Influence of burn-induced lipid-protein complex on IL2 secretion by PBMC in vitro

Normal peripheral blood mononuclear cells (PBMC) were incubated with the lectins PHA and ConA to stimulate IL2 release into the culture supernatants. In the added presence of the lipid protein complex (LPC) derived from burned skin, PHA and ConA produced much less bioavailable IL2, the combination with PHA being more inhibitory of its production than that with ConA at concentrations of 1 μg and 5 μg lectin/ml. As LPC alone also elicited IL2 production the inhibition of active IL2 production with these lectins was seen as a synergistic reaction with LPC. This was not altered by incubating cells with PHA alone, followed later by LPC, suggesting that LPC affects later molecular events which develop in T-cell activation. However, after incubating LPC first and washing it from the cells, both lectins were able to stimulate secretion of higher levels of bioavailable IL2, but again, less IL2 was produced with PHA than with ConA. Since PHA and ConA are reported to react with the T-cell receptor (TCR) and CD3 T-cell surface antigens, respectively, although both react additionally with CD2, it appears that LPC interfered more directly with TCR-related reactions than those involving CD3, although the two antigens have been considered to be interdependent. LPC is a trimer of a complex of six proteins from skin cell membranes, which had coalesced under the influence of thermal energy. The six proteins have relative molecular weights of 40, 50, 65, 110, 120 and 160 kDa. By coincidence 40 kDa and 51 kDa are the weights of the heterodimer subunits of TCRα/β, and CD2 is 50 kDa. Human heat shock proteins of 65 kDa and 110 kDa are also known. If skin-derived antigen recognition receptors, from CD3 + cutaneous lymphocytes, together with heat shock proteins, are indeed part of LPC it could explain how LPC from burn eschar could impair the normal T-cell responses in the severely burned patient. This possibility is discussed.