IL6 AND IL6 RECEPTOR EXPRESSION IN BURKITTS-LYMPHOMA AND LYMPHOBLASTOID CELL-LINES - PROMOTION OF IL6 RECEPTOR EXPRESSION BY EBV

We have analysed a panel of different Burkitt's lymphoma (BL) and lymp hoblastoid cell lines (LCLs) for the expression of IL6 and IL6 recepto r (IL6R). Epstein-Barr-Virus (EBV) positive or negative BL cell lines and the corresponding lymphoblastoid cell lines (LCL), derived from EB V immortalized mononuclear cells of the BL patients, were tested for t he expression of IL6 mRNA and protein by Northern blot experiments and ELISA, and for the expression of the IL6R mRNA and protein by Norther n blot Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) and fl ow cytometry. Our results demonstrate that six out of 19 Burkitt's lym phoma cell lines produced IL6 constitutively. All three cell lines inf ected with the EBV substrain B95-8 (B95-8 convertants) produced IL6, i n contrast to the original EBV negative lines and to the cell lines in fected with the EBV substrain P3HR1 (P3HR1 convertants). The produced IL6 was biologically active as shown by proliferation of the IL6 depen dent cell line TEPC 1033 C2. The two BL cell lines with the highest le vel of IL6 production (190 pg/ml and 550 pg/ml) expressed in addition IL6R molecules on the cell surface. Monoclonal antibodies directed aga inst IL6 did not inhibit the growth of these two BL cell lines, thus e xcluding autocrine stimulation in these lines. IL6R expression could b e further demonstrated in all LCLs analysed, in five out of seven EBV positive BLs and two out of three B95-8 convertants, but only in one o ut of the six EBV negative BL cell lines. Our results suggest that EBV in immortalized B cells and in Burkitt's lymphoma cells can promote I L6 receptor expression.