In the first step, samples are incubated in the antibody-coated microtiter plate. During the second step, the plate is washed and incubated with the POD-labeled LN antibody. A substrate is added, and the reaction between POD and the substrate (H2O2, TMBZ) results in a color development. The amount of sample LN is determined by measuring absorbance using an EIA plate reader. Accurate LN sample concentrations can be determined by comparing their specific absorbances with the absorbance obtained for the Standard plotted on a standard curve.
Laminins are large multidomain glycoproteins of the extracellular matrix that are important for induction of cell adhesion, growth promotion, mediation of cell communication and enhancement of tumor cell metastatic phenotype. LN consists of alpha, beta and gamma polypeptide chains that are linked by disulfide bridges to form a characteristic asymmetric cross-structure observed using electron microscopy. LN binds to various components of the basal membrane and probably serves to link these components to one another. Cell surface receptors that may play a role in LN-mediated cell adhesion have been isolated from metastatic tumor cells and platelets. Furthermore, serum levels of LN fragments have been reported to be elevated in patients with hepatic fibrosis, alcoholic liver, hypertension, and several kinds of tumors.
