A whole blood-based functional assay to characterize immunoglobulin A effector functions
Alice Bacon1, Celia Cartagena García2, Karin A van Schie1
1Rheumatology Department, Leiden University Medical Center (LUMC), Leiden, The Netherlands.
Insights
Immunoglobulin A2 (IgA2) subclasses, IgA2m1 and IgA2m2, demonstrate a stronger pro-inflammatory immune cell activation compared to Immunoglobulin A1 (IgA1). This finding highlights IgA2
Area of Science:
- Immunology
- Molecular Biology
Background:
- Previous studies on immunoglobulin A (IgA) immune cell activation often used purified IgA or isolated cell types.
- IgA2 has been suggested to possess a more pro-inflammatory capacity than IgA1.
Purpose of the Study:
- To develop a rapid, whole blood assay for comparing the immune cell-activating potential of IgA1 and IgA2 subclasses under physiological conditions.
- To investigate the differential activation profiles of IgA1, IgA2m1, and IgA2m2 allotypes on various immune cell subsets.
Main Methods:
- Whole blood from healthy donors was stimulated with immobilized IgA1, IgA2m1, or IgA2m2.
- A 10-color flow cytometry panel was utilized to measure activation markers on major leukocyte subsets.
Main Results:
- IgA2m1 and IgA2m2 consistently induced stronger immune cell activation compared to IgA1 across multiple dimensions.
- Enhanced expression of CD54, CD11b, CD62L, CD66b, and CD69 was observed on monocytes and neutrophils stimulated with IgA2 allotypes.
- The study revealed donor-specific variations in immune responses.
Conclusions:
- IgA2 subclasses (IgA2m1 and IgA2m2) exhibit a more pronounced pro-inflammatory effect on immune cells than IgA1.
- The whole blood assay provides a valuable tool for studying IgA effector functions in mechanistic and translational research, considering donor variability.
Abstract:
Most investigations on the immune cell-activating potency of IgA used purified total IgA and/or specific isolated cell populations. As IgA2 has been reported to be more pro-inflammatory than IgA1, we aimed to employ a fast and convenient whole blood-based assay to individually probe the capacity of the two IgA subclasses to activate immune cells in close physiological conditions. To this end, whole blood from healthy donors (n = 10) was stimulated with immobilized IgA1, IgA2m1 or IgA2m2 (the two main allotypic variants of IgA2). Activation of major leukocyte subsets was measured using a 10-color flow cytometry panel providing access to the expression of 5 activation markers on 6 different immune cell subsets. While capturing some heterogeneity of responses among donors, IgA2m1 and IgA2m2 systematically showed a stronger activation profile compared to IgA1 in a variety of dimensions. For example, both IgA2 allotypes led to stronger modulations of CD54, CD11b, CD62L, CD66b or CD69, on both or either monocytes or neutrophils, indicating a more pronounced pro-inflammatory effect for this subclass than IgA1. By taking into account donor-specific soluble and cellular components this whole blood-based functional approach provides new perspectives to further investigate IgA effector functions in mechanistic studies and/or translational research.
