Neonatal T4⁺ lymphocytes: Analysis of the expression of 4B4 and 2H4 antigens

Using monoclonal antibodies anti-2H4 and anti-4B4 we investigated by double immunofluorescence and immunorosette technique the presence of cells displaying the helper-inducer and the inducer of suppression phenotype among T4⁺ cord blood cells. The analysis of the estimated frequencies of subpopulations of T4⁺ cells shows that a high percentage of T4⁺ cord blood cells can coexpress both antigens in comparison to adult. Furthermore the percentage of T4⁺ cells with helper-inducer phenotype (2H4^-4B4⁺) is significantly lower than that in the adult, while the percentage of T4⁺ cells with suppressor-inducer phenotype (2H4⁺4B4^-) although higher, is not significantly different. These findings suggest that the relative immunoincompetence observed in the newborn may result from a variety of mechanisms including a low percentage of helper-inducer (4B4⁺2H4^-) T4⁺ lymphocytes possibly also associated to an increased number of suppressor-inducer T4⁺ cells (2H4⁺4B4^-).