HHLA2 and diffuse large B-cell lymphoma: Comparing B7-H7 expression level of peripheral T-cell lymphoma patients with that of other haematological cancers, similar levels of expression was observed for B-cell acute lymphoblastic leukaemia (B-ALL) and T-cell acute lymphoblastic leukaemia (T-ALL) whereas Diffuse Large B Cell Lymphoma (DLBCL) and acute myeloid leukaemia (AML) showed lower expression of B7-H7.