I know the blood type diet has been debunked by a lot of knowledgeable people, but personally a lot of the foods they say to avoid for my blood type give me noticeable reactions so I was thinking it has to have some merit.
I think this is a really interesting question.
In the book Genome, Matt Ridley writes about how blood types seem to affect susceptibility to different pathogens. He claims that type O people are more susceptible to cholera and less susceptible to malaria, while those with AB are less susceptible to cholera. In fact, the variability in response to a number of bacteria and viruses may be be affected by blood type. See this study for more on that.
If blood type actually affects our response to bacteria, why couldn't it have at least a small effect on our responses to potential food antigens (e.g. specific lectins and proteins)? I'm open to the possibility that the risk of specific food intolerances might be affected by blood type.
In 1945 William Boyd apparently found that lima beans contained lectins that were blood type A specific hamagglutinins. I found this study that confirmed this finding. So far, this is the only common food I've found with potential blood type specific lectin activity. There just doesn't seem to be much research on this subject.
Peanut Agglutinin Lectin loves to bind to galactose. It's a positive control you often see in in vitro studies dealing with carbohydrate/protein interactions. It binds terminal galactose residues, which blood types B and AB have. Whether than means anything is another question. I'm not going to google that for you.
For what it's worth, it also binds lactose.