CD4 and cancer: CD4+ T cell–B cell interaction relies on CD40–CD40L costimulatory signals, which mediate the generation of memory B cells and the formation of the GC,199, 200 which is positively associated with a favorable prognosis for a variety of cancers.201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214