IFNG and agammaglobulinemia: However, other patients of our cohort without detectable specific IgG+ RBD+ MBCs, including 1 with X-linked agammaglobulinemia deficiency, 2 with CVID, and a patient with profound hypogammaglobulinemia after rituximab treatment, also presented impaired antibody production but positive T-cell response by using a ELISpot estimating IL-2 and IFNγ secretion (27, 33), as previously reported.