Effect of mycobacterial lipids on membrane fluidity and natural killer cell-mediated cytotoxicity

A total lipid fraction was extracted from BCG and used for the lipid modulation of effector and target cells in relation to the effect of mycobacterial lipid on human natural-killer(NK)-cell-mediated cytotoxicity. Treatment of the cells with the lipid fraction resulted in decreased membrane fluidity and inhibition of NK-cell-mediated cytotoxicity irrespective of whether the targets or the effectors were treated. These results were obtained in the chromium release assay and the single cell assay. Pretreatment of target cells did not affect binding between target and effector cells, whereas pretreatment of effectors resulted in inhibition of conjugation. These results are discussed with respect to known effects of lipid modulation of target and effector cells on NK-cell-mediated cytotoxicity and of mycobacterial lipids on immune responses.