The CD4⁺/CD8⁺ ratio is used as a marker of the immune regulation of T cell balance. When the ratio in peripheral blood is less than 1, this is considered an indication of immune suppression in an individual. Previous work on bovine Peripheral Blood Mononuclear Cells (PBMC) has consistently reported a ratio ≥1 as seen in other mammalian hosts, i.e. higher circulating CD4⁺ cell numbers than CD8⁺ cell numbers. However, a consistent inverted CD4⁺/CD8⁺ ratio (<1) was observed in Boran cattle, an African Bos indicus breed. The T cell populations were characterized in Boran cattle (n = 52), revealing higher percentages of circulating CD8⁺ cells (31.9 % average) than CD4⁺ cells (19.1 % average), thus resulting in the inversion of the expected T cell homeostasis in these animals. The results show that this inversion is not an effect of age or relatedness of the cattle, rather, it was shared by almost all Boran cattle used in this study. Despite this inversion being a feature shared by both males and females, the female cattle had significantly higher CD4⁺/CD8⁺ ratios than the male Boran.

This paper describes the characteristics of the T cell fractions in the study animals and compares the findings to those of other Boran cattle in Kenya, and four other cattle breeds representing African indicine, African taurine, Brazilian indicine and European taurine cattle. We demonstrate that the consistent observation of inverted CD4⁺/CD8⁺ cell ratio was restricted to the Boran.

CD4 ⁺ / CD8 ⁺比率用作T细胞平衡免疫调节的标志物。当外周血的比率小于1时，这被认为是个体免疫抑制的指示。以前关于牛外周血单个核细胞（PBMC）的研究一致报告该比率≥1，如在其他哺乳动物宿主中所见，即循环CD4 ⁺细胞数高于CD8 ⁺细胞数。然而，在非洲Bos indicus品种Boran牛中观察到一致的反向CD4 ⁺ / CD8 ⁺比值（<1）。在Boran牛（n = 52）中对T细胞种群进行了表征，发现循环CD8 ^+的百分比更高细胞（平均31.9％）比CD4 ⁺细胞（平均19.1％）高，因此导致这些动物的预期T细胞体内平衡发生逆转。结果表明，这种倒置不是牛的年龄或亲缘关系的影响，而是本研究中使用的几乎所有博兰牛都具有的这种倒置。尽管这种反转是雄性和雌性共有的特征，但雌性牛的CD4 ⁺ / CD8 ⁺比明显高于雄性Boran。

本文描述了研究动物中T细胞组分的特征，并将发现的结果与肯尼亚的其他Boran牛以及代表非洲标志，非洲牛磺酸，巴西标志和欧洲牛磺酸的其他四个牛品种进行了比较。我们证明反转CD4 ⁺ / CD8 ⁺细胞比率的一致观察仅限于Boran。