DEVIATED OVEREXPRESSION OF TCR-BETA, TCR-GAMMA, CD4, AND CD8 ON THYMIC LYMPHOMAS INDUCED BY 1-PROPYL-1-NITROSOUREA - DESTRUCTION OF THE ALLELIC EXCLUSION OF TCR-BETA AND EXPRESSION OF FUNCTIONAL TCR-BETA-GAMMAHETERODIMER ON A LYMPHOMA, CFTL53

Thymic lymphomas (FTLs) induced by the chemical carcinogen 1-propyl-1- nitrosourea (PNU) in E344 rats showed deviated overexpression of TCR-b eta, TCR-gamma, CD4, and CD8. Even though most FTLs were in the CD4(+) CD8(+) stage, all FTLs expressed TCR-beta mRNA with TCR-gamma mRNA, bu t without TCR-alpha mRNA or TCR-delta mRNA, One of the FTLs, cFTL53, e xpressed two kinds of TCR-beta mRNA and two kinds of TCR-gamma mRNA, b ut did not express any mRNA of TCR-alpha or TCR-delta. Both alleles of TCR-beta loci were rearranged on cFTL53. cDNA cloning and sequencing analysis showed that one TCR-gamma mRNA, V gamma 4-J gamma 1-C gamma 1 , and both TCR-beta mRNA, V beta 2-D beta 2-J beta 2.1 and V beta 19-D beta 2-J beta 2.1-C beta 2, on cFTL53 were in the productive form, wh ile the other TCR-gamma mRNA, V gamma 1-J gamma 4-C gamma 4L, was not. Both TCR beta-chains and a TCR gamma-chain were expressed on cFTL53, making a novel set of TCR-beta gamma heterodimer. Cross-linking of TCR -beta gamma heterodimer on cFTL53 resulted in a calcium flux, indicati ng that TCR-beta gamma works as a signal transduction receptor. Thus, there are four strange phenomena on FTLs; CD4 and CD8 are expressed wi thout TCR-alpha beta or TCR-gamma delta, TCR-beta mRNA and TCR-gamma m RNA were expressed simultaneously without TCR-alpha and TCR-delta mRNA on FTLs, the allelic exclusion of TCR-beta was destroyed in cFTL53, a nd a novel set of functional TCR-beta gamma heterodimer was expressed on cFTL53.