Sequences related to immunoglobulin kappa chain messenger RNA in T cells.

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Abstract
Using molecular hybridization, an investigation was made to determine whether T [thymus-derived] cells contain RNA sequences homologous to RNA which codes for immunoglobulin .kappa.-chain. A radioactive probe of complementary DNA (cDNA) was prepared by transcription of purified .kappa.-chain mRNA from mouse myeloma MOPC-41 with reverse transcriptase (RNA-dependent-DNA nucleotidyltransferase) from avian myeloblastosis virus. The cDNA probably corresponded only to the constant region and 3''-terminus of .kappa.-chain mRNA. .kappa.-Chain cDNA hybridized efficiently with RNA from thymus cells and an established culture of thymoma cells. The thymus and thymoma cells contained 99.8% and 100% .theta.-positive cells, respectively. Quantitatively, the average thymus T cell contained about 1/2 as much .kappa.-chain mRNA as the average spleen B cell (bone-marrow dependent lymphocyte), whereas the thymoma cells contained only 1/33 as much. Control hybridizations of .kappa.-chain cDNA with myeloma and liver RNA support the conclusion that T cells in the thymus and in the thymoma cell line synthesize .kappa.-chain mRNA-like molecules. The thermal stability of hybrids of .kappa.-chains cDNA with RNA from spleen, thymus, thymoma and another .kappa.-chain producing myeloma tumor was lower than that with MOPC-41 RNA. This finding may be due to the existence of several slightly different c.kappa.-genes in the mouse as suggested by various control experiments.