Which blood type is characterized by the absence of any Rh antigens?

The blood type characterized by the absence of any Rh antigens is Rh-null. Individuals with Rh-null blood type do not express any of the Rh antigens on the surface of their red blood cells, including the common D antigen associated with the Rh factor. This condition is extremely rare and can lead to complications in blood transfusions, as Rh-null individuals can develop antibodies against Rh antigens not present in their serum.

In contrast, the other blood types mentioned all contain Rh antigens to varying degrees. For instance, A+ and B- indicate the presence of the Rh antigen (positive and negative, respectively), while AB- signifies the presence of A and B antigens along with the absence of the Rh antigen (indicating that the person is negative for Rh). None of these blood types can be classified as Rh-null since they still have some Rh antigen presence.