Impact of antibody specificity and calibration material on the measure of agreement between methods for cardiac troponin I.

Background: Available assays for cardiac troponin I (cTnI) yield numerically different results. The aim of this study was to compare patient values obtained from four cTnI immunoassays.

Methods: We studied the Stratus(R) II assay, the Opus(R) II assay, the Access(R) assay, and a research-only cTnI heterogeneous immunoassay that uses the Dade Behring aca(R) plus immunoassay system equipped with two new noncommercial monoclonal antibodies.

Molecular mass determination for prostate-specific antigen and alpha 1-antichymotrypsin complexed in vitro.

The results from molecular mass determinations and amino acid analyses for prostate-specific antigen (PSA), alpha 1-antichymotrypsin (ACT) and PSA-ACT complexed in vitro are reported. Molecular masses for two separate PSA-ACT lots were determined by matrix-assisted laser desorption ionization mass spectroscopy (MALDI-MS) coupled to a time-of-flight (TOF) detector. Interestingly, both PSA-ACT lots contained two predominant protein species: 78,095 +/- 138 Da (approx.

Development and validation of an automated latex-enhanced immunoassay for prealbumin.

The measurement of circulating prealbumin has been shown to be clinically useful in the assessment of nutritional status, both as an initial screen and in the monitoring of nutritional recovery. We describe a fully automated, noncompetitive, homogeneous, light-scattering immunoassay that has been developed for this analyte on a Dimension (Dade) analyzer. A sheep anti-prealbumin IgG fraction was covalently coupled to 40-nm chloromethyl styrene particles and, after the addition of sample, polyethylene glycol-assisted immunoagglutination was monitored by turbidimetry.

Molecular targets of CD45 in B cell antigen receptor signal transduction.

Expression of the phosphotyrosine phosphatase CD45 is essential for B cell Ag receptor (BCR)-mediated p21ras activation and calcium mobilization. To examine the molecular basis of this requirement, we analyzed signaling events following BCR ligation in CD45-deficient (CD45-) and CD45-reconstituted (CD45+) variants of J558Lmicrom3 cells. Ag stimulation resulted in tyrosine phosphorylation of cellular proteins in both cells.

Manipulation of B cell antigen receptor tyrosine phosphorylation using aluminum fluoride and sodium orthovanadate.

The B cell antigen receptor complex (BCR) is composed of a membrane-spanning immunoglobulin molecule (mIg) non-covalently associated with heterodimers of the transmembrane proteins Ig-alpha and Ig-beta. The cytoplasmic domains of Ig-alpha and Ig-beta do not contain kinase domains but are phosphorylated on tyrosine residues immediately upon receptor ligation. The mechanism and kinase responsible for initial Ig-alpha and Ig-beta phosphorylation following receptor ligation is unknown, In an attempt to better understand this process, Ig-alpha and Ig-beta phosphorylation was examined in response to treatment of permeabilized B cells with the pharmacologic agents, aluminum fluoride (AlFx) and sodium orthovanadate (Na3VO4).

Distinct p53/56lyn and p59fyn domains associate with nonphosphorylated and phosphorylated Ig-alpha.

Among the earliest detectable events in B-cell antigen receptor-mediated signal transduction are the activation of receptor-associated Src-family tyrosine kinases and the tyrosine phosphorylation of Ig-alpha and Ig-beta receptor subunits. These kinases appear to interact with resting B-cell antigen receptor complexes primarily through the Ig-alpha chain antigen receptor homology 1 (ARH1) motif. Recent studies showed a dramatic increase in the amount of Src-family kinase p59fyn bound to Ig-alpha when ARH1 motif tyrosines were phosphorylated.

Conversion of an anti-single-stranded DNA active site to an anti-fluorescein active site through heavy chain complementarity determining region transplantation.

Complementarity determining region (CDR) transplant studies were conducted between two monoclonal antibodies of distinctly different specificities (anti-fluorescein monoclonal antibody (mAb) 4-4-20 and anti-single-stranded DNA (ssDNA) mAb 04-01) which possessed nearly identical light chains but dissimilar heavy chains. The variations in binding specificities between the two immunoglobulins suggested that the active-site features of anti-fluorescein antibodies were dictated by characteristics intrinsic to the heavy chain (H-chain). To identify specific regions of the H-chain which influence the structure and function of an anti-fluorescein active site, CDR transplantation was systematically employed to convert the anti-ssDNA 04-01 antibody active site to an active site with anti-fluorescein activity.

Relative binding properties of fluorescein and 9-hydroxyphenylfluoron (HPF) with murine monoclonal anti-fluorescein antibodies.

