Study of the B cell memory compartment in common variable immunodeficiency

We evaluated the B cell memory pool among blood B cells from 20 patients wi th common variable immunodeficiency (CVID). CD27(+) B cell number was norma l or increased in 6 patients (with 95 % CD27(+) B cells in 1 patient) and d ecreased in 14 patients. In 13 or 15 patients studied, the CD27 molecule wa s detectable on less than 50 % IgG or IgA B cells, indicating a defect in t he maturation of these memory cells. Within the group of patients with a lo w number of CD27(+) B cells, no up-regulation of this molecule was observed after in vitro stimulation of purified B cells from 3 of 5 patients studie d, suggesting an intrinsic B cell defect. In addition, ligation of the CD27 molecule was unable to trigger terminal differentiation of purified B cell s in 1 of 2 cases with a large number of CD27(+) B cells. Finally, the CD27 ligand was normally expressed on activated T cells in only 5 of 14 patient s studied. These data confirm the heterogeneity of immunological defects in patients with CVID. Abnormal expression and/or function of the CD27-CD70 m embers of the TNF/TNF receptor family contribute to the immunological defec t.