Which type of injury mediation is involved in Type IV hypersensitivity reactions?

Type IV hypersensitivity reactions are characterized primarily by the involvement of the immune system’s cellular components rather than antibodies. In this type of delayed hypersensitivity, the main mediators are cytokines and cytotoxic T cells.

Cytokines are signaling proteins that help to regulate the immune response, facilitating communication between immune cells. Cytotoxic T cells, on the other hand, are a type of T lymphocyte that directly attack and destroy infected cells or present antigens, contributing to tissue damage associated with this hypersensitivity.

This is distinct from other types of hypersensitivity reactions. For example, Type I hypersensitivity involves IgE antibodies and histamine release, while Type II and III rely more on antibody-mediated processes and complement activation. Thus, in Type IV hypersensitivity, the focus is on T cell-mediated immunity and the signaling pathways involved in inflammatory responses, rather than antibody action.