Effect of p110δ and p110γ deletion on extrathymic T cells. (A) Cell counts and flow cytomtery analysis of surface expression of TCRB were performed on whole blood and isolated PBMCs, respectively, whereas CD4 and CD8 expression was evaluated on total cells harvested from peripheral lymph nodes (B) and spleens (C) of WT control and p110γδ^-/-. Histologic examination of hematoxylin and eosin-stained lymph node (B) and splenic (C) sections (objective magnifications each 4 ×). Delineation of the T-cell population by immunoperoxidase detection of CD3⁺ counterstained with Meyer hematoxylin was also performed (100 ×; scale bar, 100 μm). Ca²⁺ flux in CD4⁺-gated T cells from WT control (D-E), p110γ^-/- (E), p110δ^-/- (E), and p110γδ^-/- (D-E) mice in response to TCR cross-linking. Values depicted represent the mean ± SE for 3 independent experiments performed in duplicate or triplicate. ^*Statistical significance compared with WT control (P < .05).