Kinetics of anti-CD4-induced T helper cell depletion and inhibition of function. Activation of T cells by the CD3 pathway inhibits anti-CD4-mediated T cell elimination and down-regulation of cell surface CD4.
In vivo treatment with anti-CD4 antibody profoundly suppresses a number of T cell-dependent responses and is clinically useful in the treatment of certain mouse models of autoimmune disease. Treatment with anti-CD4 antibody will inactivate and can deplete CD4 T cells, but the mechanisms responsible for these effects are incompletely understood. When mouse spleen cells were exposed in vitro to both SRBC and monoclonal anti-CD4, there was 55% reduction of the anti-SRBC response. If cultures were preincubated with anti-CD4 for 48 h before in vitro challenge, the reduction was greater than 80%. When unfractionated spleen cells were cultured with anti-CD4 for 96 h, there was actual elimination of CD4 cells in these cultures since virtually all CD3+ cells were CD8+. Activation of T cells by exposure to anti-CD3 rendered them resistant to antibody-mediated CD4 depletion. This resistance to CD4 depletion was seen even in cultures that were pretreated with anti-CD4 for as long as 24 h before anti-CD3 exposure. In cultures of purified T cells, anti-CD4 did not eliminate CD4 T cells. However, culture of T cells with macrophage-rich adherent cells and anti-CD4 resulted in elimination of CD4 T cells. Thus, it appears that macrophages play a role in anti-CD4-induced T cell elimination. While anti-CD4 did not eliminate CD4 cells from a population of purified T cells, there was profound down-regulation of cell surface CD4. Activating T cells with immobilized anti-CD3 before addition of anti-CD4 prevented down-regulation of CD4. These experiments demonstrate that T cell activation by anti-CD3 renders the activated cells resistant to antibody-induced CD4 down-regulation and to antibody-induced CD4 T cell depletion. These findings may have relevance to the application of anti-CD4 therapy in human diseases that are mediated by activated Th cells.
Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52242.
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I
Jamali
E H
EH
Field
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Fleming
J S
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Cowdery
D000937:Antigen-Antibody Reactions; D000945:Antigens, Differentiation, T-Lymphocyte / Q000502:physiology*; D017252:CD3 Complex; D015704:CD4 Antigens / Q000276:immunology* / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D015536:Down-Regulation; D007518:Isoantibodies / Q000276:immunology*; D008213:Lymphocyte Activation; D008212:Lymphocyte Depletion; D008264:Macrophages / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000502:physiology*; D013154:Spleen / Q000166:cytology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*; D013997:Time Factors
D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D015704:CD4 Antigens; D007518:Isoantibodies; D011948:Receptors, Antigen, T-Cell