THE MR 95,000 GELATIN-BINDING PROTEIN IN DIFFERENTIATED HUMAN MACROPHAGES AND GRANULOCYTES

  • 1 January 1985
    • journal article
    • research article
    • Vol. 65  (5) , 1175-1180
Abstract
Cultured adherent human macrophages and a promonocytic cell line, U 937, were previously shown to produce a MW 95,000 gelatin-binding protein. The protein has no immunologic cross-reactivity with the well-characterized gelatin-binding protein fibronectin and the MW 70,000 gelatin-binding protein produced by a variety of mesenchymal or epithelial cell types. The MW 95,000 protein was found in Triton X-100 extracts of granulocytes purified from human blood buffy coat. The protein, as isolated by gelatin-agarose, was immunologically cross-reactive with corresponding macrophage protein in immunoblotting assay. When peripheral blood and bone marrow cells were examined for the presence of the MW 95,000 protein by indirect immunofluorescence, positive staining was detected only in differentiated granulocytes but not to any significant extent in metamyelocytes, myelocytes, promyelocytes, or in normal or leukemic blasts. In granulocytes the protein had a granular cytoplasmic distribution. In freshly prepared monocyte cultures, the MW 95,000 protein was detected in low amounts in the cytoplasm, while along with differentiation of the cells into macrophages, the immunofluorescence increased in a reticular and vesicular cytoplasmic pattern and in a juxtanuclear cap, probably representing the Golgi complex. In conclusion, the MW 95,000 gelatin-binding protein was specifically detected in macrophages and granulocytes and may serve as a differentiation marker for these phagocytic cells.