Immunization with the Light Chain and the VL Domain of the Isologous Myeloma Protein 315 Inhibits Growth of Mouse Plasmacytoma MOPC315

Abstract
Prior immunization of BALB/c mice with free L chains from myeloma protein 315 (L315) and its variable domain (VL315) inhibited growth of s.c. injected MOPC315 tumor cells. Growth suppression observed after immunization with L315 was equivalent to that which resulted from immunization with the complete M315. VL315 and non-polymerized L315 did not elicit specific antibodies. Polymerized L315 induced suppression of MOPC315 growth and antibodies specific for free L315; these antibodies did not react with the complete M315, nor were they absorbed by MOPC315 tumor cells. Suppression of tumor growth was mediated by specifically sensitized cells acting in the absence of antibodies against M315 or L315. Immunization with the variable domain of the H chain from M315 (VH315) had no effect on growth of MOPC315. The M315 fragments and subunits that induced growth suppression were identical with those capable of inducing T [thymus-derived] helper cells in BALB/c mice.