Recovery of F-actin capping in T-CVID T cells by reconstitution of Vav1 expression. (A) Relative percentage of F-actin cap formation in response to CD3/CD28 costimulation in T cells from the 4 patients with T-CVID (expressed as percentage of capping in T cells from 4 matched healthy controls after transfection with empty vector), as measured by confocal microscopy of cells labeled with fluorochrome-conjugated phalloidin. T cells were cotransfected with a GFP reporter and either the empty vector or the same vector encoding myc-tagged Vav1. Capping was quantitated on GFP⁺ cells (n = 100). The error bars represent SD. (B) Two representative examples of F-actin labeling (tetramethylrhodamine isothiocyanate [TRITC]-phalloidin) and GFP fluorescence in Vav/GFP cotransfected T-CVID T cells activated for 1 hour by CD3/CD28 costimulation, together with the respective overlays, are shown. (C) An immunoblot analysis with anti-myc mAb of a representative control and T-CVID T-cell lysate transfected with the empty vector or the Vav expression vector is also shown. The arrow indicates the migration of myc-tagged VAV1.