Disappearing A1 antigen?

[Mabel Adams]

In 1979 and 1983 my cells were tested with anti-A1 lectin and found to be weakly positive. My group A mother and 3 siblings test similarly although some tests were so weak as to make me wonder if they were truly positive.  My cells and those of my 2 brothers were tested in the 1980s by my ARC reference lab and were all determined to be A intermediates. I have a copy of their worksheet from testing me and they show my cells reacting 3+ with anti-H and +s with anti-A1.  My dad was O and my mom's dad was O so I don't think there are any other genes involved (and we 4 "kids" all look too much alike).

 

Today I shared some of my blood with an employee who is an online SBB student and our current anti-A1 lectin came up negative.  Should I just chalk this up to variation in lectin reagents?  I know that diseases can suppress A antigens but I hope I don't have any such ailments!  Is there any other explanation for this change in my typing results.  Can we alter the testing system in some way to make it more sensitive?  Test at 4 degrees or let sit for awhile at RT?  Controls worked great so I think the reagent is performing as expected.  We don't have any anti-H for her to use.  It was so sad not to be able to show her my claimed A intermediate cells.  

[Malcolm Needs ☆]

Hi Mabel,

I remember making Dolichos biflorus lectin way back in the mid 1970s at the Blood Group Reference Laboratory. It was, to say the least, bucket chemistry!

I am sure that it is done in a much more refined way these days, but, to give you some idea, this is the "recipe" from Boorman KE, Dodd BE, Lincoln PJ, Blood Group Serology, 6th edition, 1988, Churchill Livingstone.

"A 2g packet of seedsis soaked overnight in approximately 25ml of saline. The seeds are then ground, preferably in an electric grinder but a papper mill may be used. The extract is poued off, a further 25ml of saline added and the seeds reground. The process is repeated once more. The three amounts of fluid are pooled and stored at -20oC.

The ground seeds are again soaked overnight. The extraction procedure is repeated the next day until the seeds are thoroughly macerated and the volume of fluid has reached about 600ml. The process can be completed on the third day or continued over several days.

The pooled extract is filtered through several layers of gauze to remove coarse particles and frozen overnight. After thawing, it is centrifuged preferably using a high speed centrifuge, after which the supernatant is collected and frozen and thawed once more. It is examined for coarse particles which tend to come out when the extract is stored and if necessary it is refiltered and/or centrifuged to remove these. When the suspension is fine, it is standardised by testing by both tile and tube techniques at various dilutions against A1 and A2 cells.

The Dolichos extract should be used at a dilution which gives strong agglutination with A1 cells while being negative with A2.

The extract can be freeze-dried, stored and reconstituted when required. This procedure is usually unnecessary, however, as it stores very well frozen at -20oC.

It is tested with a panel of known cells of sub-groups A1 and A2 as the extract may need dilution to give clear negatives with A2 cells."

We may have come a long way from this "recipe", but my firm bet is on the reagent being the cause of your disappointment!

As a matter of interest, I have, in our walk-in fridge, a small box of Dolichos biflorus seeds that once belonged to Dr. George W Bird himself!

[Dr. Pepper]

I've always wondered how on earth people had the time and money (and slave laborer research assistants) to do this? How many other seed extracts did they have to search through before finding the dolichos, ulex, vicea etc that did something with certain red cells and not with others. And finding the best recipe for preparing it. What a colossal amount of tedious work! I have trouble just finding the second blue sock in my sock drawer. Happy Thanksgiving to all.

Phil

[mollyredone]

Phil, It's on the right side of the drawer!!

[pstruik]

... and it will always be the last one you pick ...

 

 

 

 

 

(because of the general contrariness of the universe and also that you stop looking once you've found it}

[galvania]

What do you all mean - 'I don't know how they HAD the time'!?  Go into the present tense.  Anti-A1 lectin is still being made......

[Dr. Pepper]

What do you all mean - 'I don't know how they HAD the time'!?  Go into the present tense.  Anti-A1 lectin is still being made......

Anna, I hope the technique now is a little more automated than Malcolm grinding away for hours. I was thinking more of an underpaid research assistant staring at thousands of piles of seeds on a table stretching off to infinity and wishing he'd gone into library science instead. 

 

And how did Mollyredone know that the blue socks ARE on the right????

[aafrin]

Mabel, we have found that A1 lectin works better at 4 C than at RT (25 C), so keeping the tubes in refrigerator for 15-30 minutes may be helpful. Just check.