In patients with common variable immunodeficiency, interleukin-6 and expression of its receptor on B-cells are normal.

In a group of patients suffering from common variable immunodeficiency (CVID), levels of interleukin-6 (IL6) were measured and found to be in the normal range or even increased, for single patients. IL6 production of peripheral blood mononuclear cells was shown to be in the normal range when corrected for monocyte number. To exclude the possibility that the Interleukin-6 receptor (IL6R) on B-cells is missing, its expression was measured by assessing the binding of a Phycoerythrin-derivative of IL6 by flow cytometry and correlated with various markers for B-cells and T-cells. As compared with normal controls, no statistically significant deviation of the group as a whole nor for individual patients could be shown. It was concluded that lack of B cell differentiation in the presence of normal to high IL6 as shown for these patients is not due to inability of the B cells to detect IL6 in the serum.