Affiliations 

  • 1 Universiti Putra Malaysia
  • 2 Universiti Kebangsaan Malaysia Medical Centre
MyJurnal

Abstract

Introduction: Human leukocyte antigens (HLA) are a group of unique transmembrane glycoproteins that are ex-pressed on the surface of virtually all types of cells within the human body. These molecules are encoded by a set of highly polymorphic gene sequences known also as the major histocompatibility complex (MHC) and play an essential role in the presentation of antigenic peptides to immune cells for recognition and response. In recent years, various HLA alleles have been found to be associated with different autoimmune and inflammatory diseases such as rheumatoid arthritis, systemic lupus erythematosus (SLE) and allergic rhinitis. Identification of these alleles via HLA typing is necessary for initial screening and diagnosis purposes. Besides that, HLA typing is also used to determine compatibility matching between a donor and a recipient for tissue/organ transplantations in order to prevent graft rejection. Therefore, good quality and quantity of genomic DNA is required. In most scenarios, peripheral blood is chosen as the most reliable source of DNA for analysis, however this approach is seen as invasive and may cause pain and anxiety among the patients, particularly young children and weak subjects. Hence, derivation of genomic DNA from buccal cells as an alternative source material is becoming increasingly popular, especially in PCR-based genetic assays. Some of the most commonly described methods to collect buccal cells include using oral swabs, cytological brushes, mouthwashes and treated cards. Each technique yields varying quantities of DNA with diverse purity levels. In this study, we aim to evaluate the amount and purity of genomic DNA extracted from buccal swabs and brushes as well as blood for screening of selected HLA class II alleles. Methods: Cheek cell samples were col-lected using sterile foam tipped buccal swabs (Whatman) and buccal collection brushes (Gentra Puregene) whereas peripheral blood samples were withdrawn following routine venipuncture techniques. All samples were subjected to DNA extraction according to modified commercial kit protocols. Screening of selected HLA-DRB1 alleles was con-ducted via PCR with sequence-specific primers as established by Bunce et al. 1995. Results: There was no significant difference (p > 0.05) in the total DNA yield obtained from blood and buccal swab samples, which were 17.57μg (± 8.66) and 13.28μg (± 4.81), respectively. All samples exhibited similar 260/280 ratios of about ~1.80 (p > 0.05). However, buccal brush samples contributed the least amount of DNA (0.29μg, ± 0.12) compared to other sources (p < 0.05). The pure genomic DNA isolated from both blood and buccal swab samples were successfully typed for low resolution HLA-DRB1 alleles. Conclusion: Buccal swabs provide good quantity and quality of DNA for screening of HLA alleles with high accuracy and thus can be utilized as a non-invasive substitute for venipuncture.