Anti-G????

[Bet'naSBB]

We have an Rh neg patient who has received 4 units of Rh neg RBC's and has made what looks to be a perfect anti-D.   We do not have a pre-transfusion sample - so the C typing is mixed field (in gel- not strong......more negative cells at the bottom of the column compared to positive cells at the top - like you might imagine in a patient who is C neg and received 1 unit of C pos blood......) leaving us to wonder if they're C pos or C neg.....  We typed the 4 units they received and one is C pos.  We "want" to say this is an anti-G - but, there's absolutely NO anti-C reactivity.  Not even with enzymes. DAT is negative. We've also scoured the few lit. resources we have and none of them address that an anti-G could / would do this.....  We even repeated the weak D's on the units...........all tested weak D neg.  Any insight??

Side note: We've checked about IVIG, other drugs - nothing.  They did get 2 units of A pos FP24 - but that, IMHO - shouldn't have caused any of this.

@Malcolm Needs??

[exlimey]

1 hour ago, Bet'naSBB said:

We "want" to say this is an anti-G - but, there's absolutely NO anti-C reactivity.

Reading between the lines, I believe you're saying that C+D- (r'r) panel cells are nonreactive, thereby excluding the presence of anti-C, If that's the case, and since said cells should carry the G antigen, it is very unlikely you're dealing with anti-G. Anti-LW may mimic an anti-D pattern by demonstrating reactivity only with D+ cells.

It's also very remotely possible that one of the donors carries a rare form of D-antigen that is not readily detected by typical commercial reagents. However, those are very rare and their ability to stimulate an immune response is not well understood.

[Malcolm Needs ☆]

I agree ENTIRELY with the answer given by exlimey.

Anti-G usually (not always, but usually) reacts more strongly with the C antigen than the D antigen, so that R1R1 and r'r red cells would give stronger reactions than would R2R2, whereas both anti-D and anti-LW would react more strongly with R2R2 red cells than R1R1 and r'r red cells.

I agree that one of the units could express an unusual D type (I was caught out once in a pregnancy case when the dad had the unusual D type of RHD(L214F)-CE(7)-D - which I thought was rather unfair of him!).

Have you tried rr cord bloods against the patient's plasma/serum sample?  The LW antigen is expressed much more strongly on cord red cells than adult red cells.

[Bet'naSBB]

This morning we tested with DTT treated screening cells - reactivity was still there.  If it had been an Lw - it should have been negative.....

 

[Malcolm Needs ☆]

Suggests to me that this really is an anti-D then.  I'll keep thinking (or trying to think at my age!).

[Malcolm Needs ☆]

I've been wracking my brains over this one, but I have hit a brick wall.

If it is not an anti-LW, I can see no alternative to an anti-D (possibly caused by a previous pregnancy - if the patient is female [or, these days, possibly a transexual who is now a male], or by one of the donors having a very rare RHD mutation).

Somebody will now come up with an explanation that is quite simple, and I really should have thought of immediately!!!!!!!!!!!

[RRay]

I've had this come up before with incomplete transfusion history (transfusions at another facility) and with IV drug use / sharing needles.  Occam's razor?

[exlimey]

I was also thinking of a prior sensitization. A weird, barely detectable D+ phenotype may not generate a new immune response, but may be enough to reactivate the primed lymphocytes in an individual who's anti-D has faded into non-detectability. Tiny re-exposure and wham ! Nice, strong, clear-cut anti-D, apparently out of nowhere.

[exlimey]

16 hours ago, RRay said:

I've had this come up before with incomplete transfusion history (transfusions at another facility) and with IV drug use / sharing needles.  Occam's razor?

Agreed....history is always a wildcard.

I had a case once where there a teenaged male individual had antibodies to red cells (I can't remember the specificity) with no apparent transfusion history. Later questioning revealed that the person was part of a "Blood Brothers" group who routinely and ritually exchanged blood through self-inflicted cuts. Each to their own.

[Malcolm Needs ☆]

48 minutes ago, exlimey said:

Agreed....history is always a wildcard.

I had a case once where there a teenaged male individual had antibodies to red cells (I can't remember the specificity) with no apparent transfusion history. Later questioning revealed that the person was part of a "Blood Brothers" group who routinely and ritually exchanged blood through self-inflicted cuts. Each to their own.

VERY good point.  When I was working at Westminster Hospital (many, many moons ago now), we came across a male Jehovah's Witness patient who swore blind that he had never been transfused, with one of the strongest polyclonal human-derived Fya antibodies I have ever seen.