Immunohistochemical detection of monocytes by the antiserum specific to monocytic esterase.

An antiserum specific to esterase Ib was produced in a rabbit. The antigen-antibody reaction was visualized by the strong esterase activity in the precipitin band in Ouchterlony double diffusion and immunoelectrophoresis. Immunohistochemical procedure demonstrated strong staining in the monocyte-infiltrated splenic sections and tissue sections of true histiocytic lymphoma. Negative results were observed in T- and B-cell lymphomas, granulocytic sarcoma, and chronic granulocytic leukemia. This antibody may be useful for the identification of monocytes and histocytes in paraffin-embedded tissue sections.