Immunomodulating activities of Corynebacterium xerosis cell-wall fractions

Corynebacterium xerosis cell-wall fractions were studied by electron microscopy and analysed for immunomodulating activity. Dramatic splenomegaly occurred following the injection of whole cells or a purified cell-wall fraction (PF), but not with a further purified peptidoglycan (PEP) fraction. Both PF and PEP acted as B-cell mitogens and had adjuvant capabilities comparable to commercial adjuvants. Only the PF fraction enhanced peritoneal natural killer cell (NK) activity, paralleling the splenomegaly response. When spleens from mice injected with PF or PEP were analysed for their abilities to respond to mitogens and for the presence of suppressor cells, reduced mitogenic responses occurred only in PF-injected mice during the peak of splenomegaly. Spleens from both PF- and PEP-injected mice contained suppressor cell activity which peaked 2 weeks post-injection. This activity was primarily directed at B-cell responses to lipopolysaccharide (LPS). C. xerosis cell-wall fractions thus offer great potential as a new immunomodulator.