During the physical examination of a 22-year-old man, a purified protein derivative isolated from Mycobacterium tuberculosis is injected into the skin. Three days later, the injection site appears raised and indurated. Which of the following glycoproteins was directly involved in antigen presentation during the initiation phase of delayed hypersensitivity in this patient?

Delayed-type hypersensitivity is defined as a tissue reaction involving lymphocytes and mononuclear phagocytes,which occurs in response to a soluble protein antigen and reaches greatest intensity 24 to 48 hours after initiation. In the initial phase, foreign protein antigens or chemical ligands interact with accessory cells bearing class II HLA molecules. Protein antigens are actively processed into sho peptides within phagolysosomes and are presented on the cell surface in conjunction with the class II HLA molecules. Diagnosis: Delayed-type hypersensitivity