A Lochmanova and Ivo Lochman
Cytomegalovirus is one of the most immunodominant antigens that are encountered by the human immune system. The human cytomegalovirus (HCMV) exhibits a broad cellular tropism and can infect most major organ systems and cell types. Immunologic control of HCMV replication includes several distinct categories of effector cells: natural killer cells, macrophages, B cells and T cells however virus-specific CD8+ and CD4+ T cells appear to play a pivotal role. The importance of cell mediated immunity against CMV is exemplified by the occurrence of severe and prolonged HCMV infection in immunocompromised individuals, including transplant recipients, late stage -HIV patients, congenitally infected neonates, elderly subjects and/or septic patients. Severely impaired T-cell function leads to viral reactivation and consequences are widely variable, ranging from asymptomatic infections to life-threatening situations. Monitoring of protective HCMV-specific immune response may serve as an early predictive marker for identifying individuals at high risk for HCMV disease prior to the detection of increased viremia. The identification of patients who are at high risk of CMV is a more complex challenge for the laboratory. Mainly HCMV specific T cell immunity, resp. enumeration of CD8+ HCMV specific T cells would be expected to correlate with the incidence of HCMV disease. Recently, it has become possible to enumerate antigen-specific CD8+ T cells by using tetramers. HCMVspecific cellular immunity by evaluating the activation capacity of CD8+ T cells to a mitogenic stimulus or whole HCMV antigen or HCMV peptides assessed by IFNγ ELISPOT or ELISA seem to be promising in the assessment of HCMV specific function/immunity. However the clinical utility of these assays will need to be evaluated.