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Regulation of expression of T cell γ chain, L3T4 and Ly‐2 messages in Abelson/moloney virus‐transformed T cell lines

Recent results have suggested that T cells may exist in two distinct pathways, one expressing α and β chain of the T cell receptor genes with either or both of the cell surface markers CD4 and CD8, while the other is negative for these cell surface markers and expresses the T cell‐specific γ chain genes. The relationship between these two pathways is not known. In this study, we have examined a series of either Abelson virus or Moloney virus‐derived T cell lines for their expression of these T cell receptor and cell surface marker genes. Results indicate that the Abelson T cell lines do not express the cell surface markers CD4 and CD8, but express relatively high levels of y chain transcripts. After culture of these cell lines with the phorbol ester phorbol myristate acetate and interleukin 2, a down‐regulation of these γ chain transcripts can be observed. More interestingly, we found that the Moloney virus‐derived T cell lines, which express the cell surface markers CD4 andiCD8, contain high levels of α and β chain T cell receptor transcripts but little or no γ transcripts even though they have rearranged these latter genes. The γ transcripts, however. can be induced to high levels after culture with phorbol myristate acetate and interleukin 2. In the process, the cell surface markers CD4 and CD8 and their transcripts were dramatically down‐regulated resulting in cells with high levels of γ chain transcripts and a CD4‐CD8‐ phenotype. The regulation of expression of these genes is reversible. Taken together, these results indicate that the T cell receptor γ chain genes and those of the cell surface markers CD4 CD8 can be regulated in vitro by external factors and it opens up the possibility of studying the regulatory sequences associated with these genes.