Immunodiagnostics: Evaluation of functional T-cell immunocompetence in whole blood independent of circulating cell numbers

The need for a systematic approach for immune function monitoring has becoming increasingly apparent in the past decade due to the rapid expansion of the development and use of immunomodulatory drug therapies and vaccines. While there has been a great deal of progress in the development of methodologies for evaluating and enumerating T-lymphocyte responses to infection and cancer, the translation of these assays into the clinical setting has remained seemingly elusive. This is likely due to inherent difficulties in the standardization and validation of cell-based assays. Here, we describe a novel assay that measures ATP production in CD4(+) T-lymphocytes in response to stimulation. Results from the test, unlike absolute cell counts, assess the functional response of lymphocytes. Clinical utility of the assay has been demonstrated in managing immunosuppression in solid organ transplant recipients such that adverse events such as infection and rejection can be avoided. The need for a global immune response test in the clinical setting of transplantation and the value of such a test in post-transplant management is discussed. Furthermore, additional applications of this assay for monitoring diseases that impact immune function including autoimmunity and infection are considered.