A function of CD10 on bone marrow stroma

Bone marrow (BM) stromal cells express CD10 (cALLA), a surface antigen now known to be a neutral endopeptidase (NEP-24.11). The function of CD10 in BM stroma is unknown, although purified NEP-24.11 is known to degrade different substrates including interleukin 1 beta (IL-1 beta). We have therefore employed a CD10-positive BM stromal cell line (L2AK) which proliferates in response to IL-1 beta to test the hypothesis that degradation of this cytokine is one of the functions of stromal CD10. We first showed that [3H]thymidine incorporation by L2AK cells is enhanced by IL-1 beta in a clear dose-dependent manner. Addition of the CD10 inhibitor, phosphoramidon, together with IL-1 beta resulted in a left shift in the dose-response curve which corresponded to a 10-fold potentiation of the IL-1 beta effect. These results indicate that CD10 on bone marrow stromal cells can degrade IL-1 beta and therefore provide a local control of the effects of this, and possibly other, growth factor(s).