Each parent contributes how many MHC Class I gene variants to the offspring?

Immunologists classify antibodies into five major types in humans. Which of the following options is NOT included among those five immunoglobulin classes?

Type IV hypersensitivity is also known as:

A patient receives repeated booster injections of a protein vaccine. Several hours after one injection, a painful area of redness and swelling develops at the injection site. Examination shows deposition of antigen–antibody complexes in local blood vessels with complement activation. Which category of hypersensitivity best explains this reaction?

Which mediator is released during Type I hypersensitivity?

The effector cells in Type I hypersensitivity include: