Inflammation in common variable immunodeficiency is associated with a distinct CD8<sup>+</sup> response to cytomegalovirus
Marashi SM., Raeiszadeh M., Workman S., Rahbar A., Soderberg-Naucler C., Klenerman P., Chee R., Webster AD., Milne RSB., Emery VC.
Background: Common variable immunodeficiency is the most common primary immunodeficiency. A subset of patients has debilitating inflammatory complications. Objectives: We investigated the role of cytomegalovirus (CMV), and the T-cell response targeted at this virus, in this inflammatory disease. Methods: Phenotypic and functional assays were used to profile CMV-specific T cells in patients with common variable immunodeficiency with and without inflammatory complications. Highly sensitive immunohistochemistry was used to detect CMV antigens at sites of inflammation. Results: Cytomegalovirus was significantly associated with inflammatory disease, which occurred in 31 of 43 (72%) virus-exposed patients and 8 of 31 (26%) naive patients (P = .0001). CMV pp65-NLVPMVATV epitope-specific CD8+ T-cell frequencies were significantly elevated in inflammatory patients, but these cells did not show evidence of exhaustion, with low levels of programmed death-1 and high T-cell receptor avidity. Rather, they showed features consistent with high in vivo functionality and proliferative activity including reduced levels of the anti-inflammatory marker CD73 (1.67% of NLV+ cells were CD73 + vs 42.01% in noninflammatory patients; P = .004) and increased Ki-67 expression (37% vs 2% in noninflammatory patients; P < .0001). In vitro, the CMV-specific T cells showed high antigen-specific proliferative potential compared with cells from noninflammatory patients. By using sensitive immunohistochemistry, we detected for the first time viral antigen at the sites of inflammation, indicative of active viral replication. Conclusion: Our data strongly support a direct role for CMV and a hyperreactive CMV-specific immune response in the debilitating chronic inflammatory complications of common variable immunodeficiency. © 2011 American Academy of Allergy, Asthma & Immunology.