Novel method for detection of Aβ and Iso-D7-Aβ N-terminus-specific B cells and Iso-D7-Aβ-specific antibodies

Alzheimer's disease (AD) is a multifactorial systemic disease that is triggered, at least in part, by the accumulation of β-amyloid (Aβ) peptides in the brain, but it also depends on immune system-mediated regulation. Recent studies suggest that B cells may play a role in AD development and point to the accumulation of clonally expanded B cells in AD patients. However, the specificity of the clonally expanded B cells is unknown, and the contribution of Aβ-specific B cells to AD pathology development is unclear. In this study, we have developed a novel method to identify Aβ-specific B cells by flow cytometry using fluorescent tetramers. The suggested method also enables the identification of B-cell clones specific to a more pathology-provoking form of Aβ with an isomerized Asp7 residue (Iso-D7-Aβ) that accumulates in elderly people and in AD patients. The method has been verified using mice immunized with antigens containing the isomerized or non-isomerized Aβ N-terminus peptides. In addition, we describe a new method for the detection of Iso-D7-Aβ-specific antibodies, which was tested on mouse serum. These methods are of potential importance in research aimed at studying AD and may be also utilized for diagnostic and therapeutic purposes.