Definition of rhesus factor in English:

rhesus factor

Line breaks: rhe¦sus fac¦tor
Pronunciation: /ˈriːsəsfaktə(r)


[in singular]
  • An antigen occurring on the red blood cells of many humans (around 85 per cent) and some other primates. It is particularly important as a cause of haemolytic disease of the newborn and of incompatibility in blood transfusions.
    More example sentences
    • The discovery of the rhesus factor in human blood by American scientists also had important implications for blood grouping and, ultimately, for the development of human genetics.
    • Anti-D injections are used to counteract the rhesus factor if it proves necessary after a blood test.
    • The rhesus factor protein is the next most important one after the A and B proteins.


1940s: rhesus from rhesus monkey, in which the antigen was first observed.

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