Introduction

INTRODUCTION- TYPE IV HYPERSENSITIVITY

  • Delayed Type Hypersensitivity (DTH) reactions are classified as Type IV hypersensitivity and results from interaction between the injected antigen, antigen presenting cells and T cells (cell mediated).
  • These reactions is not induced by circulating bodies but by the sensitized T cells which on contact with specific antigen release lymphokines and exert biological effects on lymphocytes, inflammatory cells and tissue cells.
  • DTH can not be passively transfer by serum but can be done with lymphocytes. Two types of DTH are recognized (i) Tuberculin (injection) type and (ii) contact dermatitis type.
  • Example: Tuberculin reaction – the skin reaction in an animal that results from an intradermal injection of tuberculin which is an antigenic extract from the tubercle bacillus.
Last modified: Thursday, 26 August 2010, 9:39 AM