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A weak human MLR locus mapping at the right of a crossing-over between HLA-D, Bf and GLO
Abstract:
An unexpected MLR reaction has been observed between three HLA-identical sibs; it consists of bidirectional positive MLR between identical female twins and a sister. No argument for a lymphoid mosaic could be found, although twins were frequent in the family; similarly no HLA-A/B or HLA-B/D recombinant could be demonstrated. The MLR, although weak, was highly reproducible. PLTs could be raised between the sibs, without an apparent segregation in this family nor in five other families, but such PLTs discriminated well between the positive and negative controls. In the absence of any proof that such a weak MLR locus could be on another chromosome than chromosome 6, two lines of argument are indirect evidences that such a locus could be indeed on chromosome 6: one of the sibs differs from the two others for two markers outside HLA--D--DR--Bf: glyoxalate (GLO) and red blood group P.
Insights
An unexpected mixed lymphocyte reaction (MLR) occurred between identical twins and their sister. This study investigated the genetic basis of this weak, reproducible MLR, suggesting a potential locus on chromosome 6.
Area of Science:
- Immunogenetics
- Human Leukocyte Antigen (HLA) complex
- Mixed Lymphocyte Reaction (MLR)
Background:
- Identical twins and a sister exhibited an unexpected bidirectional mixed lymphocyte reaction (MLR).
- No evidence of lymphoid mosaicism or HLA recombination was found in the family.
- The observed MLR was weak yet highly reproducible.
Purpose of the Study:
- To investigate the genetic basis of an unusual mixed lymphocyte reaction (MLR) between HLA-identical siblings.
- To explore the potential location of a novel MLR locus, possibly outside the classical HLA region.
Main Methods:
- Performed mixed lymphocyte reactions (MLR) between HLA-identical siblings.
- Attempted to identify lymphoid mosaicism and HLA-A/B or HLA-B/D recombinants.
- Generated and tested proliferative lymphocyte T cultures (PLTs) for MLR.
- Analyzed genetic markers outside the HLA complex, including glyoxalate (GLO) and blood group P.
Main Results:
- A consistent, albeit weak, bidirectional MLR was observed between identical female twins and their sister.
- Proliferative lymphocyte cultures (PLTs) could be generated, demonstrating MLR but showing no clear segregation within the family or other families.
- Genetic analysis indicated one sibling differed in GLO and blood group P markers, suggesting linkage to chromosome 6.
Conclusions:
- The study identified an unexpected MLR between HLA-identical siblings, challenging existing understanding.
- While the exact locus remains unconfirmed, indirect evidence suggests a potential MLR locus on chromosome 6, distinct from known HLA genes.
- Further research is warranted to elucidate the genetic basis and implications of this novel MLR phenomenon.