CLONAL PREDOMINANCE, BUT PRESERVATION OF A POLYCLONAL RESERVOIR, IN THE NORMAL ALPHA-BETA-T-CELL REPERTOIRE

We recently demonstrated that the peripheral gamma delta T-cell repert oire becomes oligoclonal with increasing age. Although this junctional homogeneity should not severely affect the ability of gamma delta T c ells to respond to foreign antigens, we reasoned that a similar oligoc lonal repertoire of alpha beta T cells would lead to a profound impair ment of the MHC-restricted response. We used heteroduplex analysis in this research to study the clonal complexity of the peripheral alpha b eta T-cell repertoire in human subjects and supply evidence for the pr esence of alpha beta clonal expansions. Clonal predominance in the alp ha beta T-cell repertoire of normal subjects was not simply related to age, since the PBL of young donors also showed clonal expansions and did not always correlate with a numeric increase in the corresponding V beta family. However, the type of alpha beta expansion appears to be strikingly different from the gamma delta expansions. In the case of alpha beta T cells, even in the presence of clonal dominance, evidence for a residual polyclonal background was found in all the donors test ed, irrespective of age. The observation that true oligoclonality is e xceptionally rare among alpha beta T lymphocytes could mean that maint enance of a highly diversified reservoir of TCR is primary for these c ells throughout life. (C) American Society for Histocompatibility and Immunogenetics, 1997.