Table 2─27. Phenotypes and frequencies in the MN system.
e. Enzyme treatment of red blood cells denatures M, N, S antigens but not s and
U14 (see Table 2-28).
f. Human anti-M and anti-N antibodies are occasionally encountered. They are
usually naturally occurring IgM agglutinins, rarely reacting above room temperature.
The reactions of some anti-M are enhanced by lowering the pH of the serum. Rabbit
anti-M and anti-N reagents, often available commercially, detect similar, but probably
not identical, antigens to those detected by human antiserums. Lectin reagents may
detect yet other determinants, particularly the anti-N made from Vicia graminea seeds
that appear to detect a product that occurs before N in the antigen production pathway.
In spite of this, human, rabbit, or lectin reagents are useful in typing human red blood
Table 2─28. Serologic behavior of MNSs system antibodies.