Abstract
Background:
The innate immune cytokine interleukin (IL)-1 can affect T cell immunity, a critical factor in host defense. In a previous study, we identified a subset of human CD4+ T cells which express IL-1 receptor 1 (IL-1R1). However, the expression of such receptor by viral antigen-specific CD4+ T cells and its biological implication remain largely unexplored. This led us to investigate the implication of IL-1R1 in the development of viral antigen-specific CD4+ T cell responses in humans, including healthy individuals and patients with primary antibody deficiency (PAD), and animals.
Methods:
We characterized CD4+ T cells specific for SARS-CoV-2 spike (S) protein, influenza virus, and cytomegalovirus utilizing multiplexed single cell RNA-seq, mass cytometry and flow cytometry followed by an animal study.
Findings:
In healthy individuals, CD4+ T cells specific for viral antigens, including S protein, highly expressed IL-1R1. IL-1β promoted interferon (IFN)-γ expression by S protein-stimulated CD4+ T cells, supporting the functional implication of IL-1R1. Following the 2nd dose of COVID-19 mRNA vaccines, S protein-specific CD4+ T cells with high levels of IL-1R1 increased, likely reflecting repetitive antigenic stimulation. The expression levels of IL-1R1 by such cells correlated with the development of serum anti-S protein IgG antibody. A similar finding of increased expression of IL-1R1 by S protein-specific CD4+ T cells was also observed in patients with PAD following COVID-19 mRNA vaccination although the expression levels of IL-1R1 by such cells did not correlate with the levels of serum anti-S protein IgG antibody. In mice immunized with COVID-19 mRNA vaccine, neutralizing IL-1R1 decreased IFN-γ expression by S protein-specific CD4+ T cells and the development of anti-S protein IgG antibody.
Interpretation:
Our results demonstrate the significance of IL-1R1 expression in CD4+ T cells for the development of viral antigen-specific CD4+ T cell responses, contributing to humoral immunity. This provides an insight into the regulation of adaptive immune responses to viruses via the IL-1 and IL-1R1 interface.
Funding:
Moderna to HJP, National Institutes of Health (NIH) 1R01AG056728 and R01AG055362 to IK and KL2 TR001862 to JJS, Quest Diagnostics to IK and RB, and the Mathers Foundation to RB.