UNEXPECTED PHENOTYPES AND PREDOMINANT TCR-V GENE USAGE IN RANDOM SELECTED SUBJECTS

The presence of a subset of T lymphocytes with an irregular phenotype has been identified in the peripheral blood of 22 subjects, selected among more than 5000 individuals evaluated for peripheral blood lymphocyte subset distribution as part of a routine procedure. By Southern Blot Analysis 13 out of 14 of the analysed samples presented additional non-germline bands, indicative of monoclonal or oligoclonal T cell expansions. Moreover, the cytometric analysis showed that 7 out of 19 analysed samples were restricted for a subfamily of the TCR variable regions. Thus, lymphocyte subsets with phenotypic irregularities could represent the clonally driven expansion of otherwise normally subpopulations, which may be present in peripheral blood below the limit of detection of routine phenotypic analyses. Such clonal populations could exert a regulatory activity either on the pathogenetic mechanisms of the disease or in maintaining homeostasis in healthy people.