IL-2 RECEPTOR-POSITIVE INTRATHYROIDAL LYMPHOCYTES IN GRAVES-DISEASE -ANALYSIS OF V-ALPHA TRANSCRIPT MICROHETEROGENEITY

There has been considerable interest recently in the possible restrict ion of the TCR repertoire in autoimmune disorders, because such restri ction would have important therapeutic implications. Reports of restri ction of the TCR Valpha but not Vbeta repertoire in the thyroid in Gra ves' disease could not be repeated in an earlier study. Using RNA deri ved from matched peripheral blood, thyroid tissue, intrathyroidal lymp hocytes (ITL), and IL-2R+ and IL-2R- subpopulations of ITL from Graves ' patients, we conducted reverse transcription polymerase chain reacti on/Southern blot analysis of TCR Valpha family usage. No evidence was found for Va restriction in the IL-2R+ subpopulation of ITL from eight patients, one of whom was operated on within 1 mo of diagnosis. We ha ve further analyzed samples from seven of these patients by resolution on denaturing polyacrylamide gels. Typically, a single dominant band was amplified with surrounding minor bands in a normal distribution. D ominant and minor species were both the result of amplification from i n frame Valpha transcripts, and the minor bands were separated in size by increments of 3 bp. We found no evidence for reduced heterogeneity of the Valpha transcripts in ITL or IL-2R+ ITL populations relative t o peripheral blood in the vast majority of samples. This therefore sug gests that there is little difference between the blood lymphocyte pop ulation and the activated T cell population in the thyroid in patients with Graves' disease, and indicates that in autoimmune thyroid diseas e, this method of analysis is not sufficient to distinguish between au toreactive and bystander T cell populations.