Isolation and preliminary characterization of human intestinal macrophages

Methods for the isolation and culture of macrophages from normal human intestine are described. After disaggregation using sequential treatments of dithiothreitol, ethylenediaminetetraacetate, collagenase, and deoxyribonuclease, Percoll density gradients (1.064 SG) produced single cell suspensions from which macrophages were readily purified by adherence to plastic. Macrophages were characterized by morphology, phagocytosis, cytoplasmic staining for nonspecific esterase, presence of membrane Fc receptors, Ia-like antigens, and lysozyme synthesis and secretion. In 10 separate experiments, recovery of viable mononuclear cells was 2.9 ± 0.6 × 106 cells/g of mucosa. Thirty percent of these cells were phagocytic. After adherence to plastic, the macrophage recovery was 1.05 ± 0.2 × 106 cells/g mucosa and 90% ± 0.4% of the adherent cells in the monolayer were phagocytic. Fifty-five percent of the adherent cells showed Fc receptors for immunoglobulin G, while 94% expressed the Ia-like antigen on their membrane. The successful isolation and culture of human intestinal macrophages in large numbers will allow detailed study of their role in the mucosal immune response in health and disease.