Development of mixed Th1/Th2-type immune response in mice following immunization with GP63 from Leishmania donovani

내장리슈만편모충 유래 GP63 항원을 마우스에 접종한 후 관찰되는 Th1/Th2-type 복합 면역반응

  • Accepted : 2001.05.30
  • Published : 2001.06.25

Abstract

The $M_r$ 63,000 glycoprotein (GP63) and lipophosphoglycan (LPG) of Leishmania donovani were evaluated as vaccine candidates against visceral leishmaniasis. Mice were immunized with liposomeencapsulated GP63 and/or LPG that were purified from the soluble extract of L. donovani promastigotes, and were challenged with virulent amastigotes. Mice immunized with GP63/LPG in liposomes plus BCG resulted in a 27.4% reduction of amastigotes in the liver compared to the control group (liposomes plus BCG), and mice immunized with liposome-GP63 plus BCG failed to induce a protective immune response against the challenge infection. Immunization of mice with GP63 fused to the Schistosoma japonicum glutathione S-transferase (GP63-GST) plus BCG also failed to elicit protective immunity. To analyze the cause of failure to induce protection, cytokine release from the spleen cells of immunized mice and Leishmania-specific serum antibodies were analyzed. Spleen cells from mice immunized with GP63-GST plus BCG that were exposed to soluble extract of L. donovani in vitro produced 10-fold greater quantities of IFN-gamma and 3-fold greater quantities of IL-5 than cells from mice receiving BCG only or saline. Western blot analysis revealed that sera from these mice had Leishmania-specific antibodies recognizing 1 to 3 antigens of L. donovani with M. W. of 60-65 kDa. Although immunization of mice with GP63-GST induced a strong Th1 response, this study indicated that GP63-GST simultaneously elicited the Th2 response of the CD4+ T-cell, which was known to abrogate the protective immune response conferred by the Th1 effector function.

Keywords

Leishmania donovani;Th1;Th2;gp63;cytokine