rravkin@aol.com

Terry, In practice I have taken units down on post-op patients who showed no signs of active bleeding and did not have orders to transfused, according to the patient's RN, and who had a negative antibody screen. I practiced this upon need and without a formal writen policy. I think that it is just good practice and good product management.

I have used selected cells of the Ficin Treated cell panel to rule out anti C and E, for which I initially used the neat panel in the presence of Anti-D.

Lab217, In speculation of the practice you present I think that the rational for it may be to conservatively assure that the donor unit is compatible in light of the potential immune compromise demonstrated in the backtype whereby a potental weakened allo antibody may not be detected through the antibody screen; the logic of which comes from the idea that if your ABO antibodies are attenuated in any way then any of the other allo antibodies would follow suite; and a weakened allo atibody although not detected through your reagent screening cells may be otherwise detected through the extended crossmatch with your donor cells which are not prepared and preserved as your reagent screening cells are; and not to mention also that the difference in cell surface antigen distribution is almost definitively different between the screening and donor cells which may also have an effect on reactivity. In short, I think that this practice is basically a highly conservative effort to assure a compatible crossmatch in light of the implications of a weakened backtype. I have to say that I have never worked anywhere that engaged this practice but I think that we can at least speculate why. I hope this helps a little.

Brenda, Amen again as the patient history is very important. However, you mention phenotyping in the presence of a known or suspected Warm Auto; I would think that unless the Warm Auto was first adsorbed the results of the phenotyping would be questionable, especially the negative reaction, given the fact that this immuneglobulin would have a great potential to coat the red cells and potentially interfere with the phenotype reactions.

lord_shadi, Does the Gel system used have an Rh control component? When you repeated the reverse type did you utilize the same Gel system, or an alternative testing system, or both? And lastly, can you give the specifics of the A and B cell preparations used? Thank you in advance for any reply.

Malcolm, Is this because the immune globulin here is predominently IgM class?

Hey Liz, I think that this is a problem for Malcolm, but as he would say, "I'll give it a go." So I will assume that you have confirmed a Warm Auto present in your specimen that you hold in your hand. Once the Warm Auto is adsorbed from the plasma content of your specimen you are left with Warm Auto Antibody Free Plasma. Now you can perform your usual antibody screening technique and if you get an inconclusive result do to week reactivity then there are several ways to enhance that reactivity, one of which can include the use of PeG. The same holds true for performing the DAT on the rbc portion of your now Warm Auto adsorbed specimen. Some other reaction enhancement techniques involve the use of Albumin or LISS with increased incubation time at 37C. The Elu would be used if your DAT is still positive and you can enhance reactivity with your eluate and screening cells using PeG as well as any other suitable enhancement techniques. I hope this helps a little. ):

We perform the eluate under circumstances given; however we specifically run the eluate with screening cells first and if positive proceed to panel. I'm not sure if others do the same but this sequence will save some time and reagents.

Chris, Not withstanding the potential antigen expression differences of your reagent cells, do you have a transfusion history for this patient for the past three months and did you perform an auto control and/or a DAT?

Malcolm, How do pre-mature (Primies?) infants fit into the information you provide? If they are a part of the population that you speak of here, how do they effect the curve? As I have had some freinds who were premature at birth they seem to have a more hyperactive immune system.

Chris, What was the reaction strength of Cell II? Do you use Diamed column technology for your screen testing?

Brenda, Just one question; the pooling of like products (Platelets an Cryo) would not alter too much, but here they are speaking of combining unlike products, and for the most part, from too different donors. Is your informative post a case of comparing apples to oranges? Could there not conceivably be some extent or level of alteration to a final whole blood product comprised of packed rbc's from one donor and plasma from a different donor? My biggest concern would be lysing or crenation of red cells.

EMB4879, Is the 1% to 2% wastage strickly Packed Cells?

Mohammad, I have worked at two different blood banks that had Irradiators for use. These blood bank's monitored for irradiation exposure two different ways using the same device, an irradiation detection pin or patch. One blood bank simply kept one of these pins inside the Irradiation Room and checked for changes to the pin at a regular time interval (I don't remember what that interval was) with periodic replacement. The other blood bank had staff issued pins which were monitored and replaced, again, with regular time intervals. I don't know if you were looking for this type of information in your thread but I hope it helps just the same.

