Asunto(s)
Linfocitos T CD4-Positivos/inmunología , Enfermedades Reumáticas/inmunología , Artritis Reumatoide/inmunología , Antígeno CTLA-4/metabolismo , Enfermedad Crónica , Humanos , Tolerancia Inmunológica , Proteína Coestimuladora de Linfocitos T Inducibles/metabolismo , Interleucina-2/metabolismo , Activación de Linfocitos , Receptor de Muerte Celular Programada 1/metabolismo , Receptores de Antígenos de Linfocitos T/metabolismo , Espondiloartritis/inmunologíaRESUMEN
Treatment of PBMC with the CD4-specific mAb BT-061 induces CD4 down-modulation of T cells. Here we report that addition of BT-061 to purified T cells did not confer this effect, whereas incubation of T cells in BT-061 coated wells restored CD4 down-modulation. These results implied that Fcγ receptor mediated cell-cell interactions played a role. In consistence with this hypothesis PBMC depleted of CD64(+) monocytes did not confer CD4 down-modulation of BT-061 decorated T cells. Strikingly, CD4 down-modulation was observed in BT-061 treated synovial fluid punctuated from patients' inflamed joints that comprised enhanced numbers of CD64(+) cells. In contrast, in a circulating whole blood system injection of BT-061 did not induce CD4 down-modulation, due to CD64 saturation by serum IgG. Similarly, tonsil derived mononuclear cells devoid of CD64(+) cells did not show CD4 down-modulation, whereas addition of blood derived monocytes restored the effect. Thus, the interaction of BT-061 decorated T cells with CD64(+) cells is needed for CD4 down-modulation, implying that in patients BT-061 would primarily induce CD4 down-modulation at inflammatory sites. These results highlight the need not only to examine the interaction of a given mAb with single FcγR, but also the immunological environment that is appropriate to support such interactions.