In vivo study of the immunomodulating activity of OM-85 using the plaque-forming cells technique (PFC) in mice.

The activity of increasing oral doses of the bacterial extract OM-85 was determined by using the plaque-forming cells assay in mice. The results showed that the oral administration of OM-85 significantly increased the number of splenic antibody-secreting cells against sheep red blood cells (antigen) compared with controls. A maximal response was reached between 400 and 800 mg/kg body weight, and was reproducible with the different batches of OM-85 used. This study indicates that the oral administration of the immunomodulator allows the activation of splenic B-lymphocytes, probably through the gut-associated lymphoid tissue.