Which of the following is considered a class I gene product?

To understand why HLA-A is considered a class I gene product, it's important to delve into the classification of human leukocyte antigens (HLA). HLA molecules are critical components of the immune system and are categorized into different classes based on their structure and function.

Class I HLA molecules are primarily involved in presenting endogenous antigens (from within the cell) to CD8+ T cells, which play a crucial role in the immune response against intracellular pathogens, such as viruses. Class I molecules are present on almost all nucleated cells in the body, facilitating the recognition of infected or abnormal cells by the immune system.

HLA-A is one of the key class I molecules and is involved in the presentation of peptide fragments derived from proteins synthesized within the cell. It helps the immune system identify and destroy cells that are infected or otherwise abnormal.

In contrast, HLA-DR and HLA-DQ are categorized as class II molecules. Class II molecules are primarily found on antigen-presenting cells (APCs) like dendritic cells, macrophages, and B cells. They present exogenous antigens (from outside the cell) to CD4+ helper T cells, which is vital for orchestrating the immune response.

HLA-DD does not