High Frequency Antigens

[AB123]

We receive a lot of antibody screens that tend to be positive in all screening cells, both with or without enzyme reactivity.

 

In such cases what are the most likely culprits? 

 

Edited January 13, 2021 by srichar3
unfinished

[David Saikin]

cold agglutinins (you did say "a lot of antibody screens tend to be positive in all screening cells." 

 

[Malcolm Needs ★]

It is probable that most are auto-antibodies, as David suggests, but it could also be things like antibodies within either the Chido/Rodgers, or the Knops Blood Group Systems (if the auto is negative).

[AB123]

We run auto control with all our panels and in these cases they are negative, were a women's speciality hospital in the middle east. I'm literally getting 3 or 4 of these a week and we have no reference service so mostly they are going unidentified. I'm trying to develop our identification protocols and source additional reagents to help ID these cases but struggling to find HFA negative cells out here. 

Just to add in most cases these are pregnant women. 

[jayinsat]

What methodology are you using? Are you using tube reactions, Gel technology, or solid phase?

If tube, what enhancement medium: PEG, LISS, Albumin?

My vote is for an auto antibody, either cold or warm. I would doubt that these are antibodies against high frequency antigens showing up in the proportions you describe.

[AB123]

Column agglutination with glass beads instead of Gel from Ortho. 

39 minutes ago, jayinsat said:

What methodology are you using? Are you using tube reactions, Gel technology, or solid phase?

If tube, what enhancement medium: PEG, LISS, Albumin?

My vote is for an auto antibody, either cold or warm. I would doubt that these are antibodies against high frequency antigens showing up in the proportions you describe.

 

[Malcolm Needs ★]

1 hour ago, srichar3 said:

I'm trying to develop our identification protocols and source additional reagents to help ID these cases but struggling to find HFA negative cells out here. 

Short of getting HFA negative cells, you may be able to get recombinant blood group proteins, such as CR1 (possibly from the International Blood Group Reference Laboratory in the UK, or from Professor Axel Seltsam's company, which, I believe, is called imusyn GmbH & Co. KG.

[AB123]

I'm looking into sourcing these from a company in Germany called inno-train who provide molecular blood typing products also, I believe from the name in the IFU's provided these are the same (imusyn GmbH & Co. KG.) that you mention above.

My next question was going to be if anyone has any feedback on these techniques? 

imusyn rBGA Kits_v19_EN_RUO.pdf

Edited January 13, 2021 by srichar3

[AB123]

27 minutes ago, Malcolm Needs said:

 you may be able to get recombinant blood group proteins, 

And also my reason for asking which antigens are most likely, so I know which ones to try first rather than ordering them all. 

[Malcolm Needs ★]

25 minutes ago, srichar3 said:

And also my reason for asking which antigens are most likely, so I know which ones to try first rather than ordering them all. 

Well, this is why I suggested the CR1 rBGP, as this will inhibit the antibodies directed against antigens within the Knops Blood Group System and, my other suggestion was the Chido/Rodgers Blood Group System; just as examples.

I notice that you said that most of these patients are pregnant.  Please do not, under any circumstances, think along the lines of HLA antibodies (I am certain that you wouldn't), as these would not appear as antibodies to high prevalence antigens.  As I say, I'm sure you wouldn't, but others might.

[galvania]

Three to four a week out of how many tests?

Where are you getting your cells from?  Is the reaction strength the same with all cells?

Are you working manually or with an automat?

Have you noticed a correlation with these patients' ABO groups?

Also do you have any lookback as to whether the babies of these women were jaundiced or anaemic post delivery?  Or were they OK?

[Malcolm Needs ★]

When I got to bed last night, I suddenly realised that I may have missed out a fairly obvious cause, as I had not taken into account the fact that the patients were all pregnant.

I just wonder if these patients have all made anti-Lea and anti-Leb, as it is not unusual for the Lewis antigens to "disappear" in pregnancy, and quite often they transiently make Lewis antibodies.  If none of the cells you are using are themselves Le(a-b-), then this antibody mixture (actually, it isn't a mixture, but anti-Lea+b) can look like an antibody directed against a high prevalence antigen.

If you cannot obtain sufficient Le(a-b-) red cells to test this theory (and it is only a theory), you could try to inhibit the antibody with saliva from an Le(a-b+) individual (but don't forget to control this by diluting another aliquot of the plasma with saline).

The attached may be of interest/use.

The Lewis Blood Group System and Secretor Status.docx