Mouse T cell clones against Mycobacterium avium: identification of clones that modify resistance against atypical mycobacteria infection.

Mouse T cell clones against live Mycobacterium avium were generated from the spleens of BALB/c mice infected with M. avium TMC 702. Eighth clones were of the L3T4+ subset, whereas two were of Lyt2+ subset. Six of the L3T4+ T cell clones were of the TH1 subset whereas two were of the TH2 subset, judged on the profile of cytokine release. One of the Lyt2+ clones exhibited significant cytotoxicity against M. avium-infected mouse macrophages. Transfer of clones to nude BALB/c mice infected with M. avium was associated with insignificant changes in resistance for seven clones. One clone, of the L3T4+/TH2 subset, transferred significant resistance to the infection, also associated with infusion of supernatants from the clone, which was fully inhibited by neutralizing with anti-interleukin 4. By contrast, infusion of one TH1 clone and the cytolytic Lyt2+ led to increased microbial growth in the spleens and livers of infected mice, which was not apparent on infusion with supernatants. Application of clones' supernatants on infected macrophages had marginal effects on M. avium growth and was not correlated with protective or suppressive activity. Overall, these results suggest that T cells may influence M. avium growth in vivo in a bidirectional manner and also suggest that interleukin 4 may be an important factor in host resistance to M. avium.