doi: 10.1111/j.1744-313X.2005.00524.x © 2005 Blackwell Publishing Ltd, International Journal of Immunogenetics 32, 285–291 285 Blackwell Publishing, Ltd. Frequencies of the common promoter polymorphisms in cytokine genes in a Polish population M. Kurzawski, A. Pawlik, B. Czerny, L. Domanski, J. Rózanski & M. DroΩdzik Summary Common polymorphisms in cytokine genes, widely distrib- uted in many populations, may affect gene transcription, leading to individual variations in cytokine levels. Some of those polymorphisms were associated with the risk of graft rejection or autoimmune and parasitic diseases development as well as treatment outcome. In the current study the frequencies of promoter polymorphisms in genes encoding interleukin-2 (-330 G/C), interleukin-4 (-590 C/T), interleukin-6 (-174 G/C), interleukin-10 (-1082 G/A, -592 C/A) and TNFα (-307 G/A) have been studied in a sample of 205 unrelated healthy Polish subjects of Caucasian origin. The frequencies of the determined cytokine alleles were as follows: interleukin-2 (-330 G/C): T - 64.9%, G -35.1%; interleukin-4 (-590 C/T): C -79.8%, T -20.2%; interleukin-6 (-174 G/C): G -53.4%, C - 46.6%; interleukin-10 (-1082 G/A, -819 G/ T, -592 C/A): GCC - 44.1%, ACC -32.0, ATA -23.9%; TNFα (-307 G/A): G -85.1%, A -14.9%. We also compared our results with other populations studied to date, describing some significant differences. Introduction Cytokines are key mediators in the induction and effector phases of all immune and inflammatory responses. Marked differences in the magnitude and profile of cytokine response to a number of immunogens among individuals in human populations during in vitro and in vivo studies have been noted. Mechanisms of the observed differences are likely to be diverse, but one of them is the variation in cytokine genes. Recently, a number of polymorphisms have been identified in coding regions (e.g. IL-2, LT-α), promoters (IL-1α, IL-1β, IL-1ra, IL-2, IL-4, IL-6, IL-10, TNFα), introns (IL-1α, IL-1ra, TNFα, LT-α, IFNγ), and 3′-flanking regions (IL-6, TNFα) of cytokine genes. Several of those have been associated with altered levels of cytokine production or activity and with susceptibility to various infectious agents, autoimmune diseases and allergy in humans. In this study, the frequency of common promoter single nucleotide polymorphisms (SNPs) in five cytokine genes (IL-2, IL-4, IL-6, IL-10 and TNFα) in 205 unrelated healthy Polish subjects were examined. This is an attempt to evaluate the frequency of cytokine genotypes and alleles in a Polish population. Materials and methods Subjects Two hundred and five unrelated healthy Polish subjects of Caucasian origin, 112 males and 93 females, age 21 to 72 years (mean 45.5) were included in this study after giving informed consent. The population of Poland, a country with almost 40 million inhabitants, is ethnically quite homogenous — it is estimated that over 95% of citizens are of Caucasian origin. The Ethic Committee of the Pomeranian Medical University in Szczecin, Poland, approved the protocol of the study. Genotyping Genomic DNA was extracted from 450 μL of whole blood samples using a non-organic and non-enzymatic extraction method (Lahiri et al., 1992). Genotyping of each subject for the presence of common polymorphisms in promoter regions of the studied cytokine genes was performed using previously described PCR-based assays (Wilson et al., 1992; Cantagrel et al., 1999; Edwards-Smith et al., 1999; Reynard et al., 2000; Donn et al., 2001) with minor modi- fications. We have selected an allele-specific PCR method for detection of IL-2–330 G/C promoter polymorphism and PCR / RFLP methods for detection of polymorphisms in promoter regions of IL-4 (-590 C/ T), IL-6 (-174 G/C), IL-10 (-1082 G/A, -592 C/A) and TNFα (-307 G/A) genes. It was shown previously that polymorphic sites in IL-10 gene (SNPs at positions -1082, -819 and -592) in Caucasian populations are at full linkage disequilibrium and they form only three (of eight potentially possible) haplotypes (GCC, ACC, ATA) (Turner et al., 1997). Therefore, in the current study we analysed only two of three polymorphic sites (-1082, -592) to determine IL-10 Department of Pharmacology, Pomeranian Medical University, Szczecin, Poland Received 6 October 2004; revised 21 February 2005; accepted 7 June 2005 Correspondence: Mateusz Kurzawski, Department of Pharmacology, Pomeranian Medical University, Powsta˜ców Wlkp. 72, 70 –111 Szczecin, Poland. Tel.: +48 9146 61589; Fax: +48 9146 61600; E-mail: mkurz@op.pl