Bioactivity-guided identification to delineate the immunomodulatory effects of methanolic extract of Nigella sativa seed on human peripheral blood mononuclear cells.

OBJECTIVE To study the immunomodulatory effects of Nigella sativa (NS) on human peripheral blood mononuclear cells (PBMCs) on a Phytohemagglutinin (PHA) and a non-PHA stimulated proliferation. METHODS Cells isolated from human PBMCs which were treated with methanolic extract of NS for 48 h into two separate environments (PHA and non-PHA stimulated). Flow cytometry (for T helper/inducer cells and natural killer cells) and real time-polymerase chain reaction (PCR) assays for a few selected proinflammatory gene expressions were performed. RESULTS Extracts from NS had an immunostimulating effect on non-PHA-stimulated proliferation of human PBMCs. In contrast, immunosuppressive activity was observed on PHA-stimulated proliferation of human PBMCs. CONCLUSION This in vitro study revealed the effects of NS plant extract on nonspecifific cellular immune responses.