Evidence for Prescribed NK Cell Ly-49 Developmental Pathways in Mice
Alberto J Millan1,2, Bryan A Hom1, Jeremy B Libang1
1Department of Molecular and Cell Biology, School of Natural Sciences, University of California, Merced, Merced, CA 95343.
Journal of Immunology (Baltimore, Md. : 1950)
|January 26, 2021
Summary
Natural killer (NK) cell receptor expression is not random. Activating and inhibitory Ly-49 receptor expression on NK cell clusters follows specific pathways during maturation.
Area of Science:
- Immunology
- Cell Biology
- Developmental Biology
Background:
- Natural killer (NK) cell receptor expression, particularly Ly-49 genes, was previously thought to be stochastic.
- Limited research has explored the mechanisms governing the acquisition of both activating and inhibitory Ly-49 receptors during NK cell development.
Purpose of the Study:
- To investigate whether the surface expression of activating Ly-49 receptors is nonrandom and influenced by inhibitory Ly-49 receptors.
- To analyze NK cell clusters based on the combinatorial expression of specific activating (Ly-49H, Ly-49D) and inhibitory (Ly-49I, Ly-49G2) receptors.
Main Methods:
- Analysis of NK cell clusters defined by Ly-49 receptor expression in C57BL/6 mice.
- Application of the product rule to assess interdependencies between Ly-49 receptors.
- In vitro culture and in vivo transplantation of sorted NK cell clusters.
- Assessment of cell proliferation using Ki-67 expression and cell counts.
Main Results:
- Evidence of tightly regulated Ly-49 receptor expression at the immature NK cell stage, with high interdependencies between clusters expressing activating receptors.
- Identification of predominant NK cell clusters at immature, transitional, and mature developmental stages.
- Demonstration of nonrandom Ly-49 receptor expression, suggesting defined pathways for NK cluster differentiation.
- Indication that Ly-49I surface expression is crucial for NK cell maturation.
- Confirmation that immature NK cells exhibit higher proliferation rates than mature NK cells.
- Observation that MHC class I plays a significant role in regulating Ly-49D and Ly-49G2, despite the absence of known ligands in B6 mice.
Conclusions:
- NK cell cluster differentiation follows prescribed pathways, with Ly-49 receptor expression being a nonrandom process.
- The surface expression of both activating and inhibitory Ly-49 receptors is correlated with NK cell maturation stages.
- MHC class I influences the regulation of specific Ly-49 receptors, highlighting complex regulatory mechanisms in NK cell biology.
