Which of the following principally mediates delayed type hypersensitivity?

Cytotoxic T lymphocytes, helper T1 lymphocytes, and macrophages mediate the delayed-type hypersensitivity reaction, which develops in response to viral, fungal, and intracellular bacterial antigens. Antibodies do not play a significant role in this type of response. IgE, basophils, and mast cells are involved in the production of type I hypersensitivity. IgG and complement is a mechanism of toxicity in type II cytotoxic hypersensitivity. IgG, IgM, neutrophils, and macrophages may be involved in types II or III hypersensitivities. Ref: Levinson W. (2012). Chapter 65. Hypersensitivity (Allergy). In W. Levinson (Ed), Review of Medical Microbiology & Immunology, 12e.