Abstract
We demonstrated earlier that bacterial endotoxins (lipopolysaccharides, LPS) have the capacity to activate both pathways of complement, with the polysaccharide portion of the molecule activating the alternative pathway and the lipid A region being responsible for classical pathway activation (Morrison, D. C. and Kline, L. F., 1977, J. Immunol. 118:362). We further showed that only preparations of LPS which initiate alternative pathway activation are capable of LPS-initiated complement-dependent rabbit platelet lytic responses. (Morrison, D. C. et al., 1976, Fed. Proc., 35:516).
Although the lipid A region of the LPS molecule is, itself, incapable of initiating lysis, our current experiments provide strong evidence that it does, in fact, play a critical role in the rabbit platelet response to LPS. Treatment of LPS with mild alkali (using conditions known to enhance binding of LPS to both erythrocytes and lymphocytes) significantly enhanced the extent of the complement-mediated platelet lysis.
