Transfer of immunity by means of spleen cells from mice immunized with outer membrane proteins of Shigella flexneri.

Intraperitoneal immunization of mice with a single dose (5 micrograms) of outer membrane proteins (OMP) of Shigella flexneri was found to evoke in the spleen the appearance of cells by means of which immunity to lethal dose of Shigella could be transferred into other mice. Active cells capable of transferring immunity appeared in the spleen of the animals as early as on day 3, reached the strongest protective activity on day 4 and disappeared on day 8 after immunization. Active cells from animals immunized with two doses of OMP maintained in the spleens for 19 days. The experiments revealed that immunity to Shigella could be transferred only with lymphocytes; macrophages were found to be inactive.