We have a case where a 55-year old AB neg patient, recently treated for colon cancer, has developed an anti-D. (A few T&S's ago, apparently the anti-D was coming up as a weak equivocal.)  She had previously developed an anti-C, and has received about 20 Rh negative units over the past few months.. \

 

As far as we know, she has never been given anything positive for D (Yes -- including platelets). 

 

Can anti-D be induced by something other than an exposure to the D antigen that is present on blood cells?  Even if she was exposed in the far past (say by a pregancy where the Rhogam did not work 100%), and her titer had dropped to nothing, what would make it come back up now?

 

Scott

Maybe one of the Rh-negative donors was a DEL?

Or anti-C and anti-G

The G "pseudo D" theory is interesting. Reading up on it, it appears that certain C positive, D neg red cells can appear to have a D antigen, which would induce anti-D in a D negative recipient.

I suppose this may have happened back when this particular patient was initially transfused with presumably C (and G) positive RBCs (before her screen became positive and we started using only C neg units.) And it is only now that the titer has risen high enough to identify the anti-D.

The really really weak D el seems to be a possibility also.

Additionally, this patient may have gotten IVIG treatment, possibly giving her passive anti-D.

Scott

For what it is worth, my vote is very firmly in the anti-C+G camp.

Just curious Malcolm, do you see many of these in those D neg patients who are producing anti-C?

 

Scott

Hi Scott,

 

I can't give exact figures as 1) I am not at work (and I'm not certain that we keep such figures anyway) and 2) I've just got off a 10 hour flight from Las Vegas, having had a 10 hour flight there a couple of days back, so I am more than a bit jet lagged, but, empirically, we see a surprising number.

Malcolm, if you make your jaunts to the US any shorter you'll be turning around over Nova Scotia.

Tell me about it Phil!!!!!!!!!!!!!!!