Oral administration of aqueous extract of Carthami Flos induces macrophage activation and preferentially potentiates type 1 helper T-cell response in vivo.

In vivo immunomodulatory activity of aqueous extract of Carthami Flos (AECF) was investigated using a mouse model immunized with keyhole limpet hemocyanin. Serum level of Ag-specific IgG2a was significantly elevated by oral administration of AECF but not IgG1. However, no selective B-cell proliferation by AECF was observed in vivo. Ag-specific proliferation and IFN-gamma and IL-5 production of draining lymph node T cells also was higher in AECF-treated mice when compared with water-treated control mice. However, AECF failed to enhance nonspecific T-cell response under CD3 stimulation. These results led us to hypothesize that AECF potentiates Ag-specific T-cell response, possibly through activation of antigen presenting cells (APC) other than B cells. Functional assessment of splenic macrophages showed that AECF administration significantly enhances IL-12 production as well as APC activity for IFN-gamma production and STAT-4 activation by T cells. Collectively, these data strongly support that AECF preferentially potentiates immune response polarized toward TH1 and for which increased activation of macrophages is most likely to be responsible. The present data implicate a possible application of AECF to potentiate cellular immunity and, we hope, prevent intracellular infections.