Question

MHC detection by mixed leukocyte reaction

Answer 1

The mixed lymphocyte reaction (MLR) is designed for typing MHC class II molecules on the surface of lymphocytes for the purpose of tissue transplantation. In this assay, typing cells with known MHC specificities are rendered metabolically paralyzed and then are mixed with the patient's cells.

If however it sees foreign determinants, then it will react with blastogenesis. Blastogenesis can be measured by incorporation of radioactive nucleotides. MLR have been used to assist in characterization of MHC class II specificities in several species. If the patient shares specificities with the typing cells, it will not react.

Principle:

1. When you mix lymphocytes of two people together, each cell population will recognize any foreign HLA Class 2 (D) antigens of the other.

2. Lymphocytes will respond by blast transformation and synthesizing new DNA

3. Radio labeled thymidine ([³H] thymidine) is added to culture and will be incorporated into the new DNA

4. The uptake of thymidine is measured and tells us the difference between the HLA Class 2 types of the person (↑ thymidine uptake = ↑ DNA created = ↑ difference in HLA types of the two people)

5. Thymidine uptake is quantitated in a liquid scintillation device

6. A low MLC is associated with excellent transplant survival

Duration and when to use it:

It takes 4 - 5 days to perform and is used only for living donors because organs from deceased donors only survive 24 to 48 hours.