Which type of hypersensitivity reaction is T cell mediated and involves lymphokine release?

The correct choice is associated with delayed-type hypersensitivity, which is primarily mediated by T cells. This type of reaction occurs when T lymphocytes (specifically CD4+ helper T cells and CD8+ cytotoxic T cells) become activated in response to an antigen. In doing so, they release various cytokines and lymphokines that orchestrate the immune response.

Type IV hypersensitivity does not involve antibodies but rather an immune response where T cells recognize and respond to specific antigens. This can lead to a variety of tissue reactions, which manifest as inflammation and often result in delayed responses, taking hours to days to develop after exposure to the antigen. Classic examples of Type IV hypersensitivity include contact dermatitis (such as from poison ivy), tuberculin skin tests, and graft-versus-host disease.

In contrast, other types of hypersensitivity reactions involve different immune mechanisms. For example, Type I hypersensitivity is IgE-mediated and involves immediate reactions, while Type II and Type III are mediated by antibodies (IgG or IgM) and involve tissue damage through complement activation and immune complex formation, respectively. Thus, the distinctive feature of Type IV hypersensitivity is its dependence on T cell activity and lymphokine release, leading to specific immune responses