Evaluation of Fc gamma RIIIB-NA1/NA2 Polymorphism in Visceral Leishmaniasis

Abstract

Background: Several lines of evidence demonstrating that innate and adaptive immunity play important roles in the defense against visceral leishmaniasis (VL). A polymorphism within the Fc gamma RIIIB gene can lead to the expression of three variants of NA1, NA2, and the combined one (NA1/NA2) which alters affinity of IgG to its receptor. Objectives: The main aim of this study was to evaluate the Fc gamma RIIIB-NA1/NA2 polymorphism in the Fc gamma RIIIB gene of VL patients in comparison to healthy controls. Patients and Methods: In this cross-sectional study, three groups; 54 seropositive patients with clinical presentation of VL (group 1), 104 seropositive patients without clinical presentation (group 2), and 104 healthy controls (group 3) were evaluated with respect to the Fc gamma RIIIB-NA1/NA2 polymorphism using a PCR-SSP method. The titration of anti-leishmania antibodies was analyzed using an immunoflorescence technique. Results: Our results indicated that polymorphisms within the Fc gamma RIIIB gene (that lead to the expression of the NA1/NA2 isoforms) are significantly associated with VL. The results demonstrated that the genotype heterozygotic for Fc gamma RIIIB-NA1/NA2 expression was significantly increased in VL patients, group 1 when compared to groups 2 and 3. Conversely, there is a decrease in homozygous NA1 and NA2 genotypes in VL patients; however, the overall frequency of NA1 and NA2 alleles appear similar across the three cohorts examined. Conclusions: According to our results, it is likely that the increased frequency of the Fc gamma RIIIB-NA1/NA2 genotype is associated with impaired immune responses against VL and its subsequent clearance from the patient.