NEW MICROBIOLOGICA, 32, 285-291, 2009 Determination of the expression of lymphocyte surface markers and cytokine levels in a mouse model of Plasmodium berghei * Funda Dogruman-Al 1 , Isil Fidan 1 , Semra Kustimur 1 , Kemal Ceber 2 , Turgut Imir 1 1 Gazi University Faculty of Medicine, Department of Medical Microbiology, Besevler, Ankara, Turkey; 2 Nigde Goverment Hospital, Microbiology Laboratory, Nigde, Turkey Corresponding author Funda Dogruman-Al Gazi University School of Medicine Department of Microbiology and Clinical Microbiology, 06500, Besevler, Ankara, Turkey E-mail: alfunda@gazi.edu.tr INTRODUCTION Out of the 350-550 million malaria cases esti- mated to occur in the world every year, only around 1-2% are severe or life-threatening (Carneiro et al., 2005). However, this small pro- portion represents an enormous malaria death toll per year, especially in sub-Saharan Africa, where more than 90% of the malaria deaths are thought to take place every year, affecting main- ly children and pregnant women (Snow et al., 2005). Plasmodium berghei (P. berghei) ANKA murine malaria has many features in common with human disease and is thus the best available model for certain important aspects of clinical malaria (Shofield and Grau, 2005). A detailed analysis of the mechanisms of protective immu- nity, its broad specificity and regulation as well as a potential role in pathology is most readily ap- proached by the use of experimental animal mod- els. P. berghei ANKA is uniformly lethal (via cere- bral involvement) in all strains of mice infected (Langhorne et al., 2002). Malaria disease manifestations vary with age and the acquisition of immunity, genetic polymor- phism of host and parasite and regional varia- tions and these manifestations appear to be reg- ulated by the same factors (Eckwalanga et al., 1994). This study aimed to determine the changes in lymphocyte surface markers and cytokine profiles during a malarial in- fection in a mouse model of malaria. Mononuclear cells obtained from the spleens of the mice infected with Plasmodium berghei (P. berghei) were stained with anti-mouse CD3, anti-mouse CD4, anti-mouse CD8, anti-mouse CD19, anti- mouse CD152, anti-mouse pan natural killer (NK), anti-mouse CD80 monoclonal antibodies and expression of surface markers was evaluated by flow cytometry. In the serum samples of the mice, the levels of tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), transforming growth factor-1beta (TGF-1β), and interleukin (IL)-4, IL-10, and IL-12 cytokines were determined by ELISA method. The expressions of all the surface markers of lymphocyte evalu- ated were statistically significantly lower in the infected mice than in the healthy control mice (p<0.05). However, ex- cept for the level of TGF-1β, the levels of all the other cytokines evaluated were statistically significantly higher in the infected group than in the control group (p<0.001). No significant differences were determined between the TGF-1β levels of the study and control groups (p>0.05). In this study, T, B, and NK lymphocyte responses were inhibited and cytokine profiles changed in the course of malarial infection. Thus, interventions to increase the Th1 lymphocyte re- sponse may be beneficial in the prevention of malarial infection. KEY WORDS: Plasmodium berghei, cytokine, lymphocyte surface markers, pathogenesis SUMMARY Received December 12, 2008 Accepted March 04, 2009 *Presented at the XIIth International Congress of Bacteriology and Applied Microbiology, 5-9 August 2008, Istanbul, Turkey, poster no: 1766.