The ratio between bystander and tumour-specific TILs varies between tumours,28 and this could explain why in OC, with smaller numbers of tumour-specific lymphocytes in comparison to melanoma,11 only CD137+ cells12 or PD-1+ cells containing a high proportion of CD137+ cells (our study) were able to render TR TILs. The gene discussed is PDCD1; the disease is neoplasm.