Malcom Needs, thank you very much! Give yourself more credit, it did appear to me that often the antigens and antibodies are not explained (expressed) properly in writing and this made it even more confusing! It is a lot to take in, but since I was already researching it makes it easier for me to understand your reply, and yes, I believe I do. I needed someone that knows about the subject to assist by addressing my specific questions, and you have. I really appreciate your help, and I will watch the lecture in the next few days and let you know how that goes. Best wishes! Kea