Human Pulmonary surfactant-associated protein A,SP-A ELISA Kit

The Human Pulmonary surfactant-associated protein A (SP-A) ELISA kit is a solid-phase immunoassay specially designed to qualitatively measure human SP-A in serum, plasma, cell culture supernates, or urine. It is based on the Sandwich-ELISA mechanism. SP-A in the sample is bound to the capture antibody immobilized on the 96-well strip plate and then sandwiched with the biotinylated SP-A antibody. After the addition of HRP-avidin and TMB substrate, the solution in the wells turns blue. The color reaction is stopped by adding the stop solution into the wells, and the color changes from blue to yellow. The color intensity is positively proportional to the SP-A bound in the initial step. The SP-A concentration can be calculated according to the standard curve. This kit is tested with high sensitivity, strong specificity, good linearity, precision less than 10%, recovery with 89%-100%, and lot-to-lot consistency. More validation information is described in the product instructions.

SP-A is a hydrophilic calcium-dependent (C-type) lectin primarily synthesized and secreted by the alveolar epithelial type II cells of the lung, as part of the pulmonary surfactant. It is involved in the maintenance of pulmonary tissue homeostasis by reducing the surface tension of fluids that coat the lung. SP-A binds different pathogens such as viruses, bacteria, fungi, and the nematode Schistosoma mansoni, via their carbohydrate recognition domains (CRDs), and act as opsonins to trigger the host’s innate immune response. In some cases, SP-A displays its own microbicidal activity by increasing the permeability of the pathogen cellular membrane. Overall, SP-A opsonized-microorganisms enhances their attachment to phagocytic cells, with subsequent pathogen clearance. Additionally, SP-A has also been demonstrated to participate in the control of pulmonary inflammation including allergy and asthma.