Background: Researches on the pathogenesis and pathological changes of rheumatoid arthritis(RA) have achieved significant progress in recent years. But traditional Chinese medicine(TCM) has unique advantage in RA therapy. Objective: To study effects of overall alkali in tongbiling(TBL) on the proliferation of lymphocytes and the transferrin receptor of T lymphocytes (CD71) to explore the mechanism of TBL on the modulation of cell immunity. Design: A completely randomized grouping design and an explorative study by employing cells as subjects. Setting: Sixth internal medicine department of a TCM university, center of tissue transplantation and immunology college of life science of a university. Participants: The study was conducted in the central laboratory (tertiary laboratory of National TCM Administrator) of the first affiliated hospital of Guangzhou TCM medical university between July 2002 and August 2003. Ten clean male SD rats were selected. Methods: Lymphocyte was separated from rat inguinal lymph node for culture. Concanavalin(ConA) was used for 72-hour stimulation. The impacts of overall alkali TBL on lymphocyte proliferation were tested by MTT. The expression of T lymphocyte CD71 was tested by flow cytometer after 48-hour stimulation of phorbol 12, 13 - dibutyrate(PDB) or ConA. Main outcome measures: The impacts of overall alkali TBL on lymphocyte proliferation and T cell activation. Results: Different concentration of overall alkali TBL could significantly inhibit the proliferation of lymphocytes under ConA stimulation. PDB and ConA-activated T lymphocyte CD71+ expressions were significantly higher than that of blank control group(P < 0.01). CD3+ CD71+ expressions [(62. 03 ± 1. 51)%, (25. 28 ± 1. 57)%, (20. 29 ± 1. 72)%] activated by ConA under different concentration of overall alkali TBL(50, 100, 200 mg/L), were significantly lower than (72. 03 ± 1. 28)% of BPS-positive control group (P < 0. 05). CD3+ CD71+ expressions activated by PDB under 100 mg/L and 200 mg/L of overall alkali TBL were significantly lower than that of phosphate buffer solution (PBS-)positive control group(P < 0. 05). Different concentration of overall alkali TBL had significant down-regulated effects on CD71 expression in T lymphocyte activated by PDB or ConA and there was also a significant close-effect relationship (P < 0. 05). The inhibition on ConA-activated CD71 expression was stronger than that of PDB. Conclusion: Overall alkali TBL can inhibit the abnormal proliferation of T lymphocyte and its mechanism might be realized through its inhibition on transferrin receptor.