what is the importance of ruling out little "c" antigen?

[Malcolm Needs ☆]

I've read from somewhere that patient who develop anti-E are more likely to develop anti-c as well. So we usually type donor RBC for absence of c antigen. However my lab didn't type the patient for expression of c antigen, though. =/ Now I wonder...

Have read this right Eric? You would not test a patient who had made anti-E for the c antigen?

What about the fact that R1r (give or take) are approximately 32% of the random European population (giving the Basque region of Spain a wide berth, where rr is about 25%), and who will never make anti-c, whilst R1R1 people make up (give or take) approximately 16% of the random population.

Take my advice.

Rh type your patients!!!!!!!!!!!!!!!!!!

:eek::eek:

[eric1980]

Have read this right Eric? You would not test a patient who had made anti-E for the c antigen?

What about the fact that R1r (give or take) are approximately 32% of the random European population (giving the Basque region of Spain a wide berth, where rr is about 25%), and who will never make anti-c, whilst R1R1 people make up (give or take) approximately 16% of the random population.

Take my advice.

Rh type your patients!!!!!!!!!!!!!!!!!!

:eek::eek:

I will take your advice if I'm still working in the blood bank... I learn all I know about BB at work and, more recently, in BBT.com. So if there's anything I'm not taught, I wouldn't know or think about. =(

But more importantly, I now realise this possibility and will let my colleagues in BB know about it. Whether they will change their standard operating procedures due to this fact... I dare not bet...

I will let them know definitely.

[jcdayaz]

It is common practice to test for little c when there is an E present. If patient proves to be little c neg, then we will only transfuse with E, c negative units.

However, I will say that needs to be in your procedure manual if your supervisor wants it done.

The Rh system is so so immunogenic...often times hospitals try to avoid additional antibodies being formed against additional antigens.

[jayinsat]

It is common practice to test for little c when there is an E present. If patient proves to be little c neg, then we will only transfuse with E, c negative units.

However, I will say that needs to be in your procedure manual if your supervisor wants it done.

The Rh system is so so immunogenic...often times hospitals try to avoid additional antibodies being formed against additional antigens.

I agree with jcdayaz. Because anti-c can so often be found with anti-E and the possibility of developing anti-c if you are R1R1, it is best test for c antigen when anti-E is found and transfuse with E,c negative units if the patient is negative for both the E and c antigens. This goes both ways. If you I.D. anti-c and the patient is E antigen negative (regardless if you have available cells to rule out anti-E in the presence of anti-c), you should give E,c negative units. You DON'T want to create multiple and complex antibody situations down the line just to avoid a relatively minor expense of extra antigen typing.

That's just my 2 cents worth.

[Mabel Adams]

Ten or 15 years ago the AABB Tech Manual said that we should give c negative units to E- c- patients that have made anti-E. In later editions they have changed that to say that some believe this is indicated. My old workplace began this practice when the Tech Manual said we had to and my current workplace also does it. A few years back I spent some time evaluating the policy since it was no longer required and concluded thus: since both my workplaces are 100-150 miles from our blood supplier and we are surrounded by small hospitals that don't even have the capacity to do Ab IDs, it seemed worth the effort to test the patients for the c Ag and give them c neg units to prevent the production of anti-c or avoid restimulating a weak sensitization. This preserves the capacity of those little surrounding hospitals to save the bleeding patient using their usual O neg blood, or for us to tell them to just try xming Rh neg units and having a good chance they willl be compatible with anti-E. Once they make anti-c, anything in stock at these remote places is likely to be incompatible. If we were across town from the supplier, I don't think I would do it.

As for E neg patients that have made anti-c needing the same process in reverse, almost no unit that is c neg will be E+ so the risk really isn't there.

[Malcolm Needs ☆]

In the circumstances you describe, Mabel, I completely agree with what you are doing; it sounds eminently sensible (and could even save lives.

These circumstances should, however, never pertain in a small country like the UK.

:)

[Joanne P. Scannell]

Soooo ... you are automatically seeking out and transfusing only c-neg RBC's 'now' to anyone who is making Anti-E to avoid having to do so in the future in the event a patient actually starts making the antibody ... ... ...

think about that.

:/

[Malcolm Needs ☆]

Soooo ... you are automatically seeking out and transfusing only c-neg RBC's 'now' to anyone who is making Anti-E to avoid having to do so in the future in the event a patient actually starts making the antibody ... ... ...

think about that.

:/

I'm not sure, but I think what Mabel is saying is that, for a "cold" transfusion, when there is time to get in R1R1 blood, they would.

