HLA-A Products

HLA-A is a critical member of the HLA class I molecule family, essential for the immune system's functioning. Each HLA-A molecule is a heterodimer, formed by a heavy chain paired with a beta-2 microglobulin light chain. The heavy chain, embedded in cell membranes, plays a pivotal role in immune defense by presenting peptides to cytotoxic T cells. This mechanism is crucial for the body's ability to recognize and respond to pathogens.

This molecule is ubiquitously expressed across almost all cell types. The heavy chain itself is about 45 kDa in size, encoded by a gene with 8 exons. These exons encode various components of the molecule, including the leader peptide, the peptide-binding alpha1 and alpha2 domains, the alpha3 domain, the transmembrane region, and the cytoplasmic tail. Notably, genetic variations in the peptide-binding domains (encoded by exon 2 and exon 3) confer the specificity of each HLA-A molecule, making them key in determining compatibility for bone marrow and kidney transplants.

HLA-A's significance extends to its role in infectious diseases. Variations in these molecules have been implicated in the progression and outcome of diseases caused by various pathogens, such as the malaria parasite, HIV, and coronaviruses including SARS-CoV and SARS-CoV-2. The latter, responsible for the COVID-19 pandemic, has multiple Class I epitopes that interact with HLA-A molecules, highlighting the importance of individual HLA genetic differences in immune responses across populations.