Which cell type expresses HLA class II antigens and is commonly used to phenotype HLA class II status?

Which cell type expresses HLA class II antigens and is commonly used to phenotype HLA class II status?

• A. T lymphocytes
• B. B lymphocytes
• C. NK cells
• D. Monocytes

Answer: (B)

HLA class II antigens are expressed mainly on professional antigen-presenting cells to present extracellular peptides to CD4+ T helper cells. For phenotyping HLA class II status, you want a cell type that reliably shows surface HLA class II. B lymphocytes fit this best because they constitutively express high levels of HLA class II and are easy to isolate from blood, providing a strong, consistent signal. In contrast, resting T lymphocytes and NK cells typically do not express HLA class II, while monocytes do express it but are less convenient for routine phenotyping. Therefore, B lymphocytes are the best choice for this purpose.

HLA class II antigens are expressed mainly on professional antigen-presenting cells to present extracellular peptides to CD4+ T helper cells. For phenotyping HLA class II status, you want a cell type that reliably shows surface HLA class II. B lymphocytes fit this best because they constitutively express high levels of HLA class II and are easy to isolate from blood, providing a strong, consistent signal. In contrast, resting T lymphocytes and NK cells typically do not express HLA class II, while monocytes do express it but are less convenient for routine phenotyping. Therefore, B lymphocytes are the best choice for this purpose.