Monoclonal antibody EBM/11: high cellular specificity for human macrophages

A monoclonal antibody, EBM/11, was raised against isolated human lung macrophages. Immunohistochemically this antibody reacted with freshly isolated lung macrophages and blood monocytes, mononuclear cells (presumptive macrophages) in sections of lung, skin, stomach, small and large bowel, pancreas, spleen, tonsil, placenta, liver, gall bladder, heart, thyroid, pituitary, brain, and peritubular and mesangial cell in kidney. Microglial cells and osteoclasts also labelled with EBM/11. The antibody reacted with cytoplasmic structures rather than with cell membranes. The epitope recognised by EBM/11 was present on four polypeptides (of 120, 70, 64 and 22 kilodaltons). It did not react with any other cell type in the tissues screened except the epithelium of renal proximal tubules. This antibody may be useful in identifying and elucidating the function of macrophages in pathological processes.