Now, there are two main types of T cells, CD4 T cells and CD8 T cells - where " CD" stands for cluster of differentiation.

T细胞主要分为两大类，CD4 T细胞和CD8 T细胞；这里“CD”的意思是白细胞分化抗原/分化簇。

Various immune cells, including B-cells have surface proteins or markers that are called CD, short for cluster of differentiation, along with a number - like CD19 or CD21.

包括B细胞在内的各种免疫细胞都有表面蛋白或标记物，称为CD，分化簇的英文缩写，后面常跟数字，如CD19或CD21。