An Epstein-Barr virus-transformed B cell line produces autoregulatory interleukin-1 that regulates bone remodeling

In this study, we demonstrate that an Epstein-Barr virus-transformed B cell line, A-11, produced interleukin-1 (IL-1), a cytokine that regulates bone remodeling. A-11 cells produce IL-1 in a cell dose- and culture time-related manner. The IL-1 activity was neutralized by recombinant human IL-1 (rhIL-1) alpha antiserum, but not by rhIL-1 beta antiserum. The IL-1 was semi-purified by (NH4)2SO4 precipitation, Superose prep 12 gel filtration, and anion-exchange chromatography strongly stimulated in vitro bone resorption. The stimulatory effect of the purified IL-1 on bone resorption was prostaglandin independent. Purified IL-1 inhibited DNA and collagen synthesis in the osteoblastic cell line MC3T3-E1. However, it enhanced significantly the cellular activity of alkaline phosphatase (EC 3.1.3.1), a marker enzyme for differentiation of osteoblasts. On the other hand, A-11 cell proliferation was inhibited by addition of rhIL-1 alpha antiserum, but not by rhIL-1 beta antiserum. And cell proliferation was stimulated by exogenous rhIL-1 alpha and -beta.