B-CELL-INDEPENDENT SELECTION OF MEMORY T-CELLS AFTER MUCOSAL IMMUNIZATION WITH CANDIDA-ALBICANS

B cell-deficient mice have normal T cell responses to Ags inoculated s ystemically; however, it is not known whether they can mount systemic and mucosal T cell responses to Ags through normally B cell-enriched g astrointestinal mucosae, Mucosal colonization of germfree, B cell-defi cient J(H)D mice with the pathogenic gastrointestinal fungus, Candida albicans selected splenic CD4(+) and CD8(+) TCR alpha beta memory T ce lls, as indicated by 1) increased numbers of splenic CD4(+) and CD8(+) TCR alpha beta expressing T cells of the CD45RB(low)CD44(high) phenot ype, 2) early expansion followed by progressive decrease in the number of splenic CD4(+) and CD8(+) TCR alpha beta T cells, and 3) concomita nt increases in the percentage of apoptosis and proliferation in the l atter subsets, Although i.v. challenge of germfree or conventional J(H )D mice with C. albicans did not increase apoptosis or induce changes in the number of splenic memory T cells, i.v. challenge of mucosally i mmunized germfree J(H)D mice led to further proliferation and expansio n of activated splenic CD4(+) and CD8(+) TCR alpha beta thymic-educate d memory T cells, which were first evoked by mucosal immunization, Ora l colonization with C. albicans also increased the number of gamma del ta and thymic and extrathymic alpha beta T cells in gastrointestinal m ucosae, In conclusion, our results are the first strong evidence that thymic and extrathymic T cells participate in mucosal immunity to C. a lbicans in the absence of B cells; however, CD4(+) and thymic-educated CD8(+) TCR alpha beta memory subsets evoked by mucosal, but not paren teral (i.v.), challenge contribute to protective immunity to systemic candidiasis.