[Possible mechanisms of implementation of toxic potential of lipopolysaccharides of pathogenic bacteria].
The significance of variability of biological properties of lipopolysaccharides (LPS) is discussed in the paper within the pathogenesis of infectious process. On the basis of an analysis of published data and of results of independent research of two microorganisms (Yersinia pestis and Francisella tularensis) a conclusion is made on that a biologically inert LPS form (with a weak cytokine-inducing ability, apirogenicity and non-toxicity etc.) is typical of highly pathogenic bacteria. It is suggested that the above phenomenon is biologically expedient. Presumably, the inert LPS transforms to the active form inside a sensitive host and, according to an infection stage, each of them being functionally significant. It is the inert status of LPS that enables the pathogens, at the initial stages, to surmount freely the humoral and cell barriers of host. As the infection progressively aggravates and the proliferation of bacteria modifies itself due to LPS micro- and macroorganisms, its chemical structure and biopolymer conformation change. Both modification mechanisms enhance the LPS toxic potential. In case of a sensitive host, such variations transform the biologically inert LPS into a toxically active form with its function of endotoxin being realized. There is no LPS modification in a host insensitive to such infection, which entails either recovery or prolonged persistence of the pathogen inside the microorganism.