If, on the other hand, they expose people, almost deliberately, to c+ blood, then when they need a transfusion in hurry, they will be in trouble.

To me, that makes sense.

:confused:

Edited November 17, 2009 by Malcolm Needs

[Joanne P. Scannell]

Ok, so 'if we have the time, the staff, the resources, we'll seek out c-neg'?

Once exposed to c antigen, the game is over ... wait 3-10 days to see if the patient makes Anti-c. If not, don't worry about it anymore. If so, now you can continue to give c- negative.

Unless there is some literature out there that states the more units you give, the higher the incidence the antibody will be produced ... and how many units will that be?

Too many if, ands, and buts ...

[Malcolm Needs ☆]

Unless there is some literature out there that states the more units you give, the higher the incidence the antibody will be produced ... and how many units will that be?

Too many if, ands, and buts ...

Goodness me! This data has been out there for years and years. One only has to look at the many studies done on sickle cell and thalassaemic patients to fine copious data.

May I suggest, as a start, you read Chapter 3 (Immunology of Red Cells) in Mollison's Blood Transfusion in Clinical Medicine, 11th edition, Harvey G Klein and David J Anstee, Blackwell Publishing 2005? But there are many, many other books and papers that state that the more a patient is exposed to foreign antigens, the more likely they are to produce atypical antibodies. Certainly, this has been known about for nigh on 50 years, as Eloise R Gibblett wrote about it in 1961!

:angered::angered:

[Joanne P. Scannell]

I know and I agree ... multiply transfused people do tend to develop more than one antibody is well documented and seen day to day in Blood Banks around the world ... but for one particular antigen, and a highly immunogenic one at that ... who knows how many mls it takes to evoke an immunoresponse.

[Malcolm Needs ☆]

Well, in a way we do know this.

In Mollison's Blood Transfusion in Clinical Medicine (cited above), this time in Chapter 5, they talk about work showing how often giving D+ blood to a D- patient, just once, produces a response. They talk about 15% of the random population being "super responders" (my non-scientific phrase, not theirs!).

In one study, <50% of D- volunteers produced a serologically detectable after 6 months after injection with 0.5 to 1mL of D+ red cells. BUT, this implies that some of them did, and it implies that it was more than, say, 1%. To my mind, this also debunks the practice of looking for an antibody response for 14 days, and if nothing is detectable, go ahead and give more of the same.

I know that the D antigen is easily the most immunogenic of the common antigens, but K and c are not that far behind.

In Mabel's case, therefore, where her blood supplier is miles from her hospitals, it would be best to regard all of her patients as potential "super responders", particularly as there is no way of telling in which category her patients will fall, prior to transfusion.

:confused:

[BSIPHERD]

There is plenty of published information available (and I'm not going to cite it) to indicate that giving c negative blood to CCDee patients who have developed Anti-E is a good idea and improves patient safety. I don't think it's just a matter of preventing the development of Anti-c. We see, not infrequently, that when patients develop new antibodies, particularly Anti-K or additional Rh antibodies, that they may also develop autoantibodies. Some of these autoantibodies may not not be clinically significant but finding blood when you have to do differential adsorptions is a real pain.

So for me and mine, please always give c negative blood if we are CCDee and have developed Anti-E.

Belva

[Malcolm Needs ☆]

There is plenty of published information available (and I'm not going to cite it) to indicate that giving c negative blood to CCDee patients who have developed Anti-E is a good idea and improves patient safety. I don't think it's just a matter of preventing the development of Anti-c. We see, not infrequently, that when patients develop new antibodies, particularly Anti-K or additional Rh antibodies, that they may also develop autoantibodies. Some of these autoantibodies may not not be clinically significant but finding blood when you have to do differential adsorptions is a real pain.

So for me and mine, please always give c negative blood if we are CCDee and have developed Anti-E.

Belva

A few years back, there was an abstract/poster shown at an AABB meeting by a couple of colleagues of mine, Lee E, de Silva M. Unlike anti-c, anti-K in pregnancy is more likely to have been induced by previous transfusion; this can be prevented. Transfusion 2004; 44: 95 104A.

This argues that giving a c- lady c- blood is a waste of time, as many of them would produce anti-c because of pregnancy. This can be extrapolated to the fact that it is a waste of time giving anyone who is c-, c- blood.

I TOTALLY DISAGREE WITH THIS!!!!!!!!!! See my attachment in the second post in this thread as to why.

I TOTALLY AGREE WITH YOU BELVA!

:D:D:D:D