Phenotypic dissection of cord blood immunoregulatory T-cell subsets by using a two-color immunofluorescence study.

Expression of TQ1(Leu8) and 2H4 antigens on human cord blood T-cell subsets was evaluated by a double immunofluorescence analysis. In normal adult blood all of the helper function for B-cell differentiation is confined to the smaller OKT4+TQ1-(Leu8-) cell subset, while the OKT4+TQ1+(Leu8+) cell subpopulation includes a subset of suppressor inducer 2H4+(JRA+) cells. Our results indicated that the OKT4+TQ1-(Leu8-) cell subpopulation was decreased and the reciprocal OKT4+TQ1+(Leu8+) cell subset was markedly increased in cord blood E-rosetting OKT3+ cell population. A rise in the number of cord OKT4+2H4+ cells was also found. In addition, TQ1 antigen was present on OKT3+E-, a less mature, cord T-cell subset, not present in adult blood. These findings may not only be of help in understanding lymphoid cell development during ontogeny, but also may agree with the reported strong-suppressor and weak-helper activities exerted by the T-cell subsets circulating in human cord blood.