Immunoregulation by CD4 T cells in the induction of specific immunological unresponsiveness to alloantigens in vivo: evidence for a reduction in the frequency of alloantigen-specific cytotoxic T cells in vitro.
Donor-specific unresponsiveness to allogeneic cardiac allografts in mice can be induced by the combined pretreatment with donor alloantigen and anti-CD4 antibody (anti-CD4+DST). We have investigated whether the induction of unresponsiveness in this model is due to the presence of T cells that regulate immune responsiveness towards the allograft. First, we analysed the functional characteristics of splenocytes from pretreated mice at the time of transplantation. A significant reduction in the frequency of donor specific cytotoxic precursor was found only after the anti-CD4+DST treatment. Next, we designed an in vitro assay to identify the phenotype of the splenocyte population responsible. CD4+ and CD4- fractions were purified from mice treated with anti-CD4+DST or anti-CD4 alone (controls) by cell sorting. Interestingly, only the addition of CD4+ cells from anti-CD4+DST treated mice resulted in a selective reduction and a bimodal distribution in the donor specific CTLp response, indicating the presence of a regulatory population. CD4+ cells from controls did not have this effect. These in vitro findings were substantiated by adoptive transfer experiments in vivo. These data demonstrate that CD4+ cells with the ability to regulate immune responsiveness to a cardiac allograft are present at the time of transplantation following pretreatment with donor alloantigen in combination with anti-CD4.
Roelen
D L
DL
Nuffield Department of Surgery, University of Oxford, John Radcliffe Hospital, United Kingdom.
Bushell
A R
AR
Niimi
M
M
Young
N T
NT
Rust
N A
NA
Morris
P J
PJ
Wood
K J
KJ
D019264:Adoptive Transfer; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D015704:CD4 Antigens / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000637:transplantation; D016027:Heart Transplantation / Q000276:immunology; D007108:Immune Tolerance; D007519:Isoantigens / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D015704:CD4 Antigens; D007519:Isoantigens