Evaluation of naive phenotypes for TREC content.

(A) The 3 naive phenotypes (CD45RA⁺ CD45RO⁻, CD45RA⁺CD62L⁺, and CD45RO⁻CD27⁺ CD95^low) were isolated by sequential immunoselection, and the purity of the cultures is indicated in the upper right quadrant of the representative flow charts shown for CD45RA⁺CD45RO⁻ (panel Ai), CD45RA⁺CD62L⁺ (panel Aii), and CD45RO⁻CD27⁺CD95^low (panel Aiii). (B) TREC levels are equivalent in the CD4⁺ naive T-cell phenotypes. DNA from CD45RA⁺CD45RO⁻, CD45RA⁺ CD62L⁺, and CD45RO⁻CD27⁺CD95^low populations was isolated, and the level of coding joint TRECs was quantified by PCR-ELISA. P = .67, obtained by comparing TRECs from the 3 populations; this is shown in the figure, which was based on a mixed linear model. Data are based on 5 different donors. (C) Isolation of the CD45RA⁺CD45RO⁻ population enriches simultaneously for CD45RA⁺CD62L⁺ and CD45RO⁻CD27⁺CD95^low naive subsets. CD45RA⁺CD45RO⁻ T cells were isolated and evaluated by flow cytometry for the expression of CD62L, CD45RO, CD27, and CD95. The bar chart indicates that 97% of the CD45RA⁺CD45RO⁻ cells are also CD45RA⁺CD62L⁺ and 92% are CD45RO⁻CD27⁺CD95^low.