antibody screening in Indian population using Caucasian cell panel?

[TimOz]

Hi Linda,

You pose a good question with a complicated anser. It really goes both ways. Asian populations living in Predominantly caucasian population will expose Caucasians to vMNS antigens if they donate blood or a male Asian fathers a child to a Caucasian BUT it is a numbers game. Roughly 5% of many Asian populations are vMNS Ag positive so 100% of caucasians can make the antibody and 95% of Asians can. The same is true of Kell but he other way. 5-8% of caucasians are Kell Ag pos but Asians almost never. In a general sense the more ethnically mixed a population is the wider the range of antibody specificities is seen but not always the antibody incidence in the population. I think this is more due to the pregnancy rate and the use of blood and blood products. The antibody incidence in most Asian populations is quite low at around 0.8% of Hospital patients.

Certainly the antibodies in Australia and the US are becomming of "wider" specificity. We see reports of vMNS becomming more common. I guess the message is use screening cell that are suitable for your population and remember that they fail. A negative antibody screen does not mean no antibodies.

[madhu]

As of now we have no definite data on the prevalence of the already 'known' or the commonly found antigens on available cell panels, in our country, leave aside the unknown or the rare ones.So what you may detect in your bloodbank has probably been 'missed' by the other blood bank where the patient received his previous transfusions.

Keeping in mind the diversity of the testing done in blood banks in India - ranging from a ABO/D group + saline cross match only at one end to the other end of those institutes performing an AHG cross match, and some doing the whole lot of ab screen and AHG cross match, it would be advisable to perform both - AB screen and the AHG cross match for patients in India.

Also bearing in mind that in India, as you have put it yourself, few people are aware of the subject of Immunohematology in details to also undersatnd its repercussions. So you actually do not know what the patient has been transfused till you receive their sample.

I work with a manufacturer of the specialised reagents and we have a small reference laboratory as part of our technical support to our customers.In so many years I have processed samples and seen antibodies- single and multiple - in so many cases which shouldn't have been there had we been practising the basics.Most common to the rare ones have been detected in the lab - including an anti-Kpb to some rare blood groups antigens too.

[madhu]

OOps...I was trying not to be obvious that i work with the vendor but I had not read all the previous posts;)...so Anna and I do belong to the same team and yes, we do process the samples received. But if I am not mistaken, the numbers in the study mentioning the missed antibodies on the panel, these were never further investigated to determine their clinical significance. Without being biased;) towards our own products, I have to repeat what I said...we need to have a really in depth study of the antigen prevalence in our country - for the commonly known antigens first and then the rare ones, simply because we not only have a huge population but a very diverse gene pool being carried forward especially with the social structure of marraiges within communities n all. Leave aside Indians being exposed to Caucasion donations, we have a major difference even in the different zones in our own country.

As noted by me during the various interactions with the users of the gel, I have noticed a very significant difference in the percentage of 'incompatible ANG cross matches' or positive ab screen in the South and North of India too.