IMMUNOMODULATORY SPECTRUM OF LIPIDS ASSOCIATED WITH MYCOBACTERIUM-AVIUM SEROVAR-8

Lipid fractions obtained from Mycobacterium avium serovar 8 were asses sed for the ability to affect various immune functions of human periph eral blood mononuclear cells (PBM). Lipids included a total lipid frac tion and fractions eluted from silicic acid column separation of that total lipid fraction, using chloroform and chloroform methanol combina tions. Lipid fractions were assayed for total carbohydrate and total 6 -deoxyhexose content and were assessed for the ability to influence hu man macrophage function and the capacity to induce secretion of prosta glandin E(2) (PGE(2)) and tumor necrosis factor alpha in PBM. The tota l lipid and serovar-specific glycopeptidolipid (GPL) fractions both in duced significant levels of tumor necrosis factor alpha, as well as PG E(2), in PBM exposed to a sublethal concentration of 100 mu g lipid pe r 2 x 10(6) cells. In addition, the same concentrations of the 5 to 7% and GPL fractions induced significant levels of leukotriene B4 in PBM . Comparison of carbohydrate and 6-deoxyhexose contents of each fracti on suggested a relationship to carbohydrate content and ability of fra ctions to induce immune modulator secretion, Analysis of GPL fractions from ill. avium serovars 4 and 20 revealed that those GPL lacked the ability to induce PGE,, These results are explained by considering the difference in the carbohydrate residues of the oligosaccharide moieti es.