Anna, Thank you again for your insight but I am also concerned with potential steric hinderence caused by adsorbed plasma proteins other then IgG; most notably Wartins's Jelly when performing a DAT on Cord blood, that may result in a false negative reaction. I appreciate any further insight.

Anna, Thank you once again for your time and explanation, and I if understand you correctly the rbc's are not washed when using the gel card with automation and/or manual practice. But I have to ask how a false negative DAT would be caught in the first place? It seems that in practice once the DAT is interpreted as negative no further work-up is performed on that specimen. Then if the DAT is actually positive, a certain amount of in-vivo hemolysis would occur and the patient's physician would note a decrease in hgb and perhaps order another DAT to be performed using the same methods. And it may not be caught again or if the DAT does come up positive we would certainly interpret that as a potentially delayed reaction and still not be compelled to revisit the initial specimen and perform the DAT using a different method. I would further say that the use of rbc sediment is routine but does not garantee, without washing, that they are free of bound proteins despite the separation from the plasma and the lesser percentage of plasma present in the aliquote used. Once again I look forward to your insight and thank you for your posts and your time.

Anna, Thank you for your post it does help. However, I thought that washing the rbc's also caused losely bound proteins to be removed from the surface of the rbc's and I wonder if that is possible here in Gel. Additionally, when performing a DAT using the Gel colomn card we only add 50ml of the 0.8% rbc solution to the column. There is no top layer of further reaction volume solution. So if the cells are not washed and the 0.8% rbc solution is added then any bound or unbound proteins would remain homogenious in this reaction volume causing the potential for a false negative result despite the seperation of rbc's from the reaction volume via centrugation. I have been thinking that when the DAT is run using the Gel card and automation that a washing-like effect may occur when the 0.8% rbc solution is made. I appreciate in advance any further insight.

John, If I am understanding your explaination correctly you are saying that the low concentration of rbc's and the migration of the rbc's through the gel column itself act to effect the rbc's in the same way that washing would. The only problem is that with a 4+ reaction the rbc's do not migrate through the gel colomn at all. I have used the gel cards manully for DAT testing and have washed the rbc's prior to making the 0.8% rbc solution. In an automated testing system I think that the making of the 0.8% rbc solution may have the same effect as manual washing but I am not sure. Can you please explain further and thank you in advance.

It may be worth initiating a policy, if you have not done so already, to save and properly lable all positive Gel Cards for later review; if you use the Gel Card system.

Smudge cells can also be seen in cases of viral infestation of the periferal lymphocytes, for example Mononucleosis.

Mohammad, What is the exact CAP requirement that you ask about?; and I would think that it would be a better practice to issue ABO/Rh type specific platelet and granulocyte products that have visual signs of rbc's present to reciepients that are antibody screen negative. If the recipient is sensitized then issue type specific or compatible products that have no visible sign of rbc's.

How are you measuring the concentration of rbc's in the random and single donor platelet products?

Majolica, If I could elaborate on the importance of supplying as much history as you are aware of; with respect to your Anti-Fya, in the event that over time this antibody falls to a concentration below what is detectable and no history is known then your blood bank will result the antibody screen as negative and you may recieve packed red cells that are positive for the Fya antigen, which will cause a potential reaction. This reaction will come about because when the immune system recognizes a antigen upon which it was previously sensitized it retains memory and proceeds to produce IgG class antibodies immediately and this is why antibody history is so important. Additionally, I have seen cases where antibodies were generated as a result of IVIG sesitization directed against a component of the IgG of the IVIG; in other words your immune system can develope antibodies against foreign antibodies. An example of this is the development of Anti-IgA derected against the antibody, IgA. I hope this helps a little and does not add more confusion.:)

Msdesoki, If you perform your antibody screening with tube method using LISS then take readings at all phases of testing you may be able to confirm Anti-M especially when your Gel card screening is negative.

Joan, You bring up a good piont here however, what you are actually saying is that your antibody detection method is not subject to error and so if no maternal antibodies are detected then "you do not have to give antigen negative blood." You should remember that the total volume of the neonate circulation is vastly lower then that of an adult and therefore any sensitization and/or reaction can have very serious consiquences, before/during/or after, the start of the neonates own immune system, approximately 120 days after birth; curiously the same time frame for circulating life of the very donated red cells. This is why I would think that it is better to error on the side of caution and issue maternal antigen compatible RBC's.