RESPONSE OF A MURINE EPIDERMAL V-GAMMA-1 V-DELTA-6-TCR(+) HYBRIDOMA TO HEAT-SHOCK PROTEIN HSP-60/

In the epidermis, the major population of T lymphocytes expresses a T- cell receptor (TCR) with V gamma 5 and V delta 1 variable regions, whi ch is unique to this tissue. Roberts ef al and Ezquerra et al, also de scribe a minor population of gamma delta-TCR+ cells in the epidermis t hat expresses a V gamma 1/V delta 6 TCR. These cells are different fro m other epidermal T cells in that they ''spontaneously'' produce cytok ines, a result thought to be due to autoreactivity. Over the past 5 ye ars, our laboratory has produced V gamma 1/V delta 6(+) T-cell hybrido mas from many tissue sources. These spontaneously produce cytokines bu t also are activated by heat shock protein (HSP-60)-derived peptides. Ezquerra et al report that none of their V gamma 1/V delta 6(+) epider mal T-cell lines derived from C3H/HeN mice respond to HSP-60. Of the 9 9 gamma delta-TCR(+) hybridomas we have produced from epidermal T cell s of C57BL/6 mice, only one expressed the V gamma 1/V delta 6 TCR. Thi s hybridoma, 703BET-2.12, not only spontaneously produces cytokines, b ut, unlike the V gamma 1/V delta 6-TCR(+) epidermal T cells of Ezquerr a et al, it also responds to the whole HSP-60 protein and a 17-mer HSP -60 peptide from M. leprae, producing increased levels of interleukin- 2 of up to approximately ten-fold above the spontaneous level. This sh ows that V gamma 1/V delta 6-TCR(+) epidermal T cells can respond to H SP-60. To confirm that 70BET-2.12 expresses TCR genes similar to those of cells that have HSP-60 reactivity, V<gamma1-C gamma 4 and V delta 6-C delta cDNA were produced from RNA isolated from this hybridoma, am plified by the polymerase chain reaction, and sequenced. The gamma and delta TCR gene sequences were similar but not identical to previously published sequences of HSP-60-reactive cells from lymphoid and other organs. No explanation can be found for the discrepancy between our fi ndings and those of others at the level of TCR expression such that ot her strain-specific factors might be responsible for HSP-60 reactivity .