Continuing V γ2 to J γ2 rearrangements of murine T cell receptor gamma genes in a B-committed immature cell line

Abstract

In SPL2-1-2, a murine B-committed immature cell line transformed with a temperature-sensitive mutant of Abelson virus, T cell receptor (TCR) γ gene rearrangements, together with IgH gene rearrangements, were induced during culture at a non-permissive temperature (39°C). During 11–12 months of culture, TCRγ gene rearrangements occurred in all cells. In contrast to TCR γ genes, neither TCR β or TCR δ were detected even after 11–12 months of culture at a non-permissive temperature. The majority of the TCR γ gene rearrangements observed here were V γ 2 to J γ 2 joinings and the remaining rearrangements were J γ 1-linked. V γ 1 to J γ 4 and V γ 3 to Jγ 3 joinings detected. Approximately 70% of cells with TCR γ gene rearrangements produced normal-sized transcripts from the rearranged TCR γ 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 γ genes and that Vγ 2 to Jγ 2 joinings occurred preferentially in this B-committed immature cell line. Furthermore, TCR γ gene rearrangements also occurred in intracytoplasmic μ -chain producing cells. This indicated that the existence of intracytoplasmic μ-chains did not prevent TCR γ gene rearrangements, although the existence of μ-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.