Forgot to mention the C4d was on formalin fixed, paraffin embedded tissue with citrate buffer HIER and using Dako's Envision for detection. Paula Pierce, HTL(ASCP)HT Excalibur Pathology, Inc. 630 N. Broadway Moore, OK 73160 405-570-6679 405-759-3953 contact <@t> excaliburpathology.com