CD27 and infection: We assayed some additional cell types which did not provide any discrimination, without presenting the results; CD34 + CD45 low hematopoietic progenitor cells, present in peripheral blood at a fraction of 0.1% of all leukocytes and reported to become dramatically increased during an infection [16]; plasmacytoid dendritic cells [13], reported to increase during viral infections and in mixed connective tissue disorders; CD27 and CD45R0 memory and effector subtypes of CD8 + T cells, reported to be affected during persistent virus infections [17].