Tests for Rh Isosensitization of Red Cells in the Newborn

Abstract

Coombs, Mourant and Race^1,2,3 have described an indirect method for the detection of weak and incomplete Rh agglutinins in human serum, and a direct method for the detection of in vivo isosensitization of red cells in babies with hæmolytic disease. The tests have been found to work equally well with the following rabbit antisera after absorption with A, B and O cells : (1) rabbit anti-human-pseudo-globulin; (2) rabbit anti-human-globulin; (3) rabbit anti-human-whole-serum. In the direct method the red cells of the baby are freed from serum by washing three times in a large volume of saline, a 2–5 per cent cell suspension in saline is then prepared and a drop of this suspension is mixed with a drop of the absorbed rabbit anti-human-serum. Cells which have been sensitized to the Rh factor show obvious agglutination within 5–10 minutes at room temperature.