UC Irvine

High levels of lymphotoxin-like activity (LT) were found in supernatants from secondarily stimulated immune mouse splenocytes activated with concanavalin A (Con A) in vitro. Splenocytes obtained from C57Bl/6 mice immune to the P815 mastocytoma were restimulated in vitro with mitomycin C-treated P815 cells, and then stimulated with Con A. High levels of unstable LT activity are rapidly (2-4 hr) released by these lectin-stimulated splenocytes. The introduction of a crosslinking agent, glutaraldehyde, was found to stabilize this LT activity and allowed us to perform more defined biochemical studies and to examine the functional activities of the LT classes. The lytic activity in these supernatants resided in the high-molecular-weight classes, termed Complex (Cx > 200,000 daltons) and alpha-heavy (αH 130,000-160,000 daltons). It was found that the Cx and αH LT classes from the secondarily stimulated immune splenocytes cause lysis of allogeneic target cells, P815 and EL-4, in a 16-hr 75Semethionine release assay, and in some cases, this lysis was specific for the sensitizing target cell. © 1981.