ANALYSIS OF THE T-CELL RECEPTOR IN THE LYMPHOPROLIFERATIVE DISEASE OFGRANULAR LYMPHOCYTES - SUPERANTIGEN ACTIVATION OF CLONAL CD3(+) GRANULAR LYMPHOCYTES

To investigate whether cell populations in CD3(+) lymphoproliferative disease of granular lymphocytes (LDGLs) were skewed toward the use of specific V beta regions, we studied the repertoire of T-cell receptor (TCR) V beta gene products in 18 patients, as well as their relationsh ip to the clonal bands in the Southern blot and the activation mediate d by superantigens, Using a panel of monoclonal antibodies (mAbs) for conserved V beta segments and PCR, a dominant population expressing a specific V beta region was demonstrated in all patients. In five (27%) cases, granular lymphocytes (GLs) were found to express the V beta 13 .1, while V beta 8 and V beta 6 were each expressed in three (17%) cas es. The remaining cases were characterized by the proliferation of TCR V beta 2, V beta 3, V beta 4, V beta 9, V beta 12, V beta 16, and V b eta 20. This finding indicates a biased usage of a limited TCR V beta in LDGLs, since nearly 60% of the cases utilized only three families o f the TCR V beta genes. In all of the cases studied, we proved that th e subset recognized by mAb and PCR was identical to that accounting fo r the extra band(s) of the Southern blot. This finding confirms the cl onal nature of the population identified according to TCR V beta expre ssion both by phenotype and PCR. On functional grounds, we evaluated w hether GLs can be activated through the specific TCR using the superan tigens recognizing discrete V beta families, such as staphylococcal pr oteins, including SEA, SEE, SEC1, SEC2, SED, and SEE. We demonstrated that the TCR-alpha/beta of clonal GLs in LDGL patients is functionally active in delivering cytotoxic and proliferative signals upon superan tigen activation.