In 1979 and 1983 my cells were tested with anti-A1 lectin and found to be weakly positive. My group A mother and 3 siblings test similarly although some tests were so weak as to make me wonder if they were truly positive. My cells and those of my 2 brothers were tested in the 1980s by my ARC reference lab and were all determined to be A intermediates. I have a copy of their worksheet from testing me and they show my cells reacting 3+ with anti-H and +s with anti-A1. My dad was O and my mom's dad was O so I don't think there are any other genes involved (and we 4 "kids" all look too much alike). Today I shared some of my blood with an employee who is an online SBB student and our current anti-A1 lectin came up negative. Should I just chalk this up to variation in lectin reagents? I know that diseases can suppress A antigens but I hope I don't have any such ailments! Is there any other explanation for this change in my typing results. Can we alter the testing system in some way to make it more sensitive? Test at 4 degrees or let sit for awhile at RT? Controls worked great so I think the reagent is performing as expected. We don't have any anti-H for her to use. It was so sad not to be able to show her my claimed A intermediate cells.