Reticuloendothelial Fc receptor function in SLE patients. II. Associations with humoral immune response parameters in vivo and in vitro.

We studied the relationship between reticuloendothelial Fc receptor function and some parameters of the humoral immune response in vivo and in vitro in 18 SLE patients. Fc receptor-mediated immune clearance correlated remarkably well with (a) a decrease of antigen specific IgG after immunization with a primary test antigen (alpha-Helix pomatia haemocyanin) (P less than 0.01) and (b) the spontaneous IgG release in vitro of B cells obtained from peripheral blood (P less than 0.01). These two parameters were significantly interrelated. Reticuloendothelial Fc receptor function was not related to serum IgG levels. The study provides evidence for an association between polyclonal B cell activation and Fc receptor-mediated immune clearance in SLE patients. The possible nature of this association is discussed.