Acta Pharmacologica Sinica (2009) 30: 597-604; doi: 10.1038/aps.2009.35; published online 13th April 2009

Aim: To investigate the immunosuppressive effect of gossypol in mice both in vitro and in vivo.   

Methods: The in vitro effect of gossypol on the proliferation of lymphocytes isolated from lymph nodes of BALB/c mice was determined by CFSE staining and by an MTS assay.  Lymphocyte activation and lymphoblastic transformation were evaluated with immunostaining.  Cell apoptosis was detected by Annexin-V and Hoechst 33342 staining.  The in vivo immunosuppressive effect of gossypol on the DTH reaction was evaluated using a mouse DTH model induced by 2,4-dinitro-1-fluorobenzene (DNFB).  The thickness of the ears was measured, and the histological changes of the mouse auricles were observed after hematoxylin-eosin staining.  The proliferation capacity of lymphocytes from DTH mice was also assayed. 

Results: In vitro, gossypol could significantly inhibit the proliferation of mouse lymphocytes stimulated with phorbol ester plus ionomycin in a dose-dependent manner.  Although the expression of the early activation antigen CD69 was not affected, the lymphoblastic transformation of both T and B lymphocyte subsets was significantly suppressed by gossypol.  Moreover, gossypol could induce apoptosis of lymphocytes, and the effect was time- and dose-dependent.  In vivo, the DTH reaction in mice was markedly alleviated by gossypol injected intraperitoneally.  Lymphocytes from drug-treated DTH mice had a reduced proliferation capacity as compared with lymphocytes from untreated DTH mice.  Gossypol treatment also markedly reduced the number of infiltrated lymphocytes in the auricles of DTH mice. 

Conclusion: Gossypol exhibited immunosuppressive effects in mice, probably by inhibition of lymphocyte proliferation and by induction of cell apoptosis.

Keywords: gossypol; lymphocytes; cell proliferation; apoptosis; delayed-type hypersensitivity