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Mice modeling the hemizygous deletion of chromosome 22q11.2 (22qMc) have been utilized to address various clinical phenotypes associated with the disease, including cardiac malformations, altered neural circuitry, and behavioral deficits. Yet, the status of the T cell compartment, an important clinical concern among 22q11.2 deletion syndrome (22qDS) patients, has not been addressed. While infancy and early childhood in 22qDS are associated with deficient T cell numbers and thymic hypoplasia, which can be severe in a small subset of patients, studies suggest normalization of the T cell counts by adulthood. We found that adult 22qMc do not exhibit thymic hypoplasia or altered thymic T cell development. Our findings that immune cell counts and inflammatory T cell activation are unaffected in 22qMc lend support to the hypothesis that human 22qDS immunodeficiencies are secondary to thymic hypoplasia, rather than intrinsic effects due to the deletion. Furthermore, the 22q11.2 deletion does not impact the differentiation capacity of T cells, nor their activity and response during inflammatory activation. Thus, 22qMc reflects the T cell compartment in adult 22qDS patients, and our findings suggest that 22qMc may serve as a novel model to address experimental and translational aspects of immunity in 22qDS. [ABSTRACT FROM AUTHOR]