CD8+ T lymphocytes in intracellular microbial infections

Specificity of proliferative response of human CD8 clones to mycobacterial antigens

Human CD8 T lymphocyte clones (TLC) were generated from the pleural effusion of patients with tuberculosis using a protocol that required, in addition to antigen, coculture of purified CD8+ T cells, accessory cells, interleukin 2 (IL2) and anti-CD3-Sepharose. The TLC obtained were stimulated by mycobacterial soluble extracts in an IL2-dependent and MHC class I-restricted manner. When antigen-responsive TLC were screened with extracts from the recombinant mycobacterial library they were found to respond to either the Y3125 (100-kDa) or the Y3111 (71-kDa) lambda gt11 clones. Polyacrylamide gel immunoblot analysis demonstrated that the CD8 TLC responded to fractions with the molecular mass range 27-45 kDa in the Y3125 lysogen and 60-90 kDa in the mycobacterial soluble extract. The specificity of TLC reactive with the Y3111 clone was confirmed using the 71-kDa antigen purified from the same lysogen. These TLC recognized sequences common to the 71-kDa protein derived from mycobacteria, E. coli or a human cell line. Studies of three TLC using antigen-presenting cells of known genetic haplotype indicated that stimulation with both the Y3125 and the 71-kDa antigens were restricted by determinants encoded by HLA-B8.

The recombinant 65-kD heat shock protein of Mycobacterium bovis Bacillus Calmette-Guerin/M. tuberculosis is a target molecule for CD4+ cytotoxic T lymphocytes that lyse human monocytes

Since little is known about Tc cells in the human immune response to intracellular parasites, we have studied the role of Tc cells in response to M. bovis Bacillus Calmette-Guerin (BCG). Donors whose PBMC responded to BCG, purified protein derivative (PPD), and the recombinant 65-kD heat shock protein (HSP) of BCG generated BCG/PPD-specific CD4+ effector T lymphocytes that lysed PPD as well as recombinant 65-kD-pulsed monocytes. Nonpulsed or irrelevant antigen-pulsed target cells were lysed to a much lower but still significant extent. PPD-stimulated effector lymphocytes of a recombinant 65-kD nonresponder lysed PPD but not recombinant 65-kD-pulsed monocytes. Recombinant 65-kD-educated effector lymphocytes lysed both recombinant 65-kD- and PPD-pulsed monocytes. In addition, these effector cells efficiently lysed nonpulsed target cells. These results demonstrate that in recombinant 65-kD responders, the recombinant 65-kD HSP of BCG is an immunodominant target as well as a triggering molecule for BCG/PPD-specific CD4+ cytotoxic T cells that lyse autologous monocytes. The implications of these findings with respect to the role of the 65-kD HSP in autoimmunity are discussed.