Cellular and humoral adjuvant activity of lectins isolated from Korean mistletoe (Viscum album colaratum)

The adjuvant effect of lectins (KML-C) isolated from Korean mistletoe (Visc um album coloratum) on induction of humoral and cellular immune responses a gainst keyhole limpet hemocyanine (KLH) was examined. When mice were immuni zed subcutaneously (s.c.) with KLH (20 mug/mouse) admired with or without 5 0 ng/mouse of KML-C (KLH + KML-C), mice immunized with KLH + KML-C showed s ignificantly higher antibody titers against KLH than those immunized with K LH alone. showing the highest titer 5 weeks after immunization. Furthermore , boost immunization with KLH + KML-C at 2-week interval elicited much high er activity than single immunization to enhance antibody responses against KLH. The assay for determining isotypes of antibodies revealed that KML-C a ugmented KLH-specific antibody titers of IgG1, IgG2a and IgG2b. The culture supernatants obtained from the splenocytes of mice treated with KLH + KML- C also showed a higher level of both KLH-specific Th-l (IL-2 and IFN-gamma) and Th-2 type cytokine (IL-1). In an in vitro analysis of T lymphocyte pro liferation to KLH on week 4, the splenocytes of mice treated with KLH + KML -C showed a significantly higher proliferating activity than those treated with KLH alone, In addition, mice immunized twice with KLH + KML-C and foll owed by intrafootpad (i.f.) injection of KLH (50 mug/site) 14 weeks after t he primary immunization induced a higher delayed-type hypersensitivity (DTH ) reaction than mice treated with KLH alone. These results suggest that KML -C is a potent immunoadjuvant to enhance cellular and humoral immune respon ses. (C) 2001 Elsevier Science B.V. All nights reserved.