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here is a fun case along with a question that I cannot wrap my head around it. 

Mother:

Anti-D and anti-G identified (both strongly reactive by PeG and saline-IAT), Anti-C ruled out by differential adsorption and elution with R2R2 cells and r'r cells.

All other common alloantibodies ruled out. She was not previously transfused or pregnant. 

TITER with R2R2 cells = 1024, titer with r'r cells - 128 (I know this titer is so unhelpful since expression on each of our indicator cells are different) 

Baby: (here is the fun part.. ready?) - on the birthday

D typing negative with MoAb anti-D reagent at room temperature with untreated cells, EGA treated cells, twice EGA treated cells.  DAT 4+ with untreated cells, EGA treated cells and twice EGA treated cells. 

Baby is fine (dont need transfusion, not hemolysing). Plasma and eluate reactive with D+ and C+ cells. insufficient sample to perform adsorption/Elution to differential anti-D from anti-G. 

eluate- reactive with D+ cells and C+ cells/ we assume it was anti-D and anti-G in there. 

Genotyping result. RHD*DAU0. Homozygote D deletion detected. So baby is heterogygote DAU-0 without a normal D gene. 

1 month later, baby came back hemolysing. 

DAT 4+ with untreated cells. Anti-D typing 4+ with EGA treated and untreated cells. DAT on EGA treated cells is negative. 

plasma and eluate reactive with C+ and D+ cells. all other alloabs ruled out. Not enough sample to perform adsorption/Elution

 

My question is.. 

The baby's red cells were clearly coated with anti-G and/or anti-D why did it not hemolyse at birth but 1 month after. 

I have heard of blocking mechanism serologically as in this case

 Does the heavy coating of antibodies makes Fc receptor inaccessible for macrophages for hemolysis? 

Could it be anti-G alone (not anti-D) coating on the red cells protecting the red cells from hemolysis by anti-D? 

 

Edited by dothandar
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Certainly, I think this is a case of a blocking antibody.

There is no doubt that anti-G is less clinically significant than anti-D in terms of HDFN, but it should not be ignored, as it has probably been under reported as far as HDFN is concerned.

I'm going to have to go back to my books to answer this properly (and it is a family day out tomorrow), but I will get back to you ASAP!

LOVELY CASE STUDY.

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