Comparative expression analysis of the intracellular μH chain, intracellular VpreB, or cell surface μH chain by BM B-lineage cells.

The analysis compared a 5-year-old healthy child and an XLA patient (P3). The intracellular staining of BM cells for VpreB and the μH chain in combination with CD19 was performed as described in the legend of Figure 1. For the intracellular versus cell surface expression of the μH chain by BM B-lineage cells, viable BM cells were first treated with a PE-labeled antihuman μH chain Ab, fixed, permeabilized, and subsequently stained with a PC5-labeled anti-CD19 mAb and FITC-antihuman μH chain Ab. The open square denotes mature B cells that showed more intense expression of the μH chain than the presumed pre–B-cell population.