Question

Arrange the following statements in sequential order regarding hypersensitivity reaction IV.
a) Haptens combine with skin proteins to form the haptens-protein carrier.
b) Antigen presenting cells present the hapten-carrier complex to the T-cells.
c) T cells recognise the hapten-carrier complex and release lymphokines or interleukins.
d) Antigen presenting cells APC carry this hapten-carrier complex to the lymphatics.

• A. a, d, b, c
• B. b, d, c, a
• C. c, d, b, a
• D. None of the above

Answer 1

The correct option is A a, d, b, c

A- Type IV hypersensitivity reaction also known as delayed type hypersensitivity( DTH ). It is a cell mediated immune reaction and doesn't involve antibody participation but is due to interaction of T cells with antigens. When a sub population of activated helper T cell encounter certain antigens secrete cytokines that induces DTH which is characterized by influx of non specific inflammatory cells particularly macrophages. DTH occurs slowly and reaches peak levels within 48-72 hours after the 2nd encounter of antigens.