Effect of outer membrane proteins of Shigella on delayed hypersensitivity in mice to sheep red blood cells.

Small doses of outer membrane proteins (OMP) of Shigella flexneri injected intraperitoneally into mice 1 to 3 days before or 3 days after sensitization of animals with sheep erythrocytes were found to increase delayed hypersensitivity as measured by the footpad reaction. In contrast, administration of higher doses of OMP resulted in suppression of hypersensitivity response. Cell transfer experiments showed that the spleen cells from sensitized and OMP treated mice transferred stimulating and suppressing activity to normal recipients. Suppression of hypersensitivity was also observed when recipients were injected with OMP 24 h before they were infused with spleen cells obtained from donor mice sensitized with sheep erythrocytes.