T-cell immune response
One month after the second dose, CD4+ T cells in 33.3% (n=6/17) of patients responded to the S-RBD antigen in a short ex vivostimulation and cytokine-production assays (Fig 3). Four patients were excluded due to low cell viability and/or unresponsiveness to CD3 stimulation. Among the HCs, 73% (n=8/11) responded (one was excluded); however, the proportion of responders and percentage of responding CD4+ T cells did not significantly differ. Fifty percent (3/6) of patients with CVID with T-cell immune responses also responded with specific antibody production.
Thereafter, we investigated the CD4+ T-cell response’s persistence in 11 patients 6 months post-vaccination. The remaining patients were excluded due to loss to follow-up (n=3), or RT-PCR confirmed SARS-CoV-2 infection (n=3). Despite antibody-level decline, we observed a response in 50% (6/12) of patients, similar to that observed in month 1 (Fig 3). T cells, along with a humoral immune response, were observed in 5 of these patients (62.5%). The proportion of responders among the HCs remained constant (60%, n=9/15).