Adjuvant Effect of Liposome Presentation of Soluble Tumour Associated Antigen

Abstract

Lack of immunogenicity of cell surface antigen when dissociated from cell membranes has centred on the use of liposomes since they can mimic cell surface presentation (Curman et al., 1978, Enghelhard et al., 1978). Moreover, liposomes have been shown to act as an adjuvant (Kinsky and Nicolotti, 1977) and strong enhancement of the antibody response has been described for protein antigens such as diphtheria toxin (Allison and Gregoriadis, 1974), hepatitis B surface antigen (Gregoriadis and Manesis, 1980), and serum albumins or gamma-globulins (Heath et al., 1976, Van Rooijen and Van Nieuwmegen, 1977-1979). Therefore incorporation of tumour cell surface antigen into liposomes could prove to be of utmost interest. We have developed the association with liposomes of Gross Cell Surface Antigen (GCSAa) (Gerlier et al., 1978), a major cell surface antigen of protein nature, (Ledbetter and Nowinski, 1977, Snyder et al., 1977), associated with Gross virus induced lymphomas in mouse (Old et al., 1965) and rat (Geering et al., 1966). Immunogenicity of GCSAa sensitized liposomes has been studied in syngeneic animals (Gerlier et al., 1980a, b). GCSAa appears to play an important role in host tumour relationship and can induce high antibody response in syngeneic rats (Gerlier et al., 1977). Immunochemical characteristics of the association with liposome of GCSAa have been described previously (Sakai et al., 1980) and liposome presentation of this antigen has been shown to succeed in inducing cytotoxic antibodies to GCSAa reaching in some instances the level obtained following immunization with viable syngeneic tumour cells. Our present purpose is to further study the requirements for obtaining an adjuvant effect of liposome presentation in this tumour model.