A boy has shortness of breath, presents in OPD; is injected with penicillin. He has never shown any history of allergy. On examination, after 48 hours, his RBC's are getting destroyed. He has been diagnosed with AIHA (Autoimmune hemolytic anaemia). Type of hypersensitivity is:
Type II or cytotoxic reaction is defined as reaction by humoral antibodies that attack cell surface antigens on the specific cells and tissues and cause lysis of target cells. 
Type II reaction too appears generally within 15-30 minutes after exposure to antigen.
 
EXAMPLES OF TYPE II REACTION
 
1. Cytotoxic antibodies to blood cells: 
i) Autoimmune haemolytic anaemia in which the red cell injury is brought about by auto-antibodies reacting with antigens present on red cell membrane. Antiglobulin test (direct Coombs’ test) is employed to detect the antibody on red cell surface.
ii) Transfusion reactions 
iii) Haemolytic disease of the newborn (erythroblastosis foetalis) 
iv) Idiopathic thrombocytopenic purpura (ITP)
v) Leucopenia with agranulocytosis
vi) Drug-induced cytotoxic antibodies
 
2. Cytotoxic antibodies to tissue components:
i) In Graves’ disease (primary hyperthyroidism) 
ii) In myasthenia gravis
iii) In male sterility
iv) In type 1 diabetes mellitus
v) In hyperacute rejection reaction
 
Mohan H. Textbook of pathology. Jaypee Brothers Medical Publishers; 2015. Edition 7. Page 60
Type I
Type II
Type III
Type IV