H. Bellali

Kell Blood Group System Polymorphism in an Urban Tunisian Population

Blood group systems such as Kell are significant in clinical and basic sciences (Daniels 2005). Their importance has been widely linked to their immunogenicity in some contexts, such as transfusion, feto-maternal tolerance, and transplantation (Lee et al. 1993; Murphy and Fraser 1997; Mannessier 2003; Faas et al. 2000; Kavita and Francine 2001; Dhodapkar and Blei 2001; Daniels et al. 2003; Gariod et al. 2004; Zimring et al. 2007). Such immunogenicity was linked to individual antigens that result from genetic polymorphisms. In this regard, the Kell blood group was described as the third most polymorphic system, with a group of 31 antigens (Körmöczi et al. 2009). Incompatibility for these antigens was defined as a critical factor involved in hemolytic transfusion reactions, autoimmune hemolytic anemia, and hemolytic disease of the newborn (Kanhai et al. 1987; Lee et al. 1993). The Kell carrier molecule (CD238), a zinc endopeptidase, is a 93-kDa type II glycoprotein composed of 732 amino acids. It is encoded by the 19-exon KEL gene assigned to 7q33–35. Depending on single-nucleotide polymorphisms and resulting amino acid substitutions, several sets of antithetical KEL antigens are recognized, such as KEL1 (K) (Lee et al. 1996a) and KEL2 (k, ‘‘cellano’’) (Hessner et al. 1996); KEL3 (Kp), KEL4 (Kp), and KEL21 (Kp); KEL6 (Js) and KEL7 (Js) (Lee et al. 1995a). The most important is the KEL1 (K, ‘‘kell’’) antigen; anti-KEL1 is a commonly encountered allospecificity capable of causing hemolytic transfusion reactions, hemolytic disease of the fetus and newborn, and neonatal anemia (Win et al. 2005). Besides peripheral immunologic clearance of anti-KEL1 sensitized RBCs, it has been reported that these antibodies are able to induce myelosuppression, probably

Killer cell immunoglobulin-like receptor (KIR) locus profiles in the Tunisian population.

Killer cell immunoglobulin-like receptors (KIRs) are a family of inhibitory and activatory receptors that are expressed by most natural killer (NK) cells. The KIR gene family is polymorphic: genomic diversity is achieved through differences in gene content and allelic polymorphism. The number of KIR loci has been reported to vary among individuals, resulting in different KIR haplotypes. In this study we report the genotypic structure of KIRs in 267 unrelated and healthy Tunisian subjects by polymerase chain reaction-sequence-specific primer (PCR-SSP) method. All 16 KIR genes were observed in the population with different frequencies; framework genes KIR3DP1 and KIR3DL2 and the nonframework genes KIR2DL1 and KIR2DP1 were present in all individuals. A total of 26 different KIR gene profiles and 54 subgenotypes were observed in the tested population samples. Genotype 1, with a frequency of 36.6%, is the most commonly observed in the Tunisian population. Our results showed that the Tunisian population possesses the previously reported general features of the Caucasian as well as African populations, with some additional interesting differences. Such knowledge of the KIR gene distribution in populations is very useful in the study of associations with diseases and in selection of donors for haploidentical bone marrow transplantation.