An individual that has Rh negative can develop anti-Rh antibodies when exposed to the Rh positive antigen.Rh antibodies are not available in the blood of individuals with no previous exposure to them. Hence if this is the first time for the person to be exposed to the RhD,no immediate danger will occur.
However, after exposure to Rh antigen the person will form antibodies against it thus such a patient can experience severe transfusion reactions if future transfusion with Rh positive blood is done.