Basically, I used the same injection schedule youŒve described and it worked for CD8. But, have you checked if your mice possessed the right CD8 allele ? Monoclonal 2.43 recognizes CD8.2 (C57BL/6, BALB/c, CBA/J, B10 ...) but not CD8.1 (C3H/HeJ, DBA/2, AKR/J, ...) .... Hope this will help. Nico.