Cellular immunity in rats with primary brain tumors: inhibition of macrophage migration by soluble extracts of avian sarcoma virus-induced tumors

Generation of cellular immune responses against a glioma-associated antigen(s)

The study demonstrated that RT2, a highly malignant anaplastic glioma, expresses antigens that make it susceptible to in vivo adoptive immunotherapy with cytotoxic T lymphocyte-containing immune cell populations. Rats were immunized with irradiated RT2 tumor cells and the adjuvant C. parvum. Lymphocytes from immunized rats were restimulated in vitro with irradiated RT2 tumor cells plus interleukin-2 (IL-2). The cells that proliferated and differentiated in vitro effectively killed RT2, but only low levels of cytotoxicity were observed against other histopathologically related and unrelated, syngeneic and allogeneic target cells. Adoptive transfer of immune cells combined with a 5-day course of systemic IL-2 produced specific regression of brain tumors growing as lung microfoci.

Glioma-associated antigens defined by monoclonal antibodies against an avian sarcoma virus-induced rat astrocytoma

S69-c15 is a highly immunogenic cell line derived from an avian sarcoma virus (ASV)-induced astrocytoma in F-344 rats. Monoclonal antibody (Mab) production was attempted by fusing F-344 rat splenocytes and mouse P3 X 63/Ag8.653 myeloma cells after a syngeneic immunization protocol. 336 fusion clones were screened by cell surface radioimmunoassay (CS-RIA) against the immunizing line S69-c15, rat kidney fibroblast line S203-c11 and Walker rat carcinoma line. Mabs 7G4, 9F1, 10E3 and 10E7 which reacted only with S69-c15 were chosen. Further analysis demonstrated that these Mabs reacted only with rat (13/23 astrocytomas, 2/4 gliomas, 1/11 neurinomas) or mouse (2/10 astrocytomas) neurogenic tumor cells induced by both viral and chemical agents. Reciprocal competition assays suggested that 7G4, 9F1 and 10E3 recognized the same epitope and that 10E7 reacted with a spatially close determinant. Antigen activity could not be found in adult rat tissues (brain, heart, lung, liver, kidney, spleen, thymus, intestine, muscle and peripheral nerve) and fetal brain (8, 12, 20 days gestation) by either absorption analysis or tissue staining. Preliminary characterization indicated that the epitope may be polypeptide-associated. Further antigen purification and tumor localization can be attempted with these Mabs.

Experimental allergic encephalomyelitis in Lewis rats bearing avian sarcoma virus-induced brain tumors

Lewis rats bearing avian sarcoma virus (ASV)-induced brain tumors were injected with guinea pig spinal cord emulsion and complete Freund's Adjuvant to determine if they remained susceptible to induction of experimental allergic encephalomyelitis (EAE). The incidence of EAE among rats with small, and moderate sized gliomas was similar to non-tumor-bearing controls (P less than 0.5; P less than 0.9) while 18 of 24 (75%) animals with large gliomas developed EAE as compared to 31 of 33 (93%) controls (P less than 0.05). The histologic features and geographical distribution of "ordinary' EAE were seen in controls and were maintained in tumor-bearing rats. The presence of an intracranial tumor did not significantly alter the ability of Lewis rats to develop EAE.