A convenient method for measuring immune complexes between tissue-nonspecific alkaline phosphatase (TNSALP) and immunoglobulin G (IgG) (i.e., TNSALP-IgG) would be highly useful for routine analyses. Here, we identified a surface-active agent that would dissolve membrane but not dissociate TNSALP-IgG complexes. Next, we developed an enzyme-linked immunosorbent assay (ELISA) method for detecting TNSALP-IgG complexes with two monoclonal antibodies (MoAbs): 3-29-3R was coated on assay plates and captured TNSALP-IgG from a specimen; an horseradish peroxidase (HRP)-conjugated anti-human IgG1 then reacted with captured TNSALP-IgG to form an "immunocomplex sandwich." The immunocomplex was detected via the absorbance of an HRP substrate, resulting in a semiquantitative assay. The mean absorbance of 0.195 (n=5) measured in sera from healthy donors was designated as an arbitrary unit (AU/mL) of TNSALP-IgG concentration. The ELISA values of patient sera known to contain TNSALP-IgG complexes were greater than those of normal sera (normal, 1.86 plusmn; 0.61; patient, 9.30 plusmn; 5.44), and these data were confirmed by electrophoresis. Thus, the ELISA could detect TNSALP-IgG complexes. The intraassay coefficient of variation (CV) was within 7.4% and analytical recovery was excellent. There was no significant interference from hemolytic, lipemic, or icteric serum. In summary, an ELISA using 3-29-3R MoAb and HRP-conjugated anti-human IgG1 constitutes a reliable and convenient method for the semiquantitative detection of TNSALP-IgG complexes in human serum.

Serum band 5 tartrate-resistant acid phosphatase (TRACP 5; EC 3.1.3.2) is a glycoprotein that exists as two very similar isoforms, TRACP 5a and TRACP 5b. The similarity of these two isoforms has made it difficult to establish monoclonal antibodies specific for either isoform. We report here the development of a monoclonal antibody with high specificity for TRACP 5b. We prepared TRACP 5b antigens from four sources: TRACP 5b purified from human bone, recombinant TRACP 5 from Escherichia coli, recombinant TRACP 5 from insect cells, and a synthetic TRACP 5b peptide. Thirty-seven mice were each immunized with 1 of the 4 different TRACP antigens to generate 473 antibody-producing clones. Three of these clones, Trk27, Trk49, and Trk62, reacted with TRACP 5b. These three clones were all established from mice exposed to native bone TRACP 5b antigen. In fact, none of the other antigens were able to generate anti-TRACP 5b monoclonal antibodies in mice. Furthermore, Trk62 interacted more strongly with TRACP 5b than with TRACP 5a. These results suggested that although recombinant proteins can be effective antigens, the native TRACP 5 protein might be more effective at generating monoclonal antibodies of greater specificity due to its more faithful representation of the native three-dimensional structure of the protein.

Tissue-nonspecific alkaline phosphatase (TNSALP) in serum comprises liver alkaline phosphatase (liver-ALP) and bone alkaline phosphatase (bone-ALP). Liver-ALP is a marker of liver disease; thus a specific method for its measurement would be useful. Measurement of ALP by electrophoresis is difficult, although all of the isozymes can be assessed simultaneously. Total ALP can also be measured by automated analyzer, but it is difficult to determine the cause of a high ALP value because bone-, intestine-, placenta-, and tumor-ALP are measured together. Thus, anti-TNSALP monoclonal antibodies that can resolve these problems are needed. Here we have generated an anti-TNSALP monoclonal antibody, 3-29-3R. This clone has specificity to liver-ALP rather than to bone-ALP. In electrophoresis, 3-29-3R reacted with TNSALP and shifted the bands. The use of 3-29-3R enabled easy interpretation of the results. Furthermore, we tested 3-29-3R by developing an immunocapture enzymatic assay (IEA). Preliminary results of the IEA show that this method is effective for measurement of liver-ALP. Thus, the monoclonal antibody that we have established may be a useful tool for clinical diagnosis.

Background: Chlorophosphonazo-III (2,7-bis[4-chloro-2-phosphonophenylazo]-1,8-dihydroxy-3,6-naphthalenedisulphonic acid, disodium salt; CPZ-III) reacts with calcium and magnesium in a sample under acidic to neutral conditions. However, the specific method of measuring calcium in serum using CPZ-III has not been established because of the difficulty of avoiding the interaction between CPZ-III and albumin. Methods: In this study, we found that the non-specific reaction between CPZ-III and albumin could be controlled and calcium in serum could be specifically detected using CPZ-III combined with vanadate. On the basis of this finding, we evaluated a novel method of serum calcium determination using CPZ-III.