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?