Mitogenic response to Micropolyspora faeni cell walls.

Three cell wall fractions, prepared from Micropolyspora faeni, were shown to be mitogenic for the splenic lymphocytes of unsensitized guinea pigs. This response peaked after 48 hr in culture and was dose dependent. Using enriched lymphocyte subpopulations obtained by column-separation techniques, it was shown that the most active cell wall fractions were primarily B cell mitogens. Physical, chemical, and enzymatic digestion studies indicated that the heat-stable mitogenic reactivity was associated with polypeptide and polysaccharide. The reactive material is, at least in part, peptidoglycan, as shown by the decrease in its mitogenic potential after lysozyme digestion. A possible host-related role for this mitogenic reactivity was discussed.