A monoclonal antibody specific for mouse dendritic cells.

Abstract

Dendritic cells (DC) are a small subpopulation of lymphoid cells with distinctive cytologic features, surface properties and functions. The DC-specific antibody (Ab) secreted by clone 33D1 is described. Rat spleen cells immune to mouse DC were fused to the mouse P3U myeloma. Hybrid culture supernatants were screened simultaneously against DC, a macrophage (M.PHI.) cell line [mouse J774 tumor cells] and mitogen-stimulated lymphoblasts. 33D1 Ab specifically killed 80-90% of DC from spleen and lymph node, but no other leukocytes, including Ia+ and Ia- M.PHI. (Ia, I-region-associated antigen). Quantitative binding studies with 3H-labeled 33DI Ab showed that DC had an average of 14,000 binding sites per cell. Binding to DC was inhibited with Fab fragment of 33D1 Ab but not with a panel of other monoclonal antibodies, including anti-Ia Ab. Adherence and flotation procedure that enriched for DC enriched for 3H-labeled 33D1 Ab binding in parallel. 33D1 antigen was not detectable on: M.PHI. from spleen, peritoneal cavity, and blood; 3 M.PHI. cell lines [J774, P388D1, RA264.7 cells]; lymphocytes; granulocytes; platelets; and erythroid cells. DC continued to express the 33D1 antigen after 4 days in culture, whereas M.PHI. and lymphocytes did not acquire it. Quantitative and autoradiographic studies confirmed that spleen and lymph node suspensions contain less than 1% DC. 33D1 Ab apparently detects a stable and specific DC antigen and can be used to monitor DC content in complex lymphoid mixtures.