Immune responses of mice to iodoacetate-treated Ehrlich ascites tumour cells

Autoimmunity induced by injection of virus-modified cell membrane antigens in syngeneic mice

C3H/Bi mice developed autoantibodies after repeated inoculations of isolated membranes from primary tissue cultures of a syngeneic ascites lymphoma in which Newcastle disease virus had grown. This was in addition to the tumor transplantation resistance and cytotoxic antibodies previously demonstrated. The complement-fixing antibodies were completely removed from sera by adsorption with ascites tumor cells but only partially by normal mouse liver powder or C3H/Bi erythrocytes. With continued immunization, antibodies to deoxynucleoprotein and heterophile reagins also appeared. After several months, mice showing these serological reactions died with a wasting disease characterized by loss of lymphoid tissue and scarred, atrophied kidneys. No significant antibody response or autoimmune disease occurred in mice receiving membranes from uninfected syngeneic ascites lymphoma.

Immunogenicity of a rat leukaemia of spontaneous origin (SAL)

The SAL rat leukaemia, which resembles acute myeloblastic leukaemia, appeared initially to be non-immunogenic since resistance to an i.p. challenge with as few as 100 cells could not be obtained using stimulation of the RES or by immunization with SAL cells exposed to x-rays, nitrogen mustard, iodoacetate or glutaraldehyde. However, immunization with SAL cells exposed to low doses of mitomycin-C slowed the growth of the challenge inoculum. Cells treated with high doses of mitomycin-C did not immunize. The results are interpreted in terms of rapid shedding of a tumour-specific antigen from the membrane of SAL cells.

The effect of antiserum fractions on Ehrlich ascites tumour cells

Hyperimmune heterologous serum produced in sheep against mouse Ehrlich ascites tumour cells was absorbed with normal mouse tissue and fractionated by DEAE column chromatography into IgG1 and IgG2 fractions. In vitro cytotoxicity test showed that sheep anti-Ehrlich ascites tumour IgGl fraction was cytotoxic to (51)Cr labelled tumour cells whereas IgG2 had no cytotoxic effect. Pretreatment of the tumour cells with the non-cytotoxic IgG2 fraction slightly inhibited the cytotoxic action of IgG1 in vitro.When EAT cells were coated with either IgG1 or IgG2 by preincubation in vitro before injecting intraperitoneally into mice, both fractions protected the animals against tumour growth. Injection of IgG2 and IgGl fractions separately, one before and the other after the injection of EAT cells, resulted in partial protection only. The difference encountered between the in vitro and in vivo findings could be attributed to the host defence mechanisms involved in the in vivo test system.