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Atopic asthma: differential activation phenotypes among memory T helper cells
M L Lara-Marquez1, M J Moan, S Cartwright
1Respiratory Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
Summary
Activated memory T helper cells, specifically those expressing IL-2 receptor (IL-2R) and MHC class II (MHC II), are key in atopic asthma. Asthmatics show a distinct increase in double-positive IL-2R+MHC II+ memory T helper cells compared to non-asthmatics.
Area of Science:
- Immunology
- Cell Biology
- Respiratory Medicine
Background:
- T cells play a role in atopic asthma pathogenesis.
- Memory T helper cells (CD4+CD45RO+) are activated more than naive T helper cells (CD4+CD45RA+) after allergen challenge.
- Specific activated T helper subpopulations in atopy and asthma remain undefined.
Purpose of the Study:
- Identify T helper subpopulations and activation phenotypes in acute and stable asthma.
- Determine if these phenotypes are common to or distinct from atopy.
Main Methods:
- Analyzed peripheral blood from atopic asthmatics (acute and stable), non-asthmatic atopics, and normal controls.
- Used multicolor flow cytometry to assess T cell subpopulations.
- Measured expression of IL-2 receptor (IL-2R) and MHC class II (MHC II) on naive and memory T helper cells.
Main Results:
- Atopic asthmatics showed increased memory T helper cells expressing IL-2R and MHC II compared to normal non-atopics.
- Naïve T helper cells had low IL-2R and MHC II expression across all groups.
- Asthmatics had a higher proportion of double-positive (IL-2R+MHC II+) memory T helper cells compared to non-asthmatic groups.
Conclusions:
- Identified three subsets of activated memory T helper cells in asthmatics: IL-2R+, MHC II+, and double-positive (IL-2R+MHC II+).
- The double-positive subset is significantly elevated in asthmatics (acute or stable).
- This suggests a specific T helper activation phenotype distinguishing atopic asthmatics from atopic non-asthmatics.