PDCD1 and common variable immunodeficiency: Similarly, a disproportionate increase in terminally differentiated, senescent T cells (CCR7−CD45RA+) which are positive for CD57 and PD-1 was found across multiple studies, further supporting the presence of a persistent, unregulated cellular immune response in CVID.6, 17, 26, 27 Unlike T-cell proliferation and cytokine output, immunophenotypic findings are more consistent across studies and affect a larger proportion of patients with inflammatory complications such as polyclonal proliferation, chronic enteropathy, interstitial lung disease and autoimmunity.