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 a mong more than 5000 individuals evaluated for peripheral blood lymphoc yte subset distribution as part of a routine procedure. By Southern Bl ot Analysis 13 out of 14 of the analysed samples presented additional non-germline bands, indicative of monoclonal or oligoclonal T cell exp ansions. Moreover, the cytometric analysis showed that 7 out of 19 ana lysed samples were restricted for a subfamily of the TCR variable regi ons. Thus, lymphocyte subsets with phenotypic irregularities could rep resent the clonally driven expansion of otherwise normally subpopulati ons, which may be present in peripheral blood below the limit of detec tion of routine phenotypic analyses. Such clonal populations could exe rt a regulatory activity either on the pathogenetic mechanisms of the disease or in maintaining homeostasis in healthy people.