Reduced numbers of circulating group 2 innate lymphoid cells in patients with common variable immunodeficiency.

Recent studies identified an emerging role of group 2 and 3 innate lymphoid cells (ILCs) as key players in the generation of T-dependent and T-independent antibody production. In this retrospective case-control study, CD117(+) ILCs (including the majority of ILC2 and ILC3) were reduced in patients with common variable immunodeficiency (CVID). The reduction in CD117(+) ILCs was distinctive to CVID and could not be observed in patients with X-linked agammaglobulinemia. Patients with a more pronounced reduction in CD117(+) ILC numbers showed significantly lower numbers of peripheral MZ-like B cells and an increased prevalence of chronic, non-infectious enteropathy. Subsequent phenotyping of ILC subsets in CVID revealed that the reduction in CD117(+) ILC numbers is due to a reduction in ILC2 numbers. In vitro expansion of CVID ILC2 in response to IL-2, IL-7, IL-25 and IL-33 was impaired. Furthermore, upregulation of MHCII and IL-2RA in response to IL-2, IL-7, IL-25 and IL-33 was impaired in CVID ILC2. Thus, our results indicate a dysregulation of ILC subsets with a reduction in ILC2 numbers in CVID, however, further studies are needed to explore whether ILC abnormalities are a primary finding or secondary to disease complications encountered in CVID.