SummaryA new highly sensitive sandwich ELISA assay was developed for the determination of plasma factor XIII (FXIII). Plasma FXIII is a tetrameric complex of two types of subunits (A2B2). A biotinylated monoclonal capture-antibody against the B-subunit and a peroxidase-labelled monoclonal tag-antibody against the A-subunit were added to the plasma dilution and the amount of the complex attached to streptavidincoated microplate was quantitated by measuring peroxidase activity. Only the tetrameric plasma FXIII reacted in the assay, non-complexed A or B subunits showed no reaction. The assay is linear up-to 40 µg/L of FXIII in the assay mixture. It is a quick one-step assay which can be performed within two hours. At normal and low FXIII concentration within batch reproducibility was 2.0% and 3.3%, day to day variation was 5.5% and 8.7%, respectively. Its high sensitivity allows reliable measurement at FXIII concentrations below 1% of normal average. Plasma samples can be stored for the assay at –20° C for at least one month. Plasma levels of healthy individuals were normally distributed and no gender difference was observed. A reference interval of 14-28 mg/L (67-133%) was established.

Delayed-type hypersensitivity (DTH) to 2-phenyl-4-ethoxymethylene-5-oxazolone (oxazolone) was found to be under multigenic control in inbred, H-2 congenic and intra-H-2 recombinant strains of mice. A high response was associated with haplotypes H-2d,a,k and low response with haplotype H-2b. DTH to oxazolone was high or intermediate in different F1 hybrids of high and low responder mice. In F2 and backcross generations a higher response was associated with the "dd", than with "bb" phenotype, while intermediate response was found in the heterozygote "db" mice. A study of H-2 recombinant strains suggests that a gene controlling the DTH response maps in the I-B subregion of the H-2 complex. The response was significantly modified by gene(s) which are not linked to the H-2 complex and have not been mapped. Since congenitally athymic nude (nu/nu) mice did not respond to oxazolone, this contact sensitivity is belived to be a T cell-dependent immune response.

No abstract

No abstract