Contact dermatitis is -: (A) Type-I hypersensitivity, (B) Type-II hypersensitivity, (C) Type-III hypersensitivity, (D) Type-IV hypersensitivity
Answer is D. Contact dermatitis is a type IV hypersensitivity reaction. - delayed hypersensitivity sometimes results results from skin contact with a variety of chemicals - metals such as nickel and chromium, simple chemicals like dyes,drugs or plant allergens. The antigen activates specifically sensitised CD4 & CD8 T lymphocytes leading to the secretion of lymphokines and phagocyte accumulation. Reference : Anathanarayan & paniker's 9th edition, pg no: 162,167 <\p>