OBJECTIVETo study the effects of the Rich Selenium-Banqiao-Codonopsis Pilosula (BCPA) injecta on the aged rats' immune functions and its underlying mechanism.

METHODSTotally 60 rats, composed of 2, 12 and 22 month age old (half male and half female), were served as a young group, middle-age group and aged group respectively. Each group rats were randomly divided into the control and the BCPA subgroup (n = 10). The BCPA group was injected with BCPA at 7.2 g/kg intraperitoneally every day and the control group was injected the same volume of normal saline. All rats were conventionally fed for 45 days. An immune injection was performed after 15 days of BCPA injection. On the 22nd day, late-onset immune response would be induced. The caudal vein blood was collected and the antigen specific IgG, IgG1 and IgG2a antibody was detected on the 15th, 30th and 45th day. On the 45th day, the major T cell subgroups of splenic cells were analyzed and splenic cells were proliferated.

RESULTSNo significant difference in the delayed-type hypersensivity (DTH) reaction was found between the control and the BCPA subgroups in the young and middle-aged rats while the aged BCPA subgroup had a stronger DTH reaction. There was no significant difference in the blood content of specific IgG, IgG1 and IgG2a antibody between the young and middle-age BCPA group while the aged BCPA group rats had an obvious enhancing reaction to the three antibodies mentioned above (P < 0.05). There was no obvious difference in the number of the CD3+ lymphocytes and the CD4+ T helper lymphocytes between the control and the BCPA subgroup in the young aged rats while a significant increase was spotted between the middle-aged and the aged group (P < 0.05). The splenic cells from young BCPA group rats had a strong proliferation response (P < 0.05).

CONCLUSIONBCPA can enhance DTH reaction, potentiate the production of specific IgG, IgG1 and IgG2a antibody to resist KLH, improve the reaction to antigen, increase the amount of CD4+ cell, promote the immune response and had an important role in anti-immunosenescence and antioxidant capacity improvement in the aged rats.