Few questions please

[bethell]

Hi all, my first post on here.

I'm no expert in blood bank issues but am very keen and would like to find some info about the following, if anyone can help I will be very gratefull. Sorry if the questions are fairly basic to some of you.

1. Cold aggs and the best way to deal with them? - Warm the sample and carry out the group and antibody screen using warmed equipment - pipette tips, cards etc. If there is no antibodies present the screen should be neg. If the screen is positive could this be due to the prescence of an antibody or the cold aggs? and how would you proceed?

Where does the keeping the patient sample at 4C for an hour come into play, if at all??

2. When identifying antibodies via a panel, why is it that the coombs panel will, most of the time, be clear cut and show easily a Kell, E, C etc but when you do an enzyme panel the panel results just dont match up to what you were expecting? Is it because the panel is also picking up non specific reactions as well as the antibody?

Hope someone can answer these questions for me, again sorry if its basic stuff!

B

[David Saikin]

Cold abs: you should use prewarmed with caution. There are some other threads that deal with PW and its pitfalls. First you have to prove that you have a cold ab. I usually run a quick screen with R1R1, R2R2, rr, auto and 2 O cord cells. I run at immed spin, and after 5 minutes at room temp and 5 minutes at 4C. Where I go with AbId after that depends on what I find (and what phase(s)). Since I use gel as my primary, it is difficult to run prewarmed (based on the spin time at RT and I don't have a "warm" area to spin in). You may do a cold autoabsorption: I put the tube in the refrig for 1 hr - hopefully will absorb all the cold ab onto the pt's red cells.

When you enzyme treat your test system you are increasing the sensitivity and, therefore, decreasing the specificity - to some extent. Enzyme pretreatment will usually enhance some clinically significant antibodies AND cold abs. It also destroys some ags so - there needs to be some logic to your use of enzymes.

[L106]

I follow David's path, but I am lazier....

To prove that the pt has a Cold AutoAb, I usually set up the 3 Antibody Screening Cells and an Auto Control (pt's plasma & his own cells), add 2 drops of pt's plasma in each tube, and incubate them in the refrigerator (5C) for 15-30 minutes. Then spin and read. If it is a Cold AutoAb causing the pt's original reactions, all 4 tubes are usually 3+ or 4+.

Donna

[BrianD]

I follow David's path, but I am lazier....

Donna

i do something similar to donna's procedure but include a well-washed O negative cord blood sample.

b.