EFFECTS OF SUPERANTIGENIC STIMULATION ON THE CORD-BLOOD ALPHA-BETA-T-CELL REPERTOIRE

Umbilical cord blood (CB) constitutes a promising alternative to bone marrow for allogeneic transplantation and is most remarkable for the r educed severity of GVHD compared with bone marrow, We have shown that although naive the TCR beta-chain repertoire appears fully constituted at birth in terms of mean size of the complementarity-determining reg ion 3 (CDR3) and of the usage of V and J gene segments, Its ability to respond to exogenous stimuli was tested with staphylococcal superanti gens TSST-1 and SEA (toxin at 1 ng/ml for 4 days), The amount of TCR t ranscripts was quantified and the percentage of representation of each BV family was calculated, TSST-1 induced BV2 expansion in both adult and CB samples, SEA activation gave a more variable pattern among indi viduals (adults n = 6; CB n = 6), BV6, BV18, BV22 and BV24 mere the mo st frequently expanded families, We did not observe notable difference s in either the modification of the TCRBV repertoire or the kinetics o f the response to SEA superantigen between adults and newborns. These data suggest that although naive, CB lymphocytes are as equally capabl e as adult lymphocytes of responding to superantigen stimulation.