Expression of C gamma 4 T cell receptors and lack of isotype exclusion by dendritic epidermal T cell lines

Although four murine C gamma gene segments (C gamma 1, 2, 3, and 4) are known to exist, the large majority of expressed gamma-chains have been shown to be of the C gamma 1 isotype and no evidence exists for the expression of more than one receptor by gamma delta TCR-bearing cells. We investigated the nature of the TCR expressed on a number of murine dendritic epidermal T cell-derived cell lines by using both Northern blot and immunoprecipitation analyses. One of these CD3+ cell lines (T195) expresses C gamma 4, V gamma 1, and delta mRNA, and its CD3-associated TCR complex can be precipitated by both anti-C gamma 4 and anti-delta sera, indicating that this receptor is a C gamma 4/delta heterodimer. Furthermore, we show that two cell lines (Y245, Y93) express two distinct TCR gamma-chains, one derived from the C gamma 4 locus, whereas the second gamma-chain is probably derived from the C gamma 2 locus. Together with the previous demonstration of C gamma 1/delta TCR on a number of dendritic epidermal T cell lines (DETC), these results indicate that such DETC are capable of expressing a variety of gamma delta TCR and that, in some DETC, isotype exclusion of gamma-chain expression does not occur.