IL-4 induces CD22 expression to restrain the effector program of self-reactive virtual memory T cells

Parasitic helminths induce the production of interleukin (IL)-4 which causes the expansion of virtual memory CD8+ T cells (TVM), a cell subset contributing to the control of viral coinfection. However, the mechanisms regulating IL-4-dependent TVM activation and expansion during worm infection remain ill defined. We used single-cell RNA sequencing of CD8+ T cells to investigate IL-4-dependent TVM responses upon helminth infection in mice. Gene signature analysis of CD8+ T cells identified a cell cluster marked by CD22, a canonical regulator of B cell activation, as a specific and selective surface marker of IL-4-induced TVM cells. CD22+ TVM were enriched for IFN-γ and granzyme A and retained a diverse TCR repertoire, while enriched in CDR3 sequences with features of self-reactivity. Deletion of CD22 expression in CD8+ T cells enhanced TVM responses to helminth infection, indicating that this inhibitory receptor modulates TVM responses. Thus, helminth-induced IL-4 drives the expansion and activation of self-reactive TVM in the periphery that is counter-inhibited by CD22