To aid the understanding of tumor cell lysis by cytotoxic T lymphocytes (CTLs), studies will be carried out on a model system in which CTLs are specific for a glycoprotein (G) of vesicular stomatitis virus (VSV). The susceptibility of various VSV-infected targets to lysis will be correlated with the extent to which G and H-2 molecules are associated on the target cell surface. Covalently joined H-2 and G molecules, prepared by a crosslinking reagent, will also be tested for their ability to stimulate the development of CTLs. In a second line of study variability of lambda light chains of the mouse will be analyzed. Chains of the lambda 2 type will be sequenced especially in the 3rd hypervariable and 4th framework (J) region. Chains of the lambda 3 type will be sequenced to determine whether they share V and J genes with lambda 2, or whether they are encoded by their own unique V lambda 3 and J lambda 3 genes.