Hi all, I am a little bit confused about the concept behind Human Leukocyte Antigen (HLA). Part of my project right now requires me to do HLA typing from the blood samples with flow cytometry. Here are my questions. 1. The difference between between HLA class I & II compare to MHC Class I & II. From wiki, HLA genes are part of MHC genes on the same chromosome? I think I am confused about the word "antigen" in HLA. 2. The types of HLA a person can have. In each HLA I or II class, there are many subtypes, like in class I, there is HLA-A1, A2, A3...etc or B7, B8, B13.....etc or Cs...etc. My questions is that in a person, do we have one group of each in subclass (A,B,C)? For example, one would have HLA-A2, B7 and Cw01, and also one of each different group in Class II as well? 3. Heterozygous. Can one person be a heterozygote having like HLA-A2/HLA-A1? How would this affect their immunity? Will they recognize MORE antigens with WEAKER response being heterozygous? 4. Suggestions? Currently I am using flow cytometry to screen for HLA-A2 (single color), I can identify people positive or negative for A2, but what would an heterozygote look like if the above is true? Would it look like 2 peaks overlapping each other by half? What would be an cost-effective alternative method for HLA typing? Thanks a lot, I hope I am clear.