Lack of specific antibody response in common variable immunodeficiency (CVID) associated with failure in production of antigen‐specific memory T cells

Several T cell defects have been described in the antibody deficiency disease, CVID, but there have been few data on the generation of responses of specific T cell populations to primary neoantigens. We have now used immunization with the neoantigens, keyhole limpet haemocyanin (KLH) and DNP‐Ficoll, to evaluate immune responses in CVID patients and normal donors. B and T cell responses were examined 2 and 4 weeks post‐immunization. Sera were examined for IgM and IgG anti‐KLH responses by ELISA and for anti‐DNP‐Ficoll activity by haemagglutination. The frequency of KLH‐responsive T cells was measured by DNA synthesis in a limiting dilution culture system. Low density cells enriched for dendritic cells were pulsed with KLH and cultured with different numbers of autologous T cells. T cells from normal donors and from patients showed a low frequency of antigen‐specific precursor T cells (≤1:200 000). After KLH immunization the frequency increased in normal donors (1:60 000 and 1:30 000 at 2 and 4 weeks, respectively), while in CVID patients it did not change from the pre‐immunization level. The defect may extend to a dysfunction of antigen‐specific cells, rather than being solely due to the reduced numbers of cells, since mean responses of ‘positive’ wells were also reduced. The serum‐specific antibody response paralleled the T cell data, in that all normal donors but none of the CVID patients generated IgG KLH‐specific antibodies. CVID patients did produce IgM antibodies against the T‐independent DNP‐Ficoll, but at a lower level than normal controls. These data show that both T and B cells from CVID patients have defective responses to specific antigen, implicating both lineages in the antibody deficiency.