DELAYED HYPERSENSITIVITY REACTIONS

Course overview

COOMBS AND GEL CLASSIFIED TYPE IV HYPERSENSITIVITY REACTION (HR) AS A DELAYED HYPERSENSITIVITY REACTION (DHR), WHICH TAKES MORE THAN 12 HOURS TO DEVELOP. TYPICALLY THE MAXIMAL REACTION TIME OCCURS BETWEEN 48 TO 72 HOURS. ANTIBODIES DO NOT MEDIATE DHR; IT IS MEDIATED BY T CELLS THAT CAUSE AN INFLAMMATORY REACTION TO EITHER EXOGENOUS OR AUTOANTIGENS. THIS HR TO EXOGENOUS ANTIGENS INVOLVES T CELLS AND ALSO ANTIGEN-PRESENTING CELLS (APC) SUCH AS MACROPHAGES AND DENDRITIC CELLS, ALL PRODUCE CYTOKINES THAT STIMULATE A LOCAL INFLAMMATORY RESPONSE IN A SENSITIZED INDIVIDUAL. THE DHR TO AUTOANTIGENS CAN BE SEEN IN TYPE 1 DIABETES MELLITUS, WHICH IS AN AUTOIMMUNE DISEASE THAT RESULTS FROM AUTOIMMUNE CELL-MEDIATED DESTRUCTION OF INSULIN-SECRETING PANCREATIC BETA CELLS. DHR CANNOT BE TRANSFERRED FROM AN ANIMAL TO ANOTHER BY MEANS OF ANTIBODIES OR SERUM. HOWEVER, IT CAN BE TRANSFERRED BY T CELLS, PARTICULARLY CD4 TH1 CELLS, BUT IT IS PROGRESSIVELY LOST IN INDIVIDUALS WITH HIV/AIDS. ANTIGEN-PRESENTING CELLS (APC) SUCH AS LANGERHANS CELLS ENGULF PROCESS AND PRESENT ANTIGENS TO ANTIGEN-SPECIFIC T CELLS THAT BECOME SENSITIZED. CYTOKINES PRODUCED BY KERATINOCYTES, APC, AND T CELLS RECRUIT ANTIGEN-NONSPECIFIC T CELLS AND MACROPHAGES TO PARTICIPATE IN A LOCAL INFLAMMATORY REACTION. THE ACTIVITY DESCRIBES THE INTERPROFESSIONAL EVALUATION AND MANAGEMENT OF PATIENTS WITH DELAYED HYPERSENSITIVITY REACTIONS.