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.