INTERNALIZATION OF HUMAN MACROPHAGE SURFACE-ANTIGENS INDUCED BY MONOCLONAL-ANTIBODIES

Drugs intended to be endocytosed by macrophages may be transported by MAbs directed against these cells. Twenty MAbs were investigated for t his purpose. The binding of these MAbs to macrophages obtained from a 7 day culture of blood monocytes showed that anti-CD11b and anti-CD14 recognized the highest number of cell surface antigen sites. Further a ssays determined that anti-CD63, Mo5 and anti-CD33 were the MAbs that induced the strongest modulation of the corresponding antigens, the hi ghest rate being with anti-CD63. Endocytosis of antigen-antibody compl exes was evidenced by the presence of MAbs in the cytoplasm. Anti-CD63 MAbs induced the highest internalization in this assay. For most MAbs , however, the density of antigen sites and the intensity of antigen m odulation were not predictive of the amount of MAb detected in the cyt oplasm.