Which type of hypersensitivity is not antibody mediated?
a. Type I hypersensitivities
b. Type II hypersensitivities
c. Type III hypersensitivities
d. Type IV hypersensitivities
e. Antibodies mediate all of these.

Verified step by step guidance

1. Understand the four types of hypersensitivity reactions: Type I, II, III, and IV.
2. Recognize that Type I, II, and III hypersensitivities are mediated by antibodies.
3. Type I hypersensitivity involves IgE antibodies and is associated with allergic reactions.
4. Type II hypersensitivity involves IgG or IgM antibodies and targets cells for destruction.
5. Type III hypersensitivity involves immune complexes formed by IgG or IgM antibodies.
6. Identify that Type IV hypersensitivity is mediated by T cells, not antibodies.

Key Concepts

Hypersensitivity Types

Hypersensitivity reactions are classified into four types based on the immune mechanism involved. Type I (immediate) involves IgE antibodies, Type II (cytotoxic) involves IgG or IgM antibodies, and Type III (immune complex-mediated) also involves antibodies. Type IV (delayed-type) is mediated by T cells rather than antibodies, making it distinct from the other types.

Type IV Hypersensitivity

Type IV hypersensitivity, also known as delayed-type hypersensitivity, is primarily mediated by T lymphocytes and does not involve antibodies. This type of reaction typically occurs 24-48 hours after exposure to an antigen and is responsible for conditions such as contact dermatitis and graft-versus-host disease.

Antibody Mediation

Antibodies are proteins produced by B cells that play a crucial role in the immune response by identifying and neutralizing pathogens. In hypersensitivity reactions, antibody mediation is a key feature in Types I, II, and III, where antibodies trigger various immune responses. Understanding the role of antibodies helps differentiate between the types of hypersensitivity.