Both "helper" (CD4) and "cytotoxic" (CD8) T-cell classes have been described.

现已明确两类T细胞：辅助性T细胞(CD4)和细胞毒性T细胞(CD8)。

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The CD4 + test directly measures the abundance of the helper t cell, an of immune cell in the bloodstream distinguishable because they are the only ones that carry the CD4 marker.

CD 4 +试验直接检测辅助型T细胞数量。辅助型T细胞是血流中可分辨的免疫细胞中的一种，因为只有他们才具有CD 4标志物。

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