Q.43 Match List I with List II
| LIST I CD antigen |
LIST II Expression on cells |
||
|---|---|---|---|
| A. | CD4 | I. | MHC class I-restricted T-cells |
| B. | CD8 | II. | MHC class II-restricted T-cells |
| C. | CD19 | III. | All leukocytes |
| D. | CD18 | IV. | B-cells |
Choose the correct answer from the options given below:
- A-I, B-III, C-IV, D-II
- A-II, B-I, C-IV, D-III
- A-II, B-IV, C-III, D-I
- A-IV, B-III, C-I, D-II
CD4, CD8, CD19, and CD18 have specific cell expression patterns: CD4 on MHC II-restricted T-cells, CD8 on MHC I-restricted, CD19 B-cell specific, CD18 all leukocytes.
The correct matching is A-II, B-I, C-IV, D-III, standard immunology classification for T/B cell markers and leukocyte integrins.
Question Breakdown
-
A. CD4: Helper T cells (MHC class II-restricted) – II
-
B. CD8: Cytotoxic T cells (MHC class I-restricted) – I
-
C. CD19: B lymphocyte lineage marker – IV
-
D. CD18: β2 integrin chain on all leukocytes (LFA-1, Mac-1) – III
Option Analysis
-
A-I, B-III, C-IV, D-II: Wrong (CD4 ≠ MHC I T-cells)
-
A-II, B-I, C-IV, D-III: Correct (standard immunology matching)
-
A-II, B-IV, C-III, D-I: Wrong (CD8 ≠ B-cells)
-
A-IV, B-III, C-I, D-II: Wrong (CD4 ≠ B-cells)
Correct Answer
A-II, B-I, C-IV, D-III
CD Antigen Classification
CD antigens define leukocyte subsets. CD4 marks helper T-cells recognizing MHC class II on APCs (macrophages, B-cells, dendritic). CD8 identifies cytotoxic T-cells binding MHC class I (all nucleated cells). CD19 pan-B cell marker from pro-B to plasma cells. CD18 (ITGB2) β-chain forms LFA-1/CD11a, Mac-1/CD11b on all leukocytes for adhesion/migration.
Correct Matching Explained
CD Antigen Cell Expression Function A. CD4 II. MHC class II-restricted T-cells Helper T (Th1/Th2/Th17/Treg) B. CD8 I. MHC class I-restricted T-cells Cytotoxic Tc/NK-like C. CD19 IV. B-cells BCR co-receptor signaling D. CD18 III. All leukocytes β2 integrin adhesion Why Other Options Fail
-
Option 1: CD4/CD8 reversed (basic T-cell biology error)
-
Option 3: CD8 on B-cells (impossible)
-
Option 4: CD4 on B-cells (confuses with CD19)
Exam Strategy
NEET/GATE golden rule: CD4 = Helper = MHC II; CD8 = Killer = MHC I. CD19 = B-cell throughout lineage. CD18 = universal leukocyte integrin (LAD deficiency = no CD18 = infections). Mnemonic: “4-2-help, 8-1-kill, 19-B, 18-all”.
Essential for your immunology and molecular biology exam prep.
-
