CD4 and graft versus host disease: It should also be noted that after day 39, all of the animals receiving either B7-H3-CXCR2 or B7-H3 CAR T cells began to die from graft-versus-host disease, as revealed by immunostaining of multiple tissues and by flow cytometric analysis, which revealed a dense infiltrate of canine CD5+ T cells, both CD4+ and CD8+ (data not shown).