I was informed by my senior tech that Bg antibodies react better with the older Bg positive cells. Can someone please explain the reason?

 

 

 

I hate to say this, but, as far as I am concerned, this is nonsense.  Indeed, like CR1-related antigens, the "older" the red cells, the weaker the antigens.

The easiest way of seeing whether a reaction is due to a Bg antibody is to use red cells that are Bg Negative in the first place, or,if you think the reactions are due to anti-Bg, treat the red cells with chloroquine diphosphate, which will remove Bg antigens from the red cells.

Thanks, Malcom. I thought so too.

 

Definitely nonsense.

In my experience, antibodies to Bg antigens ONLY react with the freshest of cells, and only with individuals with unusually strong expression of the antigens, e.g., Bg(a+s). Even when the odds are stacked in your favor - fresh cells from an individual with a strong expression, you're only likely to get barely macroscopic results. It can be very frustrating to chase down one of these to identify it.

We had a patient with an antibody to one of the Bg antigens.  I remember that dealing with it was not straightforward.  They are (I think) HLA antigens.  Issitt says that the antigen expression is variable even in the same donor or patient.  I didn't see anything about sample age, but I just glanced over the entry.  It is in Chapter 19 of the third edition of Applied Blood Group Serology.  Be aware that this was published in 1985, and so relies on serology alone.  

Baby Banker, you are quite correct in quoting Issitt concerning the fact that Bg antigens "come and go" in terms of expression on red cells, even from the same donor, not least because they are not intrinsic to the membrane, but are adsorbed from the plasma (a little like Lewis antigens, but not identically).  Back in the day, this used to play merry Hell with the donors we used to make up our panels in the UK.  Now we tend to use the same set of donors over and over again (with the donations aliquoted and frozen), and chosen so that their HLA types do not allow for the expression of Bg antigens.

2 hours ago, Baby Banker said:

Issitt says that the antigen expression is variable even in the same donor or patient.  I didn't see anything about sample age, but I just glanced over the entry.

I am Bg(a+) and my expression is usually quite strong; it got super strong after a bout of Infectious Mononucleosis.

I have seen my own cells react with examples of anti-Bga when the cells are fresh and then reactivity dwindle to nothing as cells from the very same collection tube age.