DEVELOPMENTAL RELATIONSHIP BETWEEN CYTOTOXIC ALPHA BETA T-CELL RECEPTOR-POSITIVE INTRAEPITHELIAL LYMPHOCYTES AND PEYER PATCH LYMPHOCYTES/

Following intraduodenal priming of mice with reovirus, precursor cytot oxic T lymphocytes (pCTL) rapidly appear in intraepithelial lymphocyte s (IEL) and Peyer's patches. These cells express CTL activity after se condary in vitro stimulation with reovirus-infected cells. Adoptive tr ansfer of Peyer's patch lymphocytes from normal BALB/c mice into reovi rus-infected CB. 17 severe combined immunodeficiency mice results in t he infection-dependent appearance of large numbers of both CD8+Thy-land CD8-Thy-l+, IEL that express the alpha/beta T cell receptor (TcR). Phenotypic and functional characterization of IEL derived from conven tionally reared, reovirus-infected mice also points to extensive simil arities in the pCTL derived from Peyer's patches and IEL. As in the Pe yer's patches, pCTL are persistent in the IEL compartment for up to 4 weeks after infection. A large percentage of IEL that are recovered fr om reovirus-primed mice after in vitro culture are CD8+Thy-1+ cells th at express alpha/beta TcR. Furthermore, depletion experiments demonstr ate that the CD8+Thy-1+ population mediates the virus-specific CTL act ivity. Using limiting dilution analyses, it was estimated that 7 days after intraduodenal infection the average frequency of virus-specific pCTL was 197/10(6) CD8+Thy-l+ IEL and 190/10(6) CD8+Thy-l+ Peyer's pat ch lymphocytes. Taken together, these observations provide evidence th at specific cellular immunity to reovirus in IEL is mediated, at least in part, by conventional cytotoxic T lymphocytes and that these cells are functionally and phenotypically similar to the pCTL derived from the Peyer's patches.