Localization of calcium-binding protein in intestinal tissue by immunofluorescence in normal, vitamin-D-deficient and uraemic subjects.

Antiserum directed against calcium-binding protein isolated from human kidneys was used for the immunofluorescent localization of calcium-binding protein in human intestine and kidney. Frozen sections of intestine obtained by biopsy from normal persons were tested by the indirect fluorescent antibody technique. Specific fluorescence indicating the presence of calciumbinding protein was observed at both the basal and apical poles of the intestinal absorptive cells while the goblet cells appeared to fluoresce non-specifically. Treatment of rachitic children with 25-hydroxycholecalciferol generally restored the pattern of fluorescence seen in intestinal tissue from normal persons. Examinations of intestinal biopsies from uraemic patients yielded variable results.