NAIVE IDIOTYPE-SPECIFIC CD4-CELLS AND IMMUNOSURVEILLANCE OF B-CELL TUMORS( T)

The immunosurveillance hypothesis suggests that lymphocytes can recogn ize tumor-specific antigens expressed by transformed cells and initiat e their elimination. Immunosurveillance implies that lymphocytes of na ive phenotype can home to a tumor site and become activated by tumor-s pecific antigens. In this study, we have employed T-cell receptor tran sgenic mice as a source of naive, tumor-specific T cells. The transgen ic, CD4(+) T cells recognize a 91- to 101-residue fragment of the lamb da 2(315) immunoglobulin light chain presented by I-E(d) class II mole cules. Such naive, idiotype-specific, CD4(+) T cells protected against tumor development of a class II negative plasmacytoma (MOPC315) and a class II positive B lymphoma (F9), which both secrete lambda 2(315) i mmunoglobulin. Adoptive transfer experiments demonstrated that 2 x 10( 6) lymph node cells were sufficient for protection against MOPC315. De pletion of T-cell subsets indicated that transgenic CD4(+) cells were indispensable for tumor resistance. However, an additional role of CD8 (+) T cells is not ruled out. In contrast to the resistance against th e secreting MOPC315 and F9 cells, transgenic mice were not protected a gainst B lymphoma cells (F67), which do not secrete lambda 2(315) but express a truncated lambda 2(315) chain intracellularly. The results s uggest that lambda 2(315) is processed and presented by host antigen-p resenting cells, which in turn activate naive, idiotype-specific T cel ls.