APA-01, which is an aqueous extract of five Chinese herbs, is a modified formula of Huoxiang-Zhengqi-San. The effect of new herb extract on immune response was investigated. The parameter examined to assess apparent immune response of APA-01 in mice included changes of body weight, relative weight of immune organs, cell proliferation and cytokine gene expression. The body weight and relative weight of immune organs were not significantly changed among the tested groups. In the spleen cell prolijeration assay, APA-01 increased the cell proliferation in a dose-dependent manner. Methotrexate (MTX), an agent of immune suppression, inhibited the spleen cell proliferation (IC50: 800㎍/㎖). However, APA-01 significantly inhibited the suppression of mouse spleen cell proliferation. Therefore, it seems that APA-01 has a reducing effect of immune suppression. Immunomodulatory effect of APA-01 was further investigated using reverse transcription polymerase chain reaction (RT-PCR) in mouse spleen cells. In RT-PCR test, APA-01 enhanced the expression of cyclooxygenase-2 (COX-2) mRNA in a dose-dependent manner. In spite of immune suppression by MTX, COX-2 mRNA was induced by co-treatment with APA-01. These results suggest that APA-01 stimulates the proliferation of spleen cells, regulates the expression of COX-2 mRNA, and accelerates the recovery of inhibition of spleen cell proliferation induced by MTX, thus providing the immunological basis for clinical benefit of APA-01.
