Relation between the increase of circulating CD3+ CD57+ lymphocytes and T cell dysfunction in recipients of bone marrow transplantation
Some patients undergoing bone marrow transplantation (BMT) persistently present increased proportions of circulating CD57+ T cells. We analysed the cell surface phenotype in peripheral blood mononuclear cells (PBMC) from 69 allogeneic and 11 autologous BMT recipients. In parallel samples from 49 patients, the proliferative response to T cell mitogens was assessed, either in the presence or absence of exogenous interleukin‐2 (IL‐2). PBMC samples from long‐term allogeneic BMT patients with increased proportions of CD57+ cells displayed significantly (P < 0.001) lower proliferative responses, compared with samples from patients with normal proportions of CD57+ cells and from healthy subjects. Elimination of the CD57+ population by C′‐dependent lysis did not normalize the proliferative response. After positive selection by cell sorting. CD57+ cells responded poorly, but in the presence of IL‐2 the proliferation appeared to be similar to that displayed by the CD57‐ subset and still suboptimal compared with normal controls. These data suggest that the hyporesponsiveness to mitogenic stimuli in the presence of exogenous IL‐2 of PBMC from allogeneic BMT recipients cannot be simply attributed either to the putative suppressor activity of CD57+ cells, or to a poor proliferative capacity of this subset. Supporting this notion we report that PBMC from long‐term autologous BMT recipients containing high proportions of CD57+ T cells respond normally to T cell mitogens.