A whole blood-based functional assay to characterize immunoglobulin A effector functions

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.

Keywords:

• Whole blood
• IgA subclasses
• IgA effector functions
• functional assay
• pre-clinical research
• flow cytometry
• inflammation

Author contributions

Conceptualization, A.B., C.C.G., R.E.M.T., and J.M.B.; Methodology, A.B., and C.C.G.; Formal Analysis, A.B., C.C.G., J.M.B.; Writing – Original Draft Preparation, A.B., C.C.G., J.M.B.; Writing – Review & Editing, R.E.M.T., K.A.v.S., J.M.B.

Conflicts of interest

C.C.G. and J.M.B. are current employees of Beckman Coulter Life Sciences. All other authors declare no conflict of interest.

Data availability statement

Raw data can be shared upon reasonable request.

Additional information

Funding

This work was supported by funding from the European Union’s Horizon 2020 Research and Innovation Program under Marie Sklodowska-Curie Grant Agreement 812890, ArthritisHeal.