CD45.1 expression analysis in homozygous B-CD45.1 mice by flow cytometry. Spleen, blood and bone marrow were collected from wild-type C57BL/6 mice (+/+) and homozygous B-CD45.1 mice (Mut/Mut), and then analyzed by flow cytometry with anti-CD45.1 or CD45.2 antibodies. CD45.2 was detection in C57BL/6 mice. CD45.1 were only detectable in B-CD45.1 mice but not in wild-type mice.