Peripheral blood lymphocytes of patients with common variable immunodeficiency (CVI) produce reduced levels of interleukin-4, interleukin-2 and interferon-gamma, but proliferate normally upon activation by mitogens.

Peripheral blood lymphocytes (PBL) of 11 patients with CVI produced reduced levels of interleukin-4 (IL-4) upon activation by mitogens as compared with those secreted by PBL of healthy donors. The interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) production by PBL of a series of 15 patients with CVI was also reduced. Decreased levels of IL-4 or IL-2 and IFN-gamma production were not only observed after activation by phytohaemagglutinin (PHA) at concentrations of 10 and 1 micrograms/ml, but also after activation by concanavalin A (Con A, 10 micrograms/ml). Longitudinal studies indicated that this defective lymphokine production was consistent upon testing periods up to 5 months. No correlation between reduced IL-4, IL-2 or IFN-gamma production was observed. PBL of patients that produced reduced levels of one lymphokine generally secreted normal levels of the other two lymphokines. Despite the reduced synthesis of the T cell growth factors IL-2 and IL-4, the proliferative responses of the PBL of the patients were in the normal range, which is compatible with the finding that IL-2 and IL-4 have synergistic effects on lymphocyte proliferation, particularly when one of these lymphokines is present at suboptimal concentrations. Since IL-2, IL-4 and IFN-gamma can act as B cell growth and differentiation factors, our data suggest that the reduced synthesis of these lymphokines may contribute to the deficient immunoglobulin production in patients with CVI.