This is also known as immediate or anaphylactic-type reactions. This may be caused by foods, drugs, pollen, and/or insect stings.

This type of hypersensitivity involves specific antibodies called the Immunoglobulin G (IgG) and Immunoglobulin M (IgM). The antibody binds to and destroys the cell on which it is attached.

This type of reaction occurs after an organ transplant when the body refuses to see the transplanted organ as its own.

This is an Immune complex-mediated reaction. The immune complex is the bound form of an antibody and an antigen.

This sets off a chain reaction in the body, causing local tissues to be destroyed. Glomerulonephritis and systemic lupus erythematosus (lupus, SLE) are two examples of this disorder.

T-cell lymphocytes are special immune cells that mediate delayed or cell-mediated reactions. These T cells take from a few hours to a few days to mount an allergic response.

Examples include contact dermatitises such as poison ivy rashes.