Expression of p85α, p55α, and p50α and the p110 isoforms in hematopoietic cells and cell lines from healthy controls, disease controls, and the patient. (A) Expression of the indicated proteins in peripheral blood T cells isolated by negative selection and in activated T cells that had been stimulated with phytohemagglutinin and then supplemented with 10% IL-2 every 2–3 d for 2 wk. (B) Expression of the same proteins in primary B cells, EBV-transformed B cell lines, and NK cells. Because both the patient (Pt) and the disease controls (DC) lack B cells, expression of PI3K isoforms from two healthy controls (HC) is shown to document that the absence of p50α and p55α was a reproducible finding. The patient had too few NK cells to permit analysis. (C) Expression of PI3K isoforms in neutrophils and DCs. The immunoblots in A–C were sequentially probed with antibodies to p110δ, p85α N terminus, p85α C terminus, and actin. (D) The expression of p110 isoforms in activated T cells and neutrophils is shown. The disease control for NK cell analysis had mutations in λ5. All other disease controls had mutations in BTK.