Serum alpha interferon and lymphocyte inclusions in systemic lupus erythematosus

The relationship between serum acid-labile alpha interferon and tubuloreticular inclusions within the cytoplasm of circulating lymphocytes was studied in 46 patients with systemic lupus erythematosus. Elevated levels of interferon (greater than or equal to 8 IU/ml) were found in 17 patients and lymphocyte inclusions in 35. The mean serum interferon concentration in patients with lymphocyte inclusions was significantly higher than in patients without inclusions (17.2 versus 2.4 IU/ml, p less than 0.01). Inclusions were found in 16 of 17 patients with elevated interferon and also in 19 of 29 patients without interferon (p = 0.026). In lupus, serum interferon appears to be a sufficient though not an essential marker for the presence of lymphocyte inclusions.