AN EX-VIVO STUDY OF T-LYMPHOCYTES RECOVERED FROM THE LUNGS OF I ST MICE INFECTED WITH AND SUSCEPTIBLE TO MYCOBACTERIUM-TUBERCULOSIS/

I/St mice, previously characterized as susceptible to Mycobacterium tu berculosis H37Rv, were given 10(3) or 10(5) CFU intravenously, At two time points postinoculation, the cell suspensions that resulted from e nzymatic digestion of lungs were enumerated and further characterized phenotypically and functionally, Regarding the T-cell populations reco vered at 2 and 5 weeks postinfection, two main results were obtained: (i) the population of CD44(-) CD45RB(+) cells disappeared within 2 wee ks postinfection, while the number of CD44(+) CD45RB(-/low) cells slow ly increased between weeks 2 and 5; (ii) when cocultured with irradiat ed syngeneic splenocytes, these lung T cells proliferated in the prese nce of H37Rv sonicate, Using H37Rv sonicate and irradiated syngeneic s plenocytes to reactivate lung T cells, we selected five CD3(+) CD4(+) CD8(-) T-cell clones. In addition to the H37Rv sonicate, the five clon es react to both a short term culture filtrate and an affinity-purifie d 15- to 18-kDa mycobacterial molecule as assessed by the proliferativ e assay. However, there was a clear difference between T-cell clones w ith respect to cytokine (gamma interferon [IFN-gamma] and interleukin- 3 [IL-4] and IL-10) profiles: besides one Th1-like (IFN-gamma(+) IL-4( -)) clone and one Th0-like (IFN-gamma(+) IL-4(+) IL-10(+)) clone, thre e clones produced predominantly IL-10, with only marginal or no IL-4 a nd IFN-gamma responses. Inhibition of mycobacterial growth by macropha ges in the presence of T cells was studied in a coculture in vitro sys tem, It was found that the capacity to enhance antimycobacterial activ ity of macrophages fully correlated with INF-gamma production by indiv idual T-cell clones following genetically restricted recognition of in fected macrophages. The possible functional significance of cytokine d iversity among T-cell clones is discussed.