Contribution of the fluorescein (F1) carboxyl group to hapten binding by idiotypically related murine monoclonal anti-F1 antibodies 4-4-20, 9-40 and 12-40 was studied by comparing relative liganded active site properties with bound Fl or 9-hydroxyphenylfluoron (HPF). Kinetic studies revealed similar association rate constants between Fl and HPF to 4-4-20 (approximately 1.1 x 10(7) M-1 s-1); however, the 4-4-20 dissociation rate for Fl was approximately 200 times slower, relative to HPF, which resulted in relative intrinsic affinity values of 1.

Autologous anti-metatype immune response in rabbits.

Rabbits hyperimmunized with fluorescyl-conjugated KLH exhibited bound ligand associated with a high affinity circulating IgG anti-fluorescein population. After cessation of immunogen administration the liganded complexes were eventually spontaneously cleared from the circulation. Individual rabbits synthesized autologous anti-metatype antibodies specific for ligand-antibody complexes.

Single chain antibody (SCA) encoding genes: one-step construction and expression in eukaryotic cells.

We report the expression, in eukaryotic cells, of a gene encoding a single chain antibody (SCA) and a rapid method for the construction of such genes. A SCA directed against the aromatic dye fluorescein was synthesized from a gene constructed by means of the simultaneous use of four PCR primers and templates of both light and heavy chain immunoglobulin cDNAs in the form of either plasmid clones or reverse transcribed hybridoma RNA. Two of the primers were partially complementary to one another and encoded the polypeptide linker which joins the immunoglobulin light and heavy chain variable domains of the SCA polypeptide.

Active site contributions to fluorescein binding determined by in vitro heavy and light chain reassociations.

In addition to prior crystallographic studies that determined antigen contact residues for high affinity murine monoclonal anti-fluorescein (Fl) antibody 4-4-20 (Ka = 1.7 x 10(10) M-1), primary structure comparisons revealed idiotypically cross-reactive monoclonal anti-Fl antibody 9-40 (Ka = 5.7 x 10(7) M-1) possessed identical Fl contact residues with the exception of L34 His for Arg.

Immunological and structural characterization of a high affinity anti-fluorescein single-chain antibody.

Single-chain antibody of the (NH2) VL-linker-VH (COOH) design, was constructed based on prototype high affinity anti-fluorescein monoclonal antibody (mAb) 4-4-20. Purified single-chain antibody (SCA) 4-4-20/212 was studied relative to Ig mAb 4-4-20 in terms of ligand binding, kinetics, idiotypy, metatypy, and stability in denaturing agents. Ligand-binding data correlated with metatypic relatedness of the liganded site.

Active site structure and antigen binding properties of idiotypically cross-reactive anti-fluorescein monoclonal antibodies.

This report includes complete VH and V kappa nucleotide and deduced amino acid sequences of idiotypically cross-reactive monoclonal anti-fluorescein antibodies that differed greater than 10(5)-fold in affinity. High affinity monoclonal antibody 4-4-20 and intermediate affinity antibodies 10-25, 5-14, 9-40, 12-40, and 3-24 utilized greater than or equal to 90% homologous VHIIIC germ-line genes. Extensive D segment length and sequence variability were observed; however, compensatory germ-line JH4 (4-4-20 and 3-24) or JH3 (10-25, 5-14, 9-40, and 12-40) sequence lengths resulted in H chain CDR3 + FR4 to be a constant 18 amino acids.

Variable region primary structures of a high affinity anti-fluorescein immunoglobulin M cryoglobulin exhibiting oxazolone cross-reactivity.

Previous studies of murine IgM hybridoma protein 18-2-3, derived from an (NZB/NZW)F1 mouse following hyperimmunization with fluorescein (Fl)-conjugated keyhole limpet hemocyanin, demonstrated a high affinity for Fl (Ka = 2.9 x 10(10) M-1) and cryoprecipitation that was abrogated upon Fl binding to the antibody-combining site. V region sequences of 18-2-3 were determined by Edman degradation and nucleotide sequence analysis.

Comparison of variable region primary structures within an anti-fluorescein idiotype family.

Previous reports described the properties of a high affinity (Ka = 1.7 X 10(10) M-1) prototype anti-fluorescein monoclonal antibody 4-4-20, an intermediate affinity (Ka = 3.7 X 10(7) M-1) prototype 9-40, and Ig members of the 9-40 idiotype family (comprised of 3-24, 5-14, 5-27, 10-25 and 12-40).

Linkage of low and high affinity anti-fluorescein idiotype families.

Data presented in this study describes the isolation and characterization of two anti-fluorescein (F1) hybridoma proteins 3-24 and 12-40, both IgG1, kappa with a Ka = 2.8 and 3.4 X 10(6) M-1, respectively, at 37 degrees C.