Garlic extracts stimulate proliferation of rat lymphocytes in vitro by increasing IL-2 and IL-4 production

Garlic components are known to modulate certain immune functions. However, mechanisms of their action are not sufficiently elucidated. This study was, therefore, undertaken to examine the effects of aqueous and ethanolic extr acts prepared from a garlic powder sample on proliferation of rat spleen ly mphocytes in culture. Cells were stimulated with the combination of phorbol myristate acetate (PMA) and a Ca ionophore (A23187) or R73 monoclonal anti body (mAb) directed to the alpha beta chain of T cell receptor. It has been shown that both extracts significantly stimulated proliferation of lymphoc ytes. The effect correlated with upregulation of the Interleukin 2 receptor alpha (IL-2R alpha) expression and the increase in IL-2 production. Stimul ation of IL-2 production by the extracts was higher in cultures with PMA / Ca ionophore than in cultures with R73 mAb. In contrast, both extracts stim ulated production of IL-4 by splenocytes triggered by R73 mAb. The complete dependence of lymphocyte proliferation in cultures with R73 mAb and garlic extracts on IL-2 and IL-4 was demonstrated using neutralising mAbs to IL-2 R alpha and IL-4. These results suggest that the potentiating effect of gar lic extracts on lymphocyte proliferation in vitro differs depending on spec ific stimulators of cell proliferation and probably on the type of respondi ng cells.