Question:medium
Mixed lymphocyte culture is used to identify:
Mixed lymphocyte culture is used to identify:
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MLC proliferation is driven by CD4 helper T-cells reacting to an MHC class II mismatch.
Updated On: Jul 8, 2026
- MHC class I antigen
- MHC class II antigen
- B lymphocytes
- T helper cells
Show Solution
The Correct Option is B
Solution and Explanation
Step 1: Picture the actual experiment.
Take white blood cells from two different people and mix them in one dish. If their tissue types differ, something in the mix will react.
Step 2: Ask which tissue molecules trigger that reaction.
Helper T-cells (CD4 positive) are the ones that notice foreign HLA molecules on the other person's cells and respond by multiplying. CD4 cells are built to read MHC class II molecules specifically, not class I.
Step 3: Turn that reaction into a measurement.
More proliferation in the dish means the two people's MHC class II types (mostly HLA-DR) are more different from each other. Less proliferation means the class II types are closer to a match. This is exactly why the test is used before transplants, to gauge class II compatibility.
Step 4: Separate this from a class I test.
Testing MHC class I differences instead uses a cytotoxic T-lymphocyte assay, where CD8 cells kill mismatched target cells, a different setup from the proliferative mixed lymphocyte culture.
Step 5: Dismiss the cell-identity options.
B lymphocytes and T helper cells are both present and playing a role in the culture, but the test itself is not aimed at identifying either cell type, it is aimed at the MHC molecules driving the reaction.
Step 6: Conclude.
The mixed lymphocyte culture reads out MHC class II differences.
\[ \boxed{\text{MHC class II antigen}} \]
Take white blood cells from two different people and mix them in one dish. If their tissue types differ, something in the mix will react.
Step 2: Ask which tissue molecules trigger that reaction.
Helper T-cells (CD4 positive) are the ones that notice foreign HLA molecules on the other person's cells and respond by multiplying. CD4 cells are built to read MHC class II molecules specifically, not class I.
Step 3: Turn that reaction into a measurement.
More proliferation in the dish means the two people's MHC class II types (mostly HLA-DR) are more different from each other. Less proliferation means the class II types are closer to a match. This is exactly why the test is used before transplants, to gauge class II compatibility.
Step 4: Separate this from a class I test.
Testing MHC class I differences instead uses a cytotoxic T-lymphocyte assay, where CD8 cells kill mismatched target cells, a different setup from the proliferative mixed lymphocyte culture.
Step 5: Dismiss the cell-identity options.
B lymphocytes and T helper cells are both present and playing a role in the culture, but the test itself is not aimed at identifying either cell type, it is aimed at the MHC molecules driving the reaction.
Step 6: Conclude.
The mixed lymphocyte culture reads out MHC class II differences.
\[ \boxed{\text{MHC class II antigen}} \]
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