU 41.740 alone appears to have no direct effect on T-enriched cells. However, we show here that when given in conjunction with concanavalin A (Con A), RU 41.740 enabled nylon wool-passed T cells, which had been accessory cell depleted and lost responsiveness to Con A, to proliferate in response to Con A. Analysis of this observation indicated that RU 41.740 probably acted via a residual accessory cell population and that contact of this cell with the T cell was necessary for Con A activation of the T cell. Because both lectin/antigen and a source of IL 1 are required to stimulate accessory cell-depleted T cells, the mechanism of action of RU 41.740 in this system may be by induction of IL 1 from residual accessory cells in the nylon wool-passed, T-enriched cell population. However, two other agents that stimulate IL 1 production, lipopolysaccharide (LPS) and F1, do not enable T-enriched cells to respond to Con A in this system.