Distribution and phenotypes of duodenal intraepithelial gamma/delta T cells in patients with various types of primary B-cell deficiency.

Expression of the gamma/delta T-cell receptor (TCR) on CD3+ intraepithelial lymphocytes (IEL) was studied in situ by two-color immunofluorescence on duodenal tissue sections from 34 infection-prone, adult patients with various types of primary hypogammaglobulinemia, classical Bruton's, Bruton-like or congenital, and common variable immunodeficiency. TCR gamma/delta+ IEL proportions (median 4.3%, range 0.3-43.3%) were within the range (0.3-38.3%) for histologically normal controls (n = 11), and there was no significant difference between the three patient categories. The total number of CD3+ IEL (mostly CD8+) per intestinal length unit was significantly higher (P < 0.004) in patients than in controls. In addition, TCR gamma/delta+ IEL per length unit, as well as TCR gamma/delta+ IEL proportions, were significantly increased (P < 0.008 and P < 0.05) in 14 patients with intestinal villous atrophy. Paired staining revealed that most (approximately 94%) TCR gamma/delta+ IEL in B-cell deficiency were CD8-, and a large fraction (approximately 67%) expressed the V delta 1/J delta 1-encoded epitope. No relationship was found between CD3+ or TCR gamma/delta+ IEL and the number of CD3+, CD4+, CD8+, and B lymphocytes or the CD4:CD8 ratio in peripheral blood. TCR gamma/delta+ IEL thus appeared to maintain a normal distribution in B-cell deficiency, except for being increased in patients with villous atrophy. Enhanced T-cell-mediated immunity, as possibly reflected by the numerical increase of CD3+ IEL, might compensate for a deficient mucosal B-cell system.