Expression of 5'nucleotidase activity and wheat-germ agglutinin binding sites in mononuclear phagocytes from bone marrow cultures.

The question as to whether the various types of mononuclear phagocyte found in bone marrow cultures and recognized by specific peroxidatic (PO) activity patterns differ in the expression of binding sites for the lectin wheat-germ agglutinin (WGA) and the activity of the ectoenzyme 5'nucleotidase (5'N) was investigated. Monoblasts, promonocytes, monocytes, and/or exudate macrophages, and exudate-resident macrophages generally showed a high level of WGA binding, and a considerably lower level was found in the PO-negative cells and in resident macrophages. 5'N activity was absent in monoblasts, promonocytes, and in the great majority of the monocytes and/or exudate macrophages, but was demonstrable in exudate-resident macrophages and resident macrophages, as well as in PO-negative macrophages after 4 days of culture. On the basis of the successive occurrence of the above-mentioned phenotypes in cultures, the possibility that this diversity in WGA binding and 5'N activity is related to modulation during cell differentiation is discussed. The present findings led to the conclusion that the PO-negative macrophages, whose origin was previously not entirely certain, are precursors of resident macrophages.