SUBPOPULATIONS OF MOUSE RESIDENT PERITONEAL-MACROPHAGES FRACTIONATED ON PERCOLL GRADIENTS SHOW DIFFERENCES IN CELL-SIZE, LECTIN-BINDING ANDANTIGEN EXPRESSION SUGGESTIVE OF DIFFERENT STAGES OF MATURATION

Aiming the identification of macrophage heterogeneity, mouse resident peritoneal cells were fractionated on discontinuous Percoll gradients into six discrete fractions (0, 1, 2, 3, 4 and 5 in order of increasin g density), All six fractions and the total population were characteri zed by light and electron microscopy, and flow cytometry, The least de nse fraction (0) had a low viability (44%); fractions 4 and 5 had a lo w percentage of macrophages. Light microscopy and flow cytometry of ma crophage-enriched fractions 1, 2 and 3 showed an inverse correlation b etween diameter and cell density, as well as suitable differences in l ectin binding to the macrophages of each fraction, The surface of macr ophages from fraction 1 had more sialyl residues (higher binding of th e lectin LFA), less galactosyl residues (lower binding of the lectin P NA) and expressed more receptors for the antibodies M1/70 (Mac-1) and F4/80; fraction 3 had an opposite binding behavior for the lectins and expressed fewer receptors for both antibodies; fraction 2 had an inte rmediate behavior for both parameters, Binding of the lectins Con A an d HPA showed slight differences, whereas UEA I did not present a detec table difference among the fractions analyzed, These findings suggest that the macrophage heterogeneity achieved by the gradient separation of resident peritoneal cells could be explained by different stages of macrophage maturation.