DEFECTIVE INTERLEUKIN-2 AND INTERFERON-GAMMA GENE-EXPRESSION IN RESPONSE TO ANTIGEN IN A SUBGROUP OF PATIENTS WITH COMMON VARIABLE IMMUNODEFICIENCY

Patients with common variable immunodeficiency (CVID) are heterogeneous in the clinical manifestations of the disease and in the underlying mechanisms leading to the immunodeficiency The impairment of B-cell function can be due to an intrinsic defect of the B cells, a deficiency in the function of the antigen-presenting cell, or a dysfunction in the course of T-cell activation. In the present report we have focused our attention on T-lymphocyte activation in three patients with CVID. Numbers of T and B cells, as well as CD4 and CD8 T cell subsets, were within the normal range. The patients' B cells secreted IgM but did not secrete IgG and IgA in response to B-cell stimuli in vitro. Addition of allogeneic T cells was followed by an increase in IgM production but had no effect on the other immunoglobulin isotypes. Examination of T-cell function revealed impaired proliferative response, interleukin-2 (IL-2) and interferon-gamma gene expression and IL-2 release after antigenic stimulation, whereas T-cell proliferation, as well as IL-2 gene expression and release in response to stimulation Wa anti-CD3, were comparable to those of healthy control subjects. Anti-CD3-induced IFN-gamma gene activation in T cells from two patients was comparable to that of control subjects, whereas T cells from the third patient showed reduced expression of IFN-gamma mRNA. In contrast to the decreased IL-2 and IFN-gamma mRNA levels, IL-2R transcripts examined in parallel were normal in CVID T cells on stimulation with antigen. The defect in IL-2 and IFN-gamma mRNA expression after stimulation with antigen, but not with anti-CD3, suggests an abnormality confined to T-cell activation by the T-cell receptor.