what is the difference between o and o negative?
They also label them as either rhesus (Rh) positive or Rh negative to denote the presence or absence of an antigen called Rh factor. For example, a person with O+ blood does not have A or B antigens on the surface of the cells but does have Rh factor. In contrast, O- blood has no A or B antigens and no Rh factor.