Cytoplasmic proteins of porcine adipocytes: identification with monoclonal antibodies

In the present study, monoclonal antibodies were produced using porcine adipocyte extracts as the immunogen. Two of the monoclonal antibodies, designated CB6 and IB4, exhibited reactivity toward only cells containing lipid in stromal-vascular cell cultures. The antigens recognized by the CB6 and IB4 monoclonal antibodies were 50 kD and 55 kD proteins, respectively. In vivo, IB4 immunoreactivity was detected only in lipid-containing cells, whereas immunofluorescence using CB6 was also detectable around muscle fiber bundles underlying the subcutaneous mesenchyme. In fetal subcutaneous mesenchyme, CB6 and IB4 immunoreactivities toward lipid-containing cells increased with developmental age, but each was not detectable in cells containing the smallest lipid droplets. In stromal-vascular cultures containing adipocytes, 48 hour treatment with the anti-lipogenic agent, growth hormone, only slightly altered CB6 immunoreactivity, whereas IB4 immunoreactivity was reduced by more than sixfold. The exact identity of the CB6 and IB4 antigens was not determined, but each may be useful as markers for studying regulation of adipocyte metabolism.