Answer: An Rh+ person can receive Rh+ or Rh-. An Rh- person can only receive Rh- blood
Explanation: the Rhesus (Rh) group has three types, CDE. Of these, only the D locus is of general importance, and this is the one involved when we talk about Rh+ or Rh-. The D allele is dominant and DD or Dd are the Rh+ type, while dd is Rh-.
Rh- people have an immune response to the D and produce antibodies which causes blood clots and this can be life-threatening. Some Rh- people have anti-D antibodies in their blood, but the level is too low to affect Rh+ people transfused with Rh- blood. This is also unlikely because Rh+ is by far the more common type.
A particular problem arises when a mother is Rh- and the father Rh+ because the baby may be Rh+. If this happens the mother will produce antibodies to the foetus’s blood which will kill it if they cross the placenta. This is avoided by giving the mother Rh immunoglobulin injections during pregnancy which switch off anti-D antibody production.
It is rare for the C and E loci to cause a significant immune response.