There are a number of flow-based assays that we can perform to provide valuable information on a patient's immune response. Using multi-color flow cytometric analysis of up to 7 colors, we can assess the imunophenotype and activation status of different cell populations. This can be combined with fluorescently labeled MHC class I multimers (tetramer or pentamers) to measure the number of CD8+ T cells that recognize a particular antigenic epitope.