Using the method outlined in Fig. 1, T cells specific for viral and tumour antigens were identified and sorted in two steps: following a preliminary enrichment for CD4+ IFN-γ+ and CD8+ IFN-γ+ T cells using a MoFlo cell sorter, single IFN-γ+ cells were then deposited into individual wells of a 96 well plate using a FACS Vantage SE cell sorter. The gene discussed is CD4; the disease is neoplasm.