Interleukin-5 is an autocrine growth factor for Epstein-Barr virus-transformed B lymphocytes.
Because of the recent finding that interleukin-5 (IL-5) is produced by Epstein-Barr virus-transformed B lymphocytes (EBV-B cells), we performed studies to ascertain whether EBV-B cells might use IL-5 by an autocrine mechanism. EBV-B cells known to be IL-5 producers were capable of responding to addition of exogenous IL-5 by dose-related augmented proliferation. The addition of a neutralizing anti-IL-5 antibody reduced these effects and also dose-dependently inhibited proliferation and reduced viability of unsupplemented EBV-B cells, having a maximum effect at about 120 hours. In contrast, no stimulatory effect of IL-5 was noted on Burkitt's lymphoma cell lines, nor were these lines growth-inhibited by anti-IL-5 antibody. With biotinylated IL-5, (b-IL-5) second labeling with streptavidin-FITC, and flow cytometric analysis, binding of IL-5 to EBV-B cells cultured in fresh medium was demonstrated and could be competed for by excess unlabeled IL-5, suggesting the presence of IL-5-specific binding sites. Binding of IL-5 was reduced on cells cultured for longer periods before study but could be restored by extensively washing cells before labeling them with b-IL-5, suggesting that surface binding sites had become occupied by endogenously produced IL-5. These findings support a role for IL-5 in autocrine support of EBV-B cell growth.
Baumann
M A
MA
Department of Medicine, VA Medical Center, Dayton, OH 45428.
Paul
C C
CC
D000906:Antibodies; D001402:B-Lymphocytes / Q000166:cytology* / Q000378:metabolism; D001667:Binding, Competitive; D002455:Cell Division; D002461:Cell Line, Transformed; D005434:Flow Cytometry; D006133:Growth Substances / Q000494:pharmacology*; D004854:Herpesvirus 4, Human; D006801:Humans; D015848:Interleukin-5 / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000494:pharmacology
D000906:Antibodies; D006133:Growth Substances; D015848:Interleukin-5; D011994:Recombinant Proteins