Contribution of the HLA-DRB1 alleles in development of leprosy disease in an Argentinean population

GARCÍA BORRÁS S; GASPARI C; COTORRUELO C; BIONDI C; RACCA L; BOTTASSO O; RACCA A

Macao - China

Congreso; XXX Internationa Congress of the ISBT; 2008

International Society of Blood Transfusion

Background: Leprosy is the clinical syndrome that occurs in genetically predisposed individuals as a result of infection with Mycobacterium leprae (M. leprae). Leprosy is characterized by a spectrum of clinical manifestations, resulting from interactions between the host immune response and the invading M. leprae. Aims: To investigate the contribution of the HLA-DRB1 alleles in development of leprosy disease in subjects that were born in Rosario, Santa Fe. Methods: The study included 71 unrelated individuals with diagnostic of leprosy based on clinical assessment and detection of acid-fast bacilli in skin slit smears and skin lesion histopathology. Additionally, 81 non-related healthy individuals with neither symptoms nor previous diagnosis of leprosy disease were included as a control group. All subjects gave informed consent to participate in the study, and the protocol was approved by the Ethic Committee of the School of Medical Sciences of Rosario, Argentina. Genomic DNA was extracted from peripheral blood using the standard salting out method and used as a template to amplify by the PCR the polymorphic second exon of the HLA-DRB1. PCR products were hybridized separately with sequence-specifics oligonucleotides (SSO). PCR products were dot-blotted and probed with SSOs to assign the DRB1 alleles. Allelic level typing requires a two stage process in which a primary (allele group specific) panel of probes/primers is employed followed by a secondary panel, selected in reference to results obtained with the primary panel, which affords discrimination of individual alleles within the group. Differences in the distribution of HLA-DRB1 alleles between leprosy disease patients and controls were analyzed by or Pearson’s c2-test with Yates correction or Fisher’s exact test if applicable. Odds ratios and relative risks were also calculated. Results: Among leprosy patients alleles occurring at higher frequencies (%) were DRB1*1501 (11.99%), DRB1*0801 (9.87%), DRB1*1401 (9.15%), DRB1*1406 (9.15%) and DRB1*1001 (8.45%). With reference to controls the most prevalent alleles were as follows: DRB1*0701 (14.20), DRB1*1103 (12.96), DRB1*0808 (12.35), DRB1*1303 (9.26), and DRB1*1101 (8.02). In comparison with the control group, leprosy patients revealed a greater occurrence of the DRB1*1401 and DRB1*1406 alleles (P<0.002), for which they may be implied in leprosy susceptibility. By opposite, DRB1*0808 and DRB1*1103 alleles were less frequent among patients (P<0.002) and hence more involved in disease resistance. Conclusions: Molecular typing allowed the identification of increased frequencies of DRB1*1401 and DRB1*1406, in infected individuals respect to the seronegative controls, suggesting that these antigens could be related with the infection by M. leprae. In this patients also observed that the DRB1*0808 and DRB1*1103 alleles were statistically less frequent than in the group control. The HLA-DRB1 alleles could act alone or in combination with other genes to confer differential susceptibility and also protection to leprosy disease in endemic areas of the American continent.