Flow cytometric analysis of IL-6 receptors on peripheral lymphocytes in patients with primary biliary cirrhosis.

Interleukin-6 receptors (IL-6R) and interleukin-1 receptors (IL-1R) on lymphocyte surfaces were analyzed, using flow cytometry and dye-labeled IL-6 and IL-1 beta, to examine the clinical and immunological significance of these receptors. Incubation of peripheral blood mononuclear cells in the presence of mitogen resulted in a remarkable increase of lymphocytes expressing the IL-6 and IL-1 beta receptors on the cell surface. The increase in lymphocytes bearing these cytokine receptors may reflect an increase in stimulated lymphocytes. When peripheral blood from patients with primary biliary cirrhosis (PBC) was examined for these receptors, the percentage of IL-6R positive cells was significantly higher in the patients than in healthy controls (P < 0.01). The increase in IL-6R positive cells was only significant for the T lymphocyte fraction (P < 0.01). No significant change in IL-1R was observed. There was a significant positive correlation between the percentage of IL-6R positive T lymphocytes and the titer of antimitochondrial antibody in patients with PBC. These findings concerning IL-6R may be noteworthy elucidating autoimmune etiological features of PBC.