Regulation of interleukin-6 expression in the lymphoma cell line OCI-LY3

Previously we described a cell line OCI-LY3 derived from a patient with non-Hodgkin's lymphoma. The cell line produced interleukin-6 (IL-6) mRNA and protein and demonstrated an autocrine pattern of growth for IL-6. Southern blot analysis of the IL-6 gene did not reveal any rearrangement. To determine whether the production of IL-6 by OCI-LY3 was due to subtle changes in the promoter of IL-6 or due to the expression of trans-acting factors chloramphenicol acetyltransferase (CAT) reporter constructs containing from -1,180 to +13 to -112 to +13 of a normal IL-6 gene were electroporated into the cell line. When these constructs are transferred into unstimulated fibroblasts, no CAT activity is seen; however, CAT activity is induced when the cells are stimulated with either IL-1 alpha, lipopolysaccharide (LPS), or cyclic adenosine monophosphate (cAMP) analogues. When the cell line OCI-LY3 was transfected with these constructs, CAT activity was observed; it was not necessary to stimulate the cells with exogenous factors to observe this activity. No CAT activity was observed in a second lymphoma cell line, OCI-LY13.1, that does not produce IL-6. These results suggest that the constitutive production of IL-6 by the cell line OCI-LY3 is due to the presence of trans-acting factors that stimulate the expression of IL-6 and not due to a cis-acting mutation of the IL-6 promoter.