To minimize or prevent the spread of an acute virus infection, the antiviral immune response must detect and lyse virus-infected cells before virus replicates or is released from the host cell. The immune response has developed both innate and specific responses to meet this objective. Virus-infected cells are lysed by cells of the innate immune response such as activated macrophages and natural killer cells, and by cytokines like tumor necrosis factor (TNF) (1 ,2 ). Here, we will discuss methods we developed to measure the cytotoxic capacities of TNF against adenovius-infected cells.