INDUCTION OF ANTIIDIOTYPIC HUMORAL AND CELLULAR IMMUNE-RESPONSES BY AMURINE MONOCLONAL-ANTIBODY RECOGNIZING THE OVARIAN-CARCINOMA ANTIGEN CA125 ENCAPSULATED IN BIODEGRADABLE MICROSPHERES

The use of biodegradable poly(DL-lactic-co-glycolic acid) microspheres as a cancer vaccine delivery system for induction of anti-idiotypic r esponses was investigated using a murine monoclonal antibody B43.13 th at recognizes the human ovarian cancer antigen CA125. Immunization of mice with mAb B43.13 encapsulated in poly(DL-lactic-co-glycolic acid) microspheres resulted in enhanced humoral and cellular immune response s compared with mAb B43.13 alone or mAb B43.13 mixed with microspheres . The antibody responses could be further enhanced by the co-encapsula tion of mAb B43.13 with monophosphoryl lipid A, a non-toxic adjuvant, in microspheres. Anti-idiotypic humoral responses were shown to result in Ab2 antibodies mimicking the nominal antigen CA125 and Ab3 antibod ies recognizing CA125. Further, microsphere delivery of mAb B43.13 als o resulted in induction of T cell responses involving T2 cells reactiv e with mAb B43.13 epitopes and T3 cells recognizing CA125. These resul ts indicate that microsphere delivery of Abl can induce both humoral a nd cellular anti-idiotypic responses relevant to cancer antigens. This raises the possibility of the use of such formulations for anti-idiot ypic induction immunotherapy for cancer.