Continuing V gamma 2 to J gamma 2 rearrangements of murine T cell receptor gamma genes in a B-committed immature cell line.

In SPL2-1-2, a murine B-committed immature cell line transformed with a temperature-sensitive mutant of Abelson virus, T cell receptor (TCR) gamma gene rearrangements, together with IgH gene rearrangements, were induced during culture at a non-permissive temperature (39 degrees C). During 11-12 months of culture, TCR gamma gene rearrangements occurred in all cells. In contrast to TCR gamma genes, neither TCR beta or TCR delta were detected even after 11-12 months of culture at a non-permissive temperature. The majority of the TCR gamma gene rearrangements observed here were V gamma 2 to J gamma 2 joinings and the remaining rearrangements were J gamma 1-linked. V gamma 1 to J gamma 4 and V gamma 3 to J gamma 3 joinings were not detected. Approximately 70% of cells with TCR gamma gene rearrangements produced normal-sized transcripts from the rearranged TCR gamma genes. Cloning and sequencing analysis of a cDNA from the transcripts demonstrated that the whole structure of the cDNA was similar to that of T-lineage cells. These results showed that TCR gene rearrangements were restricted to the gamma genes and that V gamma 2 to J gamma 2 joinings occurred preferentially in this B-committed immature cell line. Furthermore, TCR gamma gene rearrangements also occurred in intracytoplasmic mu-chain producing cells. This indicated that the existence of intracytoplasmic mu-chains did not prevent TCR gamma gene rearrangements, although the existence of mu-chains is known to inhibit further productive IgH gene rearrangements, (allelic exclusion). These results should provide many implications for the mechanism of TCR gene rearrangements, especially that of cross-lineage rearrangements.