IL-10 and IL-4 co-operate to normalize in vitro IgA production in IgA-deficient (IgAD) patients.

In the present study we evaluated in vitro immunoglobulin production from IgAD individuals and healthy controls. Peripheral blood mononuclear cells (PBMC) from IgAD and controls were cultured with anti-CD40 MoAb presented on a CDw32-transfected fibroblast cell line (CD40 system) in the presence of IL-10, IL-2, IL-4, transforming growth factor-beta (TGF-beta) alone as well as of IL-10 in combination with each of the other three cytokines. Only IL-10 added alone induced significant changes in baseline immunoglobulin production; marked increases in median supernatant levels of all three isotypes were observed in both groups. The most striking finding of this study was the synergizing effect of IL-4 on IgA production in the IgAD group when added with IL-10; median IgA supernatant level increased to a value superimposable on that found in the normal controls which remained about the same as when stimulated with IL-10 alone. The synergic effect of IL-4 and IL-10 was specific to the IgA isotype.