Expression and complex assembly of calcium‐binding proteins MRP8 and MRP14 during differentiation of murine myelomonocytic cells

In the present study we analyzed expression and biochemical properties of the two recently cloned calcium-binding proteins MRP8 and MRP14, both mem- bers of the S-iOO family, in murine myelomonocytic cells. Expression of MRPs was found to be restricted to granulocytes and distinct stages of macrophage differenti- ation when compared to the expression of other markers (Mac-i, F4180) in transformed macrophage cell lines (Mi, RMB.TG, WEHI.TG, J774A, P388D) and resident and exudate peritoneal and tissue macrophages. Similarly, mRNA and protein levels of MRP8/MRP14 in murine bone marrow cells decreased during culture in L cell-con- ditioned medium. Applying a cross-linking technique, the formation of noncovalently associated heteromeric MRP8/MRP14 complexes of 25, 35, and 48 kd was demonstrated. Our data suggest that MRP8/MRP14 ex- pression and complexation are characteristic for granulo- cytes and distinct stages of macrophage differentiation in mice. Analysis of the MRP8/MRP14� phenotype of mac- rophages may provide further insights into the mechan- isms underlying macrophage differentiation. J. Leukoc. Biol. 53: 11-18; 1993.