The rat SP-D ELISA Kit is used to quantitatively measure SP-D concentrations in rat serum, plasma, or tissue homogenates. It performs well in important characteristics, including sensitivity, specificity, precision, recovery, linearity, and lot-to-lot consistency. This assay is based on the sandwich ELISA mechanism and enzyme-substrate chromogenic reaction. The solution color develops proportionally to the amount of SP-D in the sample. And the intensity of the color can be measured at 450 nm via a microplate reader.
SP-D, encoded by the gene SFTPD, is a multimeric collectin that is primarily expressed in the lung and is involved in the modulation of pulmonary surfactants, maintenance of lipid homeostasis in the lung, and promotion of innate immunity to protect the lungs from microbial and chemical insults. SP-D mainly functions to aggregate and enhance phagocytosis of dying host cells and microbes such as bacteria, viruses, fungi, and helminthic parasites thus aiding their neutralization and clearance. Levels of SP-D are related to proinflammatory immune responses, mainly when alveolar macrophages interact with the trimeric form through their CD91 receptor, activating the p38 MAPK signaling pathway to elicit Th1 responses. SP-D production is affected by various lung diseases, and SP-D is regarded as a biomarker of lung inflammation.