RESUMEN
Abstract: Background: Alopecia areata (AA) is a common disorder of unknown etiology that affects approximately 0.7% to 3.8% of patients among the general population. Currently, genetic and autoimmune factors are emphasized as etiopathogenic. Studies linking Human Leukocyte Antigens (HLA) to AA have suggested that immunogenetic factors may play a role in the disease's onset/development. Objectives: To investigate an association between AA and HLA class I/II in white Brazilians. Methods: Patients and control groups comprised 33 and 112 individuals, respectively. DNA extraction was performed by column method with BioPur kit. Allele's classification was undertaken using the PCR-SSO technique. HLA frequencies were obtained through direct counting and subjected to comparison by means of the chi-square test. Results: Most patients were aged over 16, with no familial history, and developed partial AA, with no recurrent episodes. Patients showed a higher frequency of HLA-B*40, HLA-B*45, HLA-B*53 and HLA-C*04 compared with controls, although P was not significant after Bonferroni correction. Regarding HLA class II, only HLA-DRB1*07 revealed statistical significance; nevertheless, it featured more prominently in controls than patients (P=0.04; Pc=0.52; OR=0.29; 95%; CI=0.07 to 1.25). P was not significant after Bonferroni correction. Conclusions: The development of AA does not seem to be associated with HLA in white Brazilians, nor with susceptibility or resistance. The studies were carried out in populations with little or no miscegenation, unlike the Brazilian population in general, which could explain the inconsistency found.
Asunto(s)
Humanos , Masculino , Femenino , Adolescente , Adulto , Persona de Mediana Edad , Adulto Joven , Antígenos de Histocompatibilidad Clase I/genética , Antígenos de Histocompatibilidad Clase II/genética , Brasil , Antígenos de Histocompatibilidad Clase I/sangre , Antígenos HLA-B/genética , Antígenos HLA-B/sangre , Antígenos HLA-C/genética , Antígenos HLA-C/sangre , Antígenos de Histocompatibilidad Clase II/sangre , Estudios de Casos y Controles , Estudios Transversales , Población Blanca , Alopecia Areata/genética , Alopecia Areata/inmunología , Cadenas HLA-DRB1/genética , Cadenas HLA-DRB1/sangre , Frecuencia de los Genes/genéticaRESUMEN
Fifty-seven sera obtained from pregnant women who attended antenatal clinic were screened for class I HLA antibodies by standard microlymphocytotoxicity test. The age ranged from 20 to 40 years (mean +/- SD = 30.4 +/- 5). The lymphocytes obtained from 98 HLA-typed persons were used as the panel which would include all common HLA-A and HLA-B antigens and as many rare antigens as possible. Eight out of 57 sera (14%) had HLA antibodies which reacted as follows: 3 sera had nonspecific antibodies, 3 sera had multispecific antibodies (B60 + B48 + B7, B60 + B61 + B13 and B51 + B35 + B53), one serum had a monospecific antibody (A2) and one serum was unidentified. The identified antibodies showed strong reactivity (r > 0.8). These sera will be used as HLA typing sera and exchanged with other HLA laboratories. The screening test for class I HLA antibodies in pregnant women attending the antenatal clinic is useful and practical. Several HLA antisera can be obtained at low cost. The cost of self-screening antisera was US$90/ml while the cost of commercial HLA typing sera is approximately US$250/ml, a factor to be considered by a new HLA laboratory with limited budget.