Antirheumatic effect of IDS 23, a stinging nettle leaf extract, on in vitro expression of T helper cytokines

Objective, Stinging nettle leaf extracts are registered in Germany for adju vant therapy of rheumatic diseases. In a whole blood culture system the net tle extract IDS 23 (Rheuma-Hek(R)) inhibited lipopolysaccharide stimulated monocyte cytokine expression, indicating an immunomodulating effect. We inv estigated the immunomodulating effects of IDS 23 on phytohemagglutinin (PHA ) stimulated peripheral blood mononuclear cells (PBMC) in vitro. Methods. Using commercial immunoassays the distinct cytokine patterns of Th 1 and Th2 cells were determined. Interleukin 2 (IL-2) and interferon-gamma (IFN-gamma) mRNA expression was evaluated by reverse transcription-polymera se chain reaction (RT-PCR) with PHA stimulated PBMC. Results, IDS 23 inhibited PHA stimulated production of Th1-specific IL-2 an d TFN-gamma in PBMC culture (n = 10) in a dose dependent manner up to 50 +/ - 32% and 77 +/- 14%, respectively. In contrast, IDS 23 stimulated the secr etion of Th2-specific IL-4. The dose dependent inhibiting effect on LI-2 an d IFN-gamma expression was also detected with RT-PCR, while the amount of a ctin-specific mRNA transcript was not modified by IDS 23. Conclusion. Our results suggest the effective ingredient of IDS 23 acts by mediating a switch in T helper cell derived cytokine patterns. IDS 23 may i nhibit the inflammatory cascade in autoimmune diseases like rheumatoid arth ritis.