70 year old, African American female, never transfused, 2 live children, no major surgeries.

O Positive, R2R2 K-, Fy(a-b-), Jk(a+b+), M+N-S-s+ phenotype per BioArray but genotypically Fy(a-b+) with GATA BB, so Fyb is silenced. DAT poly: 3+; IgG 3+; C3b3d: Weak; Saline: Neg

PEG 4+ all cells tested. 22% albumin 2+ all cells tested. Acid eluate reacts with all cells tested. Papain treated cells and 0.2M DTT treated cells react 3+; no difference.

Adsorbed X 5 with PEG R1R1, R2R2 and rr cells: 1+ to 2+

Adsorbed x 5 wih Papain treated R1R1 etc: 3+; autoadsorbed, heat eluted, papain treated cells x 3: 3+

Titer to 2048 with prozone effect between 1:8 (3+), 1:16 to 1:64 (4+), 1:128 back to 3+

Patient phenotypes: H+, P+, At(a+), Cr(a+), Vel+, Tc(a+), Lan+

Patient serum reacts with: cord cells, JMH-, Yk(a-), McC(a-), Kn(a-), Sl(a-), Wr(a-), Jr(a-), N-U-, Lu(a-b-)

Genotype shows all "Normal" high incidence antigens present

This certainly sounds most consistent with an autoantibody. Here's a few questions first:

1) Were you able to obtain DAT negative autologous cells (by EDTA-Glycine Acid or Chloroquine diphosphate treatment), and if so, did you test them with the patient's plasma and eluate to confirm that auto-reactivity is present?

2) Were the adsorbing cells used for the PeG adsorptions also papain-treated? It's possible that a component of the antibody(ies) that you are dealing with is enzyme-sensitive and that is why adsorption is not successful. You might want to test the adsorbed plasma with the adsorbing cells (papain-treated and untreated) to see if the adsorbed plasma continues to be reactive with those cells. If it is non-reactive with the papain-treated cells but reactive with the untreated cells, you could continue the adsorptions with untreated cells (with added caution since other specificities may be adsorbed out, depending on the phenotype of the adsorbing cells).

3) Are the cells you have tested with the adsorbed plasma phenotypically similar? You may want to try several different phen sim cells, since many of these cells also have low incidence antigens on them. Or you can also test the DAT negative autologous cells (previously mentioned) with the adsorbed plasma to see if autoantibody is still present.

Best of luck with sorting this out!

We believe that this is an autoantibody also, but the fact it won't adsorb and the its high titer are baffeling.

We ran EGA treated, DAT negative autocontrol with all panels and it reacted...indicating it's an autoantibody.

The PEG adsorbing cells were not enzyme treated and we ran three (3) phenotypically similar cells with all adsorbed sera with positive results.

Why don't you try autoabsorbing this instead of the allogeneic absorptions (never transfused/not recently pregnant)? . . . it looks like an auto to me.

Why don't you try autoabsorbing this instead of the allogeneic absorptions (never transfused/not recently pregnant)? . . . it looks like an auto to me.

We did do a 56C heat eluate of the patient's cells and then an autoadsorption x 3 with 3+ results on all cells tested including the phenotypically similar.

Were the PEG and enzyme adsorptions performed sequentially on the same sample? We've had cases that needed both to remove the autoantibody, i.e., the patient's plasma had an antibody mix that included components that did and did not react with enzyme treated cells.