Antibody response to COVID-19 vaccine has been shown to be diminished in rituximab (RTX)-treated patients. We compared humoral and T-cell responses in healthy controls (HC) and patients with autoimmune diseases (AID) treated with RTX or other immunosuppressants (other IS) vaccinated with two doses of mRNA COVID-19 vaccine.
We performed anti-spike IgG and neutralization assays just before and 28 days after the second BNT162b2 vaccination. The specific T-cell response was assessed in activated CD4 and CD8 T-cells using intracellular flow-cytometry staining of cytokines (IFNγ, TNF and IL-2) after stimulation with SARS-CoV-2 spike peptide pools.
A lower proportion of responders with neutralizing antibodies to vaccine were observed in the RTX group (29% n=24) compared to the other IS (80% n=35) and HC (92% n=26) groups. No patient treated by RTX in the last 6 months responded. Time since last infusion was the main factor influencing humoral response in RTX-treated patients. The functional CD4 and CD8 cellular response to SARS-CoV-2 peptides for every single cytokine or polyfunctionality were not different in the RTX group compared to other IS groups and HC. In RTX-treated patients, the T-cell response was not different in patients with and without a humoral response.
RTX induced diminished antibody response to mRNA COVD-19 vaccine, but the functional T-cell response was not altered compared to HC and AID patients treated with other IS. Further work is needed to assess the clinical protection granted by a functionally active T-cell response in the absence of an anti-spike antibody response.