I and i antigens of human erythrocytes : their detection by means of immunofluorescence technic and their changes during ontogenesis]

I and i antigens were detected by indirect immunofluorescence on human erythrocytes. 80% of the cord blood cells were brightly fluorescent with anti-i, 15% only with anti-I. In adult blood, this ratio is reversed, 2% only of the cells being intensively labelled with anti-i. The percentages characteristic of adult blood are established within the first 8 months of life.