Fatty acid-binding proteins (FABPs) are a class of cytoplasmic proteins that bind long chain fatty acids. FABPs are small intracellular proteins (~13-14 kDa) with a high degree of tissue specificity. They are abundantly present in various cell types and play an important role in the intracellular utilization of fatty acids, transport and metabolism. There are at least nine distinct types of FABP, each showing a specific pattern of tissue expression. Due to its small size, FABP leaks rapidly out of ischemically damaged necrotic cells leading to a rise in serum levels. Ischemically damaged tissues are characterized histologically by absence (or low presence) of FABP facilitating recognition of such areas. Liver-type fatty acid binding protein (L-FABP, FABP1) is predominantly expressed in liver. The L-FABP protein is derived from the human FABP1 gene. L-FABP is a sensitive marker for cell damage of liver cells in vitro and in vivo. L-FABP is also a marker for rapid hepatocyte lysis in vitro (as for example in toxicology assays) and for detection of liver damage during and after transplantation. Serum/plasma and urine of healthy individuals contains approximately 12 ng/ml and 16 ng/ml L-FABP, respectively.
The human L-FABP ELISA kit is to be used for the in vitro quantitative determination of human L-FABP in serum, plasma, urine, and cell culture supernatant samples. This kit can also be used for in vitro quantitative determination of swine L-FABP in serum, plasma, urine, and cell culture supernatant samples. In order to determine the results for swine, calculated concentrations should be multiplied with 1.8.
The human L-FABP ELISA is a ready-to-use solid-phase enzyme-linked immunosorbent assay based on the sandwich principle with a working time of 3½ hours.
The efficient format of 2 plates with twelve disposable 8-well strips allows free choice of batch size for the assay.
Samples and standards are incubated in microtiter wells coated with antibodies recognizing human L-FABP.
Biotinylated tracer antibody will bind to captured human L-FABP.
Streptavidin-peroxidase conjugate will bind to the biotinylated tracer antibody.
Streptavidin-peroxidase conjugate will react with the substrate, tetramethylbenzidine (TMB).
The enzyme reaction is stopped by the addition of citric acid.
The absorbance at 450 nm is measured with a spectrophotometer. A standard curve is obtained by plotting the absorbance (linear) versus the corresponding concentrations of the human L-FABP standards (log).
The human L-FABP concentration of samples, which are run concurrently with the standards, can be determined from the standard curve.
Normal human blood samples (plasma), containing baseline levels of human L-FABP, were spiked with human L-FABP] in concentrations of 0.2 and 5 ng/ml. Samples with and without L-FABP were incubated for 1 hour at room temperature. Samples were measured using the ELISA. Values for L-FABP ranged between 86% and 102% (mean 94%).