Serum soluble CD23 level correlates with subsequent development of AIDS-related non-Hodgkin's lymphoma

The cytokine soluble CD23 (sCD23) has been shown to act as a B cell growth factor and to be elevated in serum prior to development of AIDS-related non-Hodgkin's lymphoma (AIDS NHL). To further characterize the elevation of serum sCD23 in AIDS NHL patients and investigate its potential as a diagnostic test, a matched case-control study of AIDS NHL (n = 101) was nested within the Multicenter AIDS Cohort Study. Serum sCD23 was measured in cases' and controls' serum specimens at three different time periods (0-6, 6-12, and 12-18 months) and CD4+ thresholds (0-99, 100-199, and 200-299 cells/microl) prior to the case's NHL diagnosis. Changes in serum sCD23 over time were examined in AIDS NHL cases relative to controls, and t tests were performed to determine whether cases' serum sCD23 exceeded that of controls at each time period and CD4+ threshold. Overall, cases' median serum sCD23 levels were approximately double those of controls. Serum sCD23 concentration was positively correlated with lymphocyte counts for both cases and controls. The difference in cases' and controls' serum sCD23 levels became greater as AIDS NHL diagnosis date approached: in the 18 months preceding the case's NHL diagnosis, serum sCD23 was stable in cases but dropped in controls. Although this difference was statistically significant (P < 0.05), it was not clinically significant. It is unlikely that serum sCD23 would make a useful test for AIDS NHL because the magnitude of the difference between cases and controls was small and there was no change in serum sCD23 in cases that would indicate disease.