Elevated plasma levels and aberrant response to IL-7 in CVID. (A) Individual levels of plasma IL-7 (pg/mL) in 72 CVID patients (○) and 23 healthy controls (•). Horizontal lines indicate median values (median (25%-75%) for CVID, 4.9 pg/mL [3.05-7.65 pg/mL] and for controls, 3.0 pg/mL [2.15-4.85 pg/mL]). (B) The absent correlation between plasma IL-7 and numbers of circulating T cells in CVID patients (n = 72). (C) The effects of IL-7 (10 ng/mL) on in vitro proliferation in suboptimally stimulated (anti-CD3 [10 ng/mL]) T cells from CVID patients with normal plasma levels of IL-7 (n = 10; ○), CVID patients with high plasma levels of IL-7 (ie, > 10 pg/mL, n = 6;), and healthy controls (n = 13; •). The y-axis shows scintillation counts per minute (cpm; see “Study design”). (D) The effects of IL-7 (10 ng/mL) on in vitro secretion of IFNγ in suboptimally stimulated (anti-CD3 [10 ng/mL]) T cells from CVID patients with normal (n = 8) or elevated (ie, > 10 pg/mL; n = 7) plasma levels of IL-7 and healthy controls (n = 11); symbols as in panel C. n.s. indicates not significant. (E) Secreted levels of TGFβ1 in T cells from CVID patients (n = 13) stimulated with anti-CD3 [40 ng/mL], anti-CD28 [50 ng/mL], and IL-7 [10 ng/mL] related to plasma levels of IL-7. Note the positive correlation in patients with normal pl.IL-7 (r = 0.96; P = .003) and the absent correlation in patients with high pl.IL-7 (indicated by dotted lines).