Final answer:
Therefore, the correct answer to the student's question is c. TH1; usually survive.
Tuberculoid leprosy is characterized by a TH1-type immune response where patients usually survive because it involves an effective immune system able to contain the infection with Mycobacterium leprae, which is the causative agent identified in a skin biopsy for this disease.
Step-by-step explanation:
Tuberculoid leprosy is characterized by a TH1-type response in which patients usually survive. This form of leprosy involves an effective immune response including cell-mediated cytotoxicity, where the infection with Mycobacterium leprae is contained by a robust TH1-mediated immune system. Macrophages activated by TH1 cells are better suited to destroy intracellular bacteria. If diagnosis of tuberculoid leprosy is correct, Mycobacterium leprae would be found in a skin biopsy of the affected area. This mycobacterium species causes leprosy, is slow-growing, aerobic, resistant to drying and phagocytosis, and is covered with a waxy coat made of mycolic acid.
An effective TH1 response limits the spread of the infection and usually prevents progression to the more severe lepromatous leprosy. The engagement of TH1 cells and macrophages characterizes the cellular response needed to control the infection. This contrasts with TH2 responses, which are primarily directed toward extracellular pathogens and involve B-cell activation and antibody production.