HUMAN-B CELL INTERLEUKIN-10

Interleukin 10 (IL-10) is a novel lymphokine which exhibits strong DNA and amino-acid sequence homology to BCRF1, an open reading frame in t he Epstein-Barr virus genome. Using a wide panel of EBV positive and E BV negative cell lines, it has been shown that EBV positive B cell lin es derived from patients with AIDS and Burkitt's lymphoma (AABCL) secr ete large quantities of B cell IL-10, compared-with EBV-positive B cel l lines obtained from patients with undifferentiated lymphomas of Burk itt's and non-Burkitt's types. In contrast, EBV-negative B cell lines do not express IL-10 by Northern blot analysis, ELISA or even PCR. B c ell IL-10 is confined to a narrow window in the B cell differentiation pathway, and whereas IL-10 expression is detected in mature and prepl asmacytic stages, none of the pro-B, pre-B, or myeloma cell lines prod uce IL-10. EBV exerts direct effect on the production of B cell IL-10, and purified tonsillar B cells infected with EBV were triggered to se crete IL-10. The large amount of IL-10 secreted by B cells derived fro m AIDS-related lymphomas suggests that HIV-1 also exerts direct effect on IL-10 secretion. B cell IL-10 may function as autocrine growth fac tor for B cell lymphomas, and both IL-10 and BCRFI seem to be involved in the pathophysiology of non-Hodgkin's lymphomas.