In the mixed lymphocyte reaction (MLR) used to assess HLA matching for transplantation, the ONE-WAY MLR is performed by irradiating stimulator cells. What is the specific purpose of irradiating the stimulator lymphocytes?

• A To prevent stimulator cells from releasing cytokines
• B To upregulate MHC class II expression on stimulator cells
• C To inactivate NK cells present in the stimulator population
• D To prevent stimulator cells from proliferating and confounding the responder cell count ✓

Explanation

Irradiation (or mitomycin-C treatment) prevents stimulator cell proliferation so that only responder-cell DNA synthesis (measured by thymidine incorporation) reflects alloreactivity. If both populations could divide, it would be impossible to attribute proliferation to the responder alone, defeating the one-way assay design.

Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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