AN IN-VITRO MODEL FOR IMMUNE CONTROL OF CHLAMYDIAL GROWTH IN POLARIZED EPITHELIAL-CELLS

A polarized epithelial culture system and chlamydia-specific T-cell fi nes and clones were employed to investigate the ability and mechanisms by which T cells control the growth of chlamydiae in epithelial cells . Monolayers of polarized mouse epithelial cells were infected with th e Chlamydia trachomatis agent of mouse pneumonitis (MoPn) and then exp osed to antigen-stimulated MoPn-specific T-cell lines and clones. The results revealed that in vivo-protective MoPn-specific T-cell lines an d clone 2.14-0 were capable of inhibiting the growth of MoPn in polari zed epithelial tells. In contrast, the nonprotective MoPn-specific T-c ell clone 2.14-3, naive splenic T cells, and a control T-cell clone co uld not inhibit the growth of MoPn in epithelial cells. Transmission e lectron microscopic analysis of infected epithelial cells which were e xposed to clone 2.14-0 confirmed the absence of an established infecti on, as deduced from the virtual absence of inclusions in the cells. An tigen-specific activation of clone 2.14-0 was required for the MoPn-in hibitory function, since the absence of antigenic stimulation or stimu lation with a heterologous chlamydial agent did not result in MoPn gro wth inhibition. Activation of clone 2.14-0 resulted in acquisition of the capacity to inhibit growth of both homologous (MoPn) and heterolog ous chlamydial agents. Close interaction between epithelial cells and clone 2.14-0 was required for the MoPn-inhibitory action, because sepa ration of the cell types by a filter with a pore size of 0.45, 3.0, or even 8.0 mu m abrogated MoPn inhibition. Protective T cells may act a t close range in the epithelium to control chlamydial growth, possibly involving short-range-acting cytokines. The ability of antigen-stimul ated T-cell lines and clones to inhibit chlamydial growth in polarized epithelial cultures could be a useful method for identifying protecti ve T-cell clones and antigenic peptide fragments containing protective epitopes.