Characterization of polyclonal antibodies to cell-surface antigens from ovine adipose tissue.

High titres of polyclonal antibodies to specific proteins of ovine adipose tissue plasma membranes were raised in horses and chickens following repeated injections of purified plasma membranes. Horse antiserum was highly species specific, reacting only weakly with rat adipose tissue plasma membranes. A protein of molecular weight 68,000 was most antigenic in that it was readily precipitated; however proteins of 25,000, 82,000 and 94,000 were also precipitated when the reaction was performed for longer with a higher antiserum concentration. Chicken egg yolk IgY reacted strongly with ovine adipose tissue plasma membranes as did those preparations from horse, but IgY was ineffective in immunoprecipitating solubilized membrane proteins and exhibited no cytotoxic reaction when incubated with intact ovine adipocytes. However, horse antiserum produced a strong complement-dependent cytotoxic reaction with ovine adipocytes, as measured by leakage of lactate dehydrogenase. This work suggests that the membrane protein of molecular weight 68,000 is likely to be an important antigenic marker for ovine adipocytes.