CD4 and classic Hodgkin lymphoma: Such a model is supported by the observation of variation at position 86 of HLA-DRB1 influencing TCR Vα gene expression55, the predominance of CD4+ T-cells in cHL tumours56, the reliance of HRS cells on the micro-environment for survival1, and the loss of MHC class II expression on HRS cells57, the last of which is associated with adverse prognosis.