Immune Response in Strain 2 Guinea Pigs to the Syngeneic L2C Leukemia

Abstract

The L2C leukemia is a transplantable acute B lymphoblastic leukemia that arose spontaneously in a female strain 2 guinea pig (1). The presence of immunoglobulin (Ig) and complement receptors on the surface of L2C tumor cells has established the B lymphocyte lineage of this leukemia (2). Five closely related mutant sublines of the L2C leukemia have been described (3) and are presumed to be derived from the same stem cell on the basis of cytogeneic analyses (4). The sublines share a common IgM idiotypic (id) determinant(s) and can be classified into two major groups, those that have detectable immune-associated antigens (Ia) on their cell surface and those that lack detectable Ia antigens on the basis of serological analysis (3). The presence of Ia antigens is apparently important in eliciting immunity against the tumor because effective L2C tumor protection is induced in normal strain 2 guinea pigs when immunized with Ia⁺ L2C tumor cells in adjuvant, but not generally with Ia^- L2C tumor cells (3). However, immunization with Ia⁺ L2C cells protects the strain 2 guinea pigs against any of the 5 sublines. The latter finding supports the early observations made by Gross (5) that some strain 2 guinea pigs, when given a small dose of viable L2C tumor cells, developed resistance to a secondary challenge of L2C inoculum that produced fatal disease in syngeneic animals not previously given L2C tumorcells. Taken together, these results indicate that a tumor-associated transplantation antigen(s) (TATA) is present on L2C lymphoblasts. The IgM id determinants on the L2C cell surface have been implicated as a TATA for this tumor (6).