Trakia Journal of Sciences, Vol. 8, Suppl. 2, 2010 92 Trakia Journal of Sciences, Vol. 8, Suppl. 2, pp 92-97, 2010 Copyright © 2009 Trakia University Available online at: http://www.uni-sz.bg ISSN 1313-7050 (print) ISSN 1313-3551 (online) ENHANCEMENT OF ANTI-KLH IgG ANTIBODY PRODUCTION IN RABBITS AFTER TREATMENT WITH HABERLEA RHODOPENSIS EXTRACT B. Popov 1 , Zl. Dobreva 1* , Sv. Georgieva 2 , S. Stanilova 1 1 Department of Molecular Biology, Immunology & Genetics, Faculty of Medicine 2 Department of Genetics, Breeding and Reproduction, Faculty of Agriculture Trakia University, Stara Zagora, Bulgaria ABSRACT The immunomodulatory properties of Haberlea rhodopensis extract on primary and secondary specific antibody production were evaluated in New Zealand white rabbits. Rabbits were immunized with 50 µg of keyhole limpet hemocyanin (KLH). Simultaneously with antigen challenge groups of rabbits were injected with: 100 mg/kg Haberlea rhodopensis extract; 50 mg/kg cyclophosphamide or Haberlea rhodopensis extract + cyclophosphamide. The control group of rabbits was injected with KLH, only. Rabbits were reimmunized and treated with plant extract and cyclophosphamide on day 44. The specific anti-KLH total IgM,G, A and KLH-specific IgG antibody production were determined on day 0, 15, 22, 28 for primary and day 43, 51, 58, 66 for secondary antibody response by ELISA. Results showed that KLH-specific IgG antibody production had increased significantly after treatment with H. rhodopensis extract during the secondary humoral immune response. We concluded that, in tested concentration the extract from Haberlea rhodopensis showed a well expressed immunostimmulatory activity on the secondary IgG and in the lower degree on the secondary total IgG,M,A antibody production. Key words: immunostimulation, anti-KLH IgG, anti-KLH IgG,M,A, Haberlea rhodopensis INTRODUCTION Compounds that are capable of interacting with the immune system to upregulate or downregulate specific aspects of the host response can be classified as immunomodulators. Those compounds which appear to stimulate the human immune response are being sought for the treatment of cancer, immunodeficiency diseases, or for generalized immunosuppression following drug treatment; for combinational therapy with antibiotics; and as adjuvants for vaccines (1). Plant extracts are among the attractive sources of new drugs and have been shown to induce promising immunostimulatory effects. Medicinal plants serve as therapeutic alternatives, safer choices, or in some cases, as _____________________________ *Correspondence to: Zlatka Dobreva, Ph.D. Department of Molecular Biology, Immunology & Genetics, Faculty of Medicine, Trakia University Armeiska 11 St., 6000 Stara Zagora, Bulgaria, E-mail address: zdobreva@mf.uni-sz.bg the only effective treatment. A large number of plant extracts and their isolated constituents have shown beneficial therapeutic effects, including anti-oxidant, anti-inflammatory, anti- cancer, anti-microbial and immunomodulatory effects (2). Some of the plants with well established immunostimulatory activity are Viscum album (3), Panax ginseng (4), Echinacea purpurea (5) and Cuscuta europea (6). The Balkan region endemite Haberlea rhodopensis is a world record-holder in desiccation tolerance, but its effect on the immune response is not investigated. Unfortunately, till now there are no strong historical and etnobotanical data confirming the ancients’ knowledge and use of Haberlea as medicinal attribute. However, one of the local plant names in the Rhodopi mountains is “shap” (food and mouth disease) which is considered as confirmation that the local people have used the plant against animal diseases (7). The aim of the present study is to