The Activation of C3H/HeJ Cells by Certain Types of Lipopolysaccharides

Abstract

Experimentation with the endotoxin non-responder C3H/HeJ mouse has provided considerable insight into the genetic control of the pathophysiological and immunobiological effects induced by lipopolysaccharide endotoxin (LPS); however, the mechanism underlying this deficiency has never been fully elucidated. At the cellular level much of the research has focused on the B-lymphocyte of the C3H/HeJ strain. Although it is known that C3H/HeJ B-cells can respond to protein mitogens (8, 13, 14), there is no conclusive evidence that typical protein-free LPS or lipid A can stimulate DNA synthesis or polyclonal antibody production by these cells equivalent to that seen with normal responder cells. However, recently several reports have appeared indicating that C3H/HeJ spleen cells in culture could be stimulated by certain forms of LPS to proliferate to some extent. By gel filtration chromatography, Vukajlovich and Morrison prepared homogeneous monomeric components of E. coli 055:B5 LPS (17). One of these fractions, which was protein-free, enriched in lipid A and contained a trace of 0-antigen, induced a significant but limited amount of ³H-thymidine incorporation by C3H/HeJ splenic lymphocytes as compared to responder C3HeB/FeJ cells (17). Vogel et al., (16) reported that a lipid A precursor obtained from a temperature sensitive mutant of S. typhimurium was active for C3H/HeJ B-cells and macrophages although the preparation contained a trace of protein. In contrast, the lipid X precursor of Raetz et al., (10) from E. coli failed to stimulate C3H/HeJ cells although it is a polyclonal B-cell activator (PBA) for LPSresponder cells. With the advent of synthetic lipid A, studies on its activity and various analogues were initiated with responder and non-responder cells. Kumazawa et al., (3) reported that one non-posphorylated derivative containing 3-hydroxytetradecanoic acid stimulated ³H-thymidine uptake 3 to 6-fold in C3H/HeJ spleen cells although the net cpms were half that obtained with C3H/HeN responder cells. Synthetic lipid A as well as all of the other derivatives which were monophosphorylated, diphosphorylated, or nonphosphorylated and contained various mixtures of myristic and hydromyristic acids were inactive on C3H/HeJ cells (3). Finally, Girard et al., (2) reported that the LPS from B. pertussis was active in stimulating C3H/HeJ splenic lymphocytes to proliferate but the activity was ascribed to the polysaccharide components rather than the lipid A.