Preliminary Identification of Human Leukocyte Antigen (HLA) CLASS II DRB1 Allelic Variants in Selected Filipino Cancer Patient Samples
Objective. The Human Leukocyte Antigen (HLA) Class II is the major histocompatibility complex surface glycoproteins of humans responsible for presenting exogenous antigenic peptides which help direct specificity of immune response. In immune-cell therapy, the HLA allelic variants are of particular importance as they determine the successful activation of target cells that results to a desired therapeutic response. However, HLA Class II exhibits high polymorphism and has variable distribution in population, constituting these so-called allelic variants. Specifically, the HLA Class II DRB1 is considered the predominant locus among Filipinos. This research aimed to identify the presence of HLA Class II DRB1 allelic variants in the stem cell samples of ten (10) Filipino cancer patients by reverse transcription polymerase chain reaction (RT-PCR) amplification.
Method. This study employed a PCR-based HLA Class II typing to identify the HLA Class II DRB1 allelic variant in Filipino cancer patients. Design of forward and reverse primers for HLA Class II DRB1, optimization of PCR conditions for amplifying HLA Class II DRB1, and identification of HLA Class II DRB1 allelic variants from samples by sequencing and database comparison were conducted.
Results. PCR optimization showed that optimum annealing temperature for HLA DRB1 was 58.8°C with 1 mM MgCl2. PCR amplification of HLA DRB1 from ten anonymized cancer patient samples and DNA sequencing revealed that Patients 1, 2, 5, 8, 9, and 10 harbor HLA DRB1 allelic variants, particularly, the HLA DRB1*04:06:01, HLA DRB1*12:01:01, HLA DRB1*0813, HLA DRB1*04:05:01, HLA DRB1*09:01:02, and HLA DRB1*16:02:01, allelic variants, respectively.
Conclusion. Using the designed primers and optimized RT-PCR protocol, HLA information derived from six out of ten patient samples can be used for further applications in developing personalized or generic antigenic peptides such as dendritic cell cancer vaccine.