CD4 and cutaneous mastocytosis: CD4+ and CD8+ T cells, γδ T cells, natural killer cells (NK), NKT cells, neutrophils, and macrophages can adhere or sequester to the brain microvessels in ECM mice6, 26, 27, 28 and children with CM,14 but CD8+ T cells play an irreplaceable role in the pathogenesis of CM.