Q.40 Match hypersensitivity types in Group I with their corresponding condition
in Group II.
Group I                     Group II
P. Type I                   1. Erythroblastosis fetalis
Q. Type II                 2. Host reaction to bee venom
R. Type III                3. Systemic lupus erythematosus
S. Type IV                 4. Tuberculin reaction
(A) P-2, Q-3, R-1, S-4
(B) P-3, Q-1, R-4, S-2
(C) P-2, Q-3, R-4, S-1
(D) P-2, Q-1, R-3, S-4

Hypersensitivity reactions represent exaggerated immune responses classified into four types by Gell and Coombs. This guide decodes a key MCQ matching Type I-IV with conditions like bee venom reaction and tuberculin test.

Correct Answer

The correct matching is (D) P-2, Q-1, R-3, S-4. Type I (P) links to host reaction to bee venom (2), Type II (Q) to erythroblastosis fetalis (1), Type III (R) to systemic lupus erythematosus (3), and Type IV (S) to tuberculin reaction (4).

Type I Hypersensitivity (P-2)

Type I involves IgE-mediated immediate reactions where allergens trigger mast cell degranulation, releasing histamine. Bee venom exemplifies this through anaphylaxis or localized swelling upon re-exposure. Common in allergies like asthma or urticaria.

Type II Hypersensitivity (Q-1)

Type II features IgG/IgM antibodies targeting cell surfaces, causing cytotoxicity via complement or phagocytosis. Erythroblastosis fetalis (hemolytic disease of the newborn) occurs when maternal Rh antibodies attack fetal Rh+ red blood cells. Other examples include autoimmune hemolytic anemia.

Type III Hypersensitivity (R-3)

Type III arises from immune complex deposition activating complement, leading to inflammation. Systemic lupus erythematosus (SLE) involves anti-nuclear antibodies forming complexes in tissues like kidneys and skin. Serum sickness shares this mechanism.

Type IV Hypersensitivity (S-4)

Type IV is delayed, T-cell mediated without antibodies, peaking in 48-72 hours. Tuberculin reaction (Mantoux test) shows induration from sensitized T cells releasing cytokines against Mycobacterium tuberculosis antigens. Includes contact dermatitis and graft rejection.

Why Other Options Fail

• (A) P-2, Q-3, R-1, S-4: Wrongly assigns Type II to SLE (Type III) and Type III to erythroblastosis (Type II).

• (B) P-3, Q-1, R-4, S-2: Misplaces Type I to SLE and Type IV to bee venom.

• (C) P-2, Q-3, R-4, S-1: Confuses Type II with SLE and Type IV with erythroblastosis.