Development of bone alkaline phosphatase-specific monoclonal antibodies and immunoassay exhibiting low cross-reactivity to liver isoform
Year: 2026
Type: article
Abstract: Tissue-nonspecific alkaline phosphatase (TNSALP) is an enzyme that catalyzes the hydrolysis of phosphomonoesters and promotes mineralization of bone. Tissue-nonspecific alkaline phosphatase contains 5 N-glycosylation sites: N140, N230, N271, N303, and N430. Bone alkaline phosphatase (BALP) and liver alkaline phosphatase (LALP) are isoforms of TNSALP. Despite sharing identical amino acid sequences derived from the single gene ALPL, these isoforms exhibit different glycosylation patterns. As osteoblasts express BALP, serum BALP levels reflect osteoblastic activity and are used as markers of bone formation. However, distinguishing serum BALP from coexisting LALP is challenging, as the 2 isoforms differ only in carbohydrate composition. Moreover, while BALP-specific immunoassays using BALP-selective mAbs are currently used in clinical laboratories, they exhibit significant cross-reactivity with LALP, highlighting the need for more selective assays for BALP. In the present study, we developed mAbs against BALP with minimal cross-reactivity to LALP. Using these mAbs, we generated an in-house BALP-specific immunoassay that exhibited high correlation with a clinically approved BALP test kit. Using a series of single N-glycosylation site mutants of TNSALP, we found that all 6 clones of BALP-selective mAbs recognized an epitope relevant to N303-linked glycans. These mAbs could facilitate the development of improved BALP assays with reduced cross-reactivity to LALP, enabling a more accurate diagnostic evaluation, particularly in patients with liver disease.
Source: JBMR Plus
Authors: Tatsuji Kimura, Shiomi Ojima, Kosuke Doi
Institution: Yamasa Corporation (Japan)
Language: English
Subfield: Endocrinology, Diabetes and Metabolism
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $2,888
OpenAlex ID: W7155797985