Proliferation and immunoglobulin secretion of lymphoblastoid cell lines are differently affected by soluble cytokines

Abstract. The aim of our study was to investigate whether supernatant from lipopoly‐saccharide‐activated monocytes (monocyte‐factor) and/or cytokines could enhance secretion of human monoclonal antibodies specific to HLA antigens produced by Epstein—Barr virus lymphoblastoid cell lines (EBV‐LCLs). In a low cell density culture system, the monocyte‐factor significantly stimulated cell growth of three monoclonal and two polyclonal EBV‐LCLs while no enhancement of immunoglobulin production was observed. The enhancement of proliferation was completely neutralized by an antiserum to human IL‐6 suggesting that IL‐6 was required for the stimulation of growth of LCLs. The effect of cytokines on proliferation showed large variations among the cell lines, with IL‐lβ generally inducing the highest response. Of the cytokines tested, only IL‐2 was able to enhance total immunoglobulin secretion due to the induction of a higher production of light chains. The specific anti‐HLA activity was slightly increased by IL‐10 although this cytokine had no effect on total immunoglobulin concentration or proliferation.