CD11b/c. OX-42 recognizes three major polypeptides of 160 kDa, 103 kDa and 95 kDa and a minor 133 kDa protein under non-reducing conditions. Under reducing conditions two major peptides of 163 kDa and 100 kDa and a minor 135 kDa peptide are detected. Antigen distribution: Isolated cells: OX-42 shows a similar reaction pattern to OX-41 on various isolated cells but stains bronchial lavage cells to a lesser degree. OX-42 inhibits complement mediated rosettes. Tissue sections: OX-42 is a most suitable marker for the identification of microglial cells and Kupffer cells. It also stains dendritic cells strongly. Only a subpopulation of alveolar macrophages is recognised. Specificity: Rat: granulocytes, macrophages, microglial cells. Other species: not tested