FIG. 3.

Proliferative T-cell responses to various Yersinia-specific antigens after oral immunization with wild-type or mutant Yersinia strains. Splenic T cells were stimulated with 10 μg of heat-killed Y. enterocolitica (HKY), Yersinia heat shock protein (YHSP60), and recombinant Yersinia outer proteins (YopD, YopE, YopH, and the V antigen) or without Yersinia antigen. Proliferative responses are expressed as SI. Solid bars represent SI values of T cells stimulated with the indicated antigen, whereas open bars represent SI values of T cells exhibiting non-antigen-stimulated (spontaneous) proliferation. Values are the means of triplicate cultures, with standard deviations indicated by error bars. ∗, value differs from that of the control (P < 0.05).