OBJECTIVETo observe the effect of Chinese herbal extract HuNan A-1 (HNA-1) on the thymic output function in Simian immunodeficiency virus (SIV) chronically infected rhesus macaques.

METHODSEight Chinese rhesus macaques had been infected by SIVmac239 for 16 to 21 months, and then they were randomly divided into the treatment group and the control group, 4 in each group. Monkeys in the treatment group were administered with HNA-1 by gastrogavage, once daily for 2 successive months, while those in the control group were administered with equal volume of normal saline by gastrogavage, once daily for 2 successive months. The general condition and body weight of monkeys were observed. Plasma viral loads were detected using real-time fluorescent quantitative PCR assay. CD4 percentages and counts, as well as naive CD subsets were detected using flow cytometry. T-cell receptor excision circles (TREC) were detected using real-time fluorescent quantitative PCR assay. The thymus tissue was pathologically observed using routine HE staining. The correlation between lesions of the thymus tissue, CD4 counts, naive CD counts, and TREC were analyzed.

RESULTSThere was no statistical difference in body weight, viral loads, absolute CD ratios between the two groups after treatment (P > 0.05). The altered TREC multiple showed an obvious decreasing tendency in the control group, while it showed an increasing tendency in the treatment group (P < 0.05). In both groups, destroyed structures of the thymus tissue could be seen, filled with pink unstructured material. Increased connective tissues, lowered connective cell density, and confused arrangement could also be seen in the two groups, with no obvious difference. TREC contents were positively correlated with naive CD4 counts after removing extremum (r = 0.926, P = 0.001). Naive CD4 counts were positively correlated with CD4 counts (r = 0.961, P = 0.005).

CONCLUSIONSTREC content determination, as a marker of newly thymic emigrants, could be taken as a testing method for evaluating the thymic output function. Besides, HNA-1 treatment increased the thymic output significantly in SIV chronically infected monkeys. Correlation existed among TREC contents, naive CD4 counts, and pathologies of thymus tissues, especially in late infection stage.