Column enzyme immunoassay for secretory immunoglobulin A in serum.
This enzyme immunoassay for specific measurement of secretory immunoglobulin A concentrations in human serum involves use of a small chromatographic column as a solid-phase. Serum samples are incubated for 2 h with beta-D-galactosidase-labeled antibody to secretory component, then passed through a 0.1-mL Sepharose 4B column containing antibodies to human immunoglobulin A. After the column is washed to remove the unbound label, the buffer in the column is replaced by a solution of o-nitrophenyl-beta-D-galactoside (a beta-D-galactosidase substrate) and incubated at 25 degrees C overnight. The enzyme reaction is stopped by washing the column with sodium carbonate solution, and the absorbance of the eluate is measured at 420 nm. The concentration of secretory immunoglobulin A can be determined with a minimum detectable sensitivity of 3 mg/L, without interference from free immunoglobulin A and secretory component in the same samples.
D000906:Antibodies; D002845:Chromatography; D003429:Cross Reactions; D006801:Humans; D007124:Immunoenzyme Techniques; D007070:Immunoglobulin A / Q000276:immunology / Q000302:isolation & purification*; D007128:Immunoglobulin Fragments / Q000032:analysis*; D012635:Secretory Component / Q000032:analysis* / Q000276:immunology; D001616:beta-Galactosidase
D000906:Antibodies; D007070:Immunoglobulin A; D007128:Immunoglobulin Fragments; D012635:Secretory Component; D001616:beta-Galactosidase