An anti-adipocyte monoclonal antibody is cytotoxic to porcine preadipocytes in vitro and depresses the development of pig adipose tissue.

A mouse monoclonal antibody of the IgG2b subclass was raised against porcine adipocyte plasma membranes. This antibody did not cross-react in immunocytofluorescence with any tested cell-type or tissue other than porcine adipocytes. Complement-mediated cytotoxicity was demonstrated in primary cultures of porcine stromal-vascular cells. When the antibody and complement were added to already differentiated cultures, the treatment resulted in elimination of lipid-filled preadipocytes, whereas an early treatment of cultures prevented the appearance of these cells. In vivo, injection of newborn pigs with 1 mg/kg of monoclonal antibody on d 2 and 5 of life produced a more than 20% reduction of subcutaneous and leaf fat lipids at 35 d of age, whereas the lipid content of the longissimus muscle remained unaffected. These results demonstrate that early systemic treatment of pigs with a specific anti-adipocyte antibody reduces the fat mass. In addition to their potential in vivo use, monoclonal antibodies directed against adipose determinants may be useful tools for studying adipocyte lineage.