Regulatory Interactions Between Macrophages and T-Cell Subsets in Listeria monocytogenes-Specific T-Cell Activation

ABSTRACT

Peritoneal exudate T lymphocytes from Listeria monocytogenes-immune mice in the presence of the homologous antigen (heat-killed L. monocytogenes) and normal macrophages showed L. monocytogenes-specific proliferative responses. Proliferation was inhibited by macrophages from L. monocytogenes- or Corynebacterium parvum-pretreated mice as well as by exogenous prostaglandin E₂. Macrophage-dependent inhibition of T-cell proliferation—at least in part—could be reversed by addition of indomethacin. When selected L. monocytogenes-immune Lyt T-cell subsets were cultured in the presence of inhibitory macrophages, pretreatment with anti-Lyt 1 antiserum plus complement completely abrogated proliferation and pretreatment with anti-Lyt 2 and anti-Lyt 3 antisera plus complement markedly reduced proliferation. However, a mixture (1:1) of the two preselected Lyt T-cell subsets resulted in complete reconstitution of proliferative responses. In contrast, when L. monocytogenes-immune peritoneal exudate T lymphocytes were treated with anti-Lyt antisera plus complement after culture, only treatment with anti-Lyt 1 antiserum plus complement affected proliferation, suggesting regulatory interactions between Lyt 1⁺23⁻ and Lyt 1⁻23⁺ T cells during in vitro culture which result in proliferation within the Lyt 1⁺23⁻ T-cell subset. After rigorous depletion of residual macrophages and in the presence of indomethacin, pretreatment with anti-Lyt 1 antiserum plus complement, but not with anti-Lyt 2 and 3 antisera plus complement, eliminated proliferation. The data presented indicate that interactions between macrophages and Lyt T-cell subsets regulate L. monocytogenes-specific T-cell activation.