RT Book, Section
A1 Chandrasoma, Parakrama
A1 Taylor, Clive R.
SR Print(0)
ID 183917
T1 Chapter 8. Immunologic Injury
T2 Concise Pathology, 3e
YR 1998
FD 1998
PB The McGraw-Hill Companies
PP New York, NY
SN 9780838514993
LK accessphysiotherapy.mhmedical.com/content.aspx?aid=183917
RD 2021/02/27
AB Hypersensitivity  is  defined  as  an  abnormal,  exaggerated  immune  reaction  to  a  foreign  agent,  with  resulting  injury  to  host  tissues.  Four  different  mechanisms  of  hypersensitivity  have  been  elucidated  (Table  8-1).  All  forms  except  type  IV  are  mediated  by  humoral  mechanisms  (ie,  by  antibodies);  type  IV  hypersensitivity  is  cell-mediated.  In  all  forms,  initial  exposure  (sensitizing  dose)  to  the  antigen  involved  evokes  a  primary  immune  response  (sensitization).  Following  a  short  period  (1  or  more  weeks)  during  which  the  immune  system  is  activated,  a  hypersensitivity  response  occurs  upon  any  subsequent  exposure  (challenge  dose)  to  that  antigen.