Abnormalities of in vitro responses to polyclonal activation of peripheral blood lymphocytes in patients with active sarcoïdosis

Abstract. A variety of immunological abnormalities have been described in patients with sarcoïdosis. At the blood level, both hypo and hyper immune responsiveness seem to coexist and were related to abnormal T cell and macrophage functions by using allogenic cocultures and/or lymphocyte fractionation. We tested several components of cell mediated responses with two in vitro models: (a) the pokeweed mitogen activation of B cells which is T cells and macrophage dependent; (b) the Epstein-Barr virus (EBV) activation of B cells which is T cell- and macrophage-indepen-dent. We confirm previous data showing that PWM induced Ig Production of peripheral blood lymphocytes (PBL) of patients with sarcoïdosis is significantly reduced compared with normal PBL. However, this is associated with an increase of IgG, IgM synthesis of EBV-infected PBL in these sixteen patients. Thus, there is no evidence for a complete B cell defect in sarcoïd PBL. Furthermore, by using limiting dilution analysis of antibody secreting cells, there is an increase of precursor B cells EBV infectable in PBL of sarcoïd patients but T cells are effective in reducing EBV-induced B cell proliferation. Finally, these abnormalities are concomitant to the disease, disappear with it, and are apparently not correlated with the stage or the activity of sarcoïdosis.