PTPRC and myocardial infarction: Naïve T lymphocytes express the 205-220-kd form of leukocyte common antigen, CD45RA; T cells express the 180-kd form, CD45RO, after the first round of activation by specific antigens, Analysis of plaque lymphocytes by Sten Stemme et al showed that most plaque T cells are memory cells, i.e., express CD45RO.[47] The phenotypes to which the CD28 + CD45RA- CD8dim T cell belongs are all contrary to previously reported protective phenotypes, so we hypothesized that it is a risk factor for the development of MI.