I will say right up front that I have no clue what is causing this and I am looking for ideas because I have stared at it for too long.

We got a male patient who had been transfused at another facility in April with multiple units, including 5 Rh positive units due to an emergency, and was transfused a couple of units again in June . The facility reports that his screen was negative in June. Now he is here for an aneurism repair. He types as O Negative, Direct Coombs 1+ with polyspecific and IgG antisera. The eluate is 1+ with all cells tested. The antibody screen and panel in solid phase is 3+ to 4+ with all cells. The antibody screen and panel by LISS show variable reactivity (4+ with D positive cells at Coombs and nearly all D+ cells react at 37C, so I'm pretty sure there is an anti-D). D negative cells range from weakly positive to 2+.

So, we cleverly perform a differential PEG adsorption to sort things out. All the D positive cells we run are positive with all three adsorbed sera w+ to 3+ (3+ with rr adsorbed sera, so that is the anti-D, the R1R1 and R2R2 adsorbed sera are w+ to 2+). All the D negative cells are negative with all three adsorbed sera.

Now, I am making the assumption that the adsorption worked, since I got negative cells. I don't know if that is a good assumption or not. So what would be left behind by all 3 sera that reacts only with D positive cells? Wouldn't anti-LW be adsorbed out by the Rh positive cells?

:confused:

Edited July 27, 201015 yr by adiescast
Forgot eluate results

Good question, and you are absolutely correct about the D+ adsorption cells taking out an anti-LW.

What I am about to suggest may be complete and utter rubbish, but I just wonder if this patient has a really, really strong alloanti-D, together with a comparatively weak non-specific auto-antibody, and the adsorptions took out the weak non-specific auto-antibody, but left some of the really, really strong alloanti-D, and that further adsorptions with the R1R1 and R2R2 cells may well take out the remaining anti-D, whilst, of course, the rr cells would not.

This is only a thought.

:confused::confused:

I was afraid you would say that. I ended up calling the anti-D and warm auto and "CRA" ("Coombs Reactive Antibody" - our short for "how would we know what it is?"). We didn't have enough adsorbing cells to repeat the adsorption to try to remove the activity. Maybe the next time the patient comes in...

Can't you use the same cells over and over again with a PeG absorption? I think you can.

i thought you had to use fresh cells in the subsequent rounds because all the available antigen became saturated during adsorption? i'm kind of queasy thinking about how many R1R1 and R2R2 cells i've been discarding after use.........i'm rr so sometimes, i've used what's on tap for these.

I will say right up front that I have no clue what is causing this and I am looking for ideas because I have stared at it for too long.

We got a male patient who had been transfused at another facility in April with multiple units, including 5 Rh positive units due to an emergency, and was transfused a couple of units again in June . The facility reports that his screen was negative in June. Now he is here for an aneurism repair. He types as O Negative, Direct Coombs 1+ with polyspecific and IgG antisera. The eluate is 1+ with all cells tested. The antibody screen and panel in solid phase is 3+ to 4+ with all cells. The antibody screen and panel by LISS show variable reactivity (4+ with D positive cells at Coombs and nearly all D+ cells react at 37C, so I'm pretty sure there is an anti-D). D negative cells range from weakly positive to 2+.

So, we cleverly perform a differential PEG adsorption to sort things out. All the D positive cells we run are positive with all three adsorbed sera w+ to 3+ (3+ with rr adsorbed sera, so that is the anti-D, the R1R1 and R2R2 adsorbed sera are w+ to 2+). All the D negative cells are negative with all three adsorbed sera.

Now, I am making the assumption that the adsorption worked, since I got negative cells. I don't know if that is a good assumption or not. So what would be left behind by all 3 sera that reacts only with D positive cells? Wouldn't anti-LW be adsorbed out by the Rh positive cells?

:confused:

Adiescast,

Is it possible that if this is a brand new antibody you are seeing a predominant IgG concentration and a lesser concentration of the IgM that would have originally been generated and may be crossreacting do to it's lesser specificity?

My first impression was what Malcolm described: A nonspecific warm autoantibody (that could be adsorbed out) and a really strong, potent alloanti-D.

Donna