Polimorfismo Alélico do receptor FcyRIIA na Leishmaniose Tegumentar Americana
Data
2007-02-13
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Universidade Federal de Goiás
Resumo
The FcγRIIA, receptor for the Fc portion of IgG, expressed by macrophages, neutrophils, platelets and dendritic cells, bind to the subclasses of IgG with variable affinity, that can be influenced by the polymorphism in the gene that encodes this receptor. The substitution of the amino acid arginine (R) for histidine (H), in the 131 position, defines three allelic patterns, the homozygote H/H, R/R and the heterozygote H/R, conferring to the FcγRIIA H/H131 a greater affinity to the IgG2 and IgG3 subclasses. This can result in different responses to diverse pathogens. Studies show the importance of Fcγ receptors on the macrophage infection by amastigote forms of Leishmania sp, in addition to those for the complement (CR3) and for mannose (MR). Besides that, genetic factors related to the hosts are involved in the immune response to the leishmaniasis, among them, the FcγRs. Until this time, we haven t found studies relating the receptor FcγRIIA to the leishmaniasis in humans. This way, this work consists in analyzing the allelic polymorphism in the gene that encodes the FcRIIA in individuals with American Tegumentary Leishmaniasis (ATL), evaluate if this polymorphism would be a genetic fact of susceptibility or resistance for this disease, if this would be influencing in the development of the different clinical forms of the ATL, as well in the healing process of the lesions. The FcγRIIA H/R131 polymorphism was analyzed in 88 blood samples of individuals with leishmaniasis and in 98 samples of healthy individuals (control group), using PCR, amplifying a segment of the gene that encodes the FcRIIA, followed by allele-specific enzymatic digestion and agarose gel eletrophoresis 3%. These results showed that the genotypic and allelic distribution of the FcγRIIA H/R131 were similar in the patients with leishmaniasis and in the control group, as well in patients with different clinical forms of the ATL. Concerning the resolution time of the disease, among the patients that had their lesions healed within one month of treatment or after this period, there was a predominance of the alleles R and H, respectively, however these differences were not significant. This way, our study suggests that the allelic polymorphism of the FcγRIIA H/R131 possibly is not a genetic factor of host that is associated to the protection or pathogenesis in the American Tegumentary Leishmaniasis.
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Citação
OLIVEIRA, Cristina Rodrigues de. Allelic polymorphism in the receptor FcyRIIA Cutaneous Leishmaniasis. 2007. 96 f. Dissertação (Mestrado em Medicina) - Universidade Federal de Goiás, Goiânia, 2007.