Cytotoxic Hypersensitivity Type II Type II Cytotoxic hypersensitivity

Type II Cytotoxic hypersensitivity Reaction time is minutes to hours n mediated by antibodies

Some diseases caused by Type II n n n Transfusion reactions Autoimmune Hemolytic anemia

Drug-Induced Reactions: Adherence to Blood Components blood cell adsorbed drug or antigen drug metabolite

Drugs that can cause this type of hemolytic anemia include: n n n Cephalosporins

Hemolytic Disease of the Newborn first birth post partum subsequent Rh. D negative mother

Type III (Immune complex mediated Diseases) The reaction may be general (e. g. ,

Tissue injury mechanisms n Antibodies may opsonize cells or activate the complement system Production

Some diseases caused by immune complexes Systemic Lupus Erythematosus n Nephritis n Vasculitis n

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Cytotoxic Hypersensitivity (Type II)

Type II Cytotoxic hypersensitivity Reaction time is minutes to hours n mediated by antibodies of Ig. M or Ig. G class and complement n Phagocytes and NK cells may also play a role (ADCC). n Diagnostic tests include detection of circulating antibody against tissues involved and the presence of antibody and complement in the lesion (biopsy) by immunofluorescence n n Directed against cell surface or tissue antigen The reaction may be local

Some diseases caused by Type II n n n Transfusion reactions Autoimmune Hemolytic anemia Hemolytic disease of newborn Drug induced hemolytic anemia Autoimmune thrombocytopenia Pemphigus vulgaris(desmoglein ) Goodpastures syndrome Myasthenia gravis Graves disease Insulin resistant diabetes Pernicious anemia others

Drug-Induced Reactions: Adherence to Blood Components blood cell adsorbed drug or antigen drug metabolite antibody to drug complement lysis

Drugs that can cause this type of hemolytic anemia include: n n n Cephalosporins (a class of antibiotics) Levodopa Methyldopa Penicillin and its derivatives Quinidine Some nonsteroidal anti-inflammatory drugs (NSAIDs)

Hemolytic Disease of the Newborn first birth post partum subsequent Rh. D negative mother Rh. D positive red cells Rh. D positive fetus B cell anti-Rh. D Lysis Of RBC’s Rh. D positive fetus

Type III (Immune complex mediated Diseases) The reaction may be general (e. g. , serum sickness) or may involve individual organs including skin ( Arthus reaction), kidneys, lungs, blood vessels , joints or other organs. n It is mediated by soluble immune complexes n The reaction may take few hours after exposure to the antigen n The lesion contains primarily neutrophils n

Tissue injury mechanisms n Antibodies may opsonize cells or activate the complement system Production of complement proteins that opsonize cells. These cells are phagocytosed and destroyed by phagocytes that express Fc. R and CR Main mechanism in autoimmune hemolytic anemia and thrombocytopenia and hemolysis in transfusion reactions.