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ANORRIS

PREPARING SCREENING CELLS

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Posted (edited)

DOES ANYONE

HAVE A RECIPE FOR PREPARING 3% SCREENING CELLS?

Edited by ANORRIS
SPELL

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1 hour ago, galvania said:

You are trying to make 3% screening cells from 3% panel cells???

 

1 hour ago, galvania said:

You are trying to make 3% screening cells from 3% panel cells???

yes!!!!

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I would look for R1R1, R2R2, and rr cells.  The ones selected should allow for homozygosity of Fy, Jk, MNSs systems (not in each cell but, just like screening cells, you will want homozygous expressions in those ag systems).  Make sense?

 

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13 minutes ago, David Saikin said:

I would look for R1R1, R2R2, and rr cells.  The ones selected should allow for homozygosity of Fy, Jk, MNSs systems (not in each cell but, just like screening cells, you will want homozygous expressions in those ag systems).  Make sense?

 

Thank you!

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2 hours ago, SMILLER said:

Do you mean, like: how much packed RBCs do you add to how much saline to get a 3% suspension?  (I am determined to find the question to this answer)

Scott

I think you're joking, but just in case......

It's a simple C1 x V1 = C2 x V2 calculation. One of the few times when algebra gets applied outside of high school.

To do this accurately, you must first know the hematocrit (concentration) of your "packed cells" - this will be used as C2. For this example, let's say the hct is 75%.

C1 = desired hematocrit (concentration) - 3%; V1 = desired volume - for this example, let's say we want 100 mL of 3% cells. Using the formula and information above.... 3 x 100 = 75 x V2, which resolves to 3 x 100 ÷ 75 = 4 mL.

Ergo: 4 mL of "packed cells" in 100 ml pf PBS will yield ~3% suspension.

This process works for low cell concentrations where the added RBC volume is only a small portion of the whole (4 mL added to 100 mL). If you try to make higher concentrations, you have to take the RBC volume into consideration as part of the whole volume.☺

 

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4 minutes ago, exlimey said:

I think you're joking, but just in case......

It's a simple C1 x V1 = C2 x V2 calculation. One of the few times when algebra gets applied outside of high school.

To do this accurately, you must first know the hematocrit (concentration) of your "packed cells" - this will be used as C2. For this example, let's say the hct is 75%.

C1 = desired hematocrit (concentration) - 3%; V1 = desired volume - for this example, let's say we want 100 mL of 3% cells. Using the formula and information above.... 3 x 100 = 75 x V2, which resolves to 3 x 100 ÷ 75 = 4 mL.

Ergo: 4 mL of "packed cells" in 100 ml pf PBS will yield ~3% suspension.

This process works for low cell concentrations where the added RBC volume is only a small portion of the whole (4 mL added to 100 mL). If you try to make higher concentrations, you have to take the RBC volume into consideration as part of the whole volume.☺

 

WOW....LOL...THANKS!

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1 hour ago, exlimey said:

I think you're joking, but just in case......

It's a simple C1 x V1 = C2 x V2 calculation. One of the few times when algebra gets applied outside of high school.

To do this accurately, you must first know the hematocrit (concentration) of your "packed cells" - this will be used as C2. For this example, let's say the hct is 75%.

C1 = desired hematocrit (concentration) - 3%; V1 = desired volume - for this example, let's say we want 100 mL of 3% cells. Using the formula and information above.... 3 x 100 = 75 x V2, which resolves to 3 x 100 ÷ 75 = 4 mL.

Ergo: 4 mL of "packed cells" in 100 ml pf PBS will yield ~3% suspension.

This process works for low cell concentrations where the added RBC volume is only a small portion of the whole (4 mL added to 100 mL). If you try to make higher concentrations, you have to take the RBC volume into consideration as part of the whole volume.☺

 

Or you can just eyeball it!

Scott

 

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The Technical Manual used to have a list of antigens that must be represented in screening cells.  I haven't checked the newest edition.  I circle the required antigens at the top of a panel antigen profile, and then circle the cell number of each cell selected for the screen on the left of the profile.  Remember to take zygosity into count.  It almost always requires more than three cells.  

I usually do this when a patient has a known antibody.  I omit that specificity, and what I am left with is a screen/short panel that will only be positive if the patient has developed a new antibody.

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Can I ask why?  If you are a huge facility and are trying to save money, you would make these from whole units.  You'd have the resources to ensure they reagents are up to FDA requirements and the proper documentation was available for inspection.  If your a small facility and are trying to save money, the few pennies you might save just aren't worth the regulatory risk.

If not's not money, what might it be?

Just curious.

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21 hours ago, SMILLER said:

Or you can just eyeball it!

Scott

 

Early in my career we had a tech working in chemistry who was, shall we say, a tad bit arrogant!  I figured he had measured 5 mls while making up reagents enough times he could do it without a graduated cylinder.  He just "eyeballed" it.  It was requested he seek employment else where as one set of CAP Proficiency testing was failed miserably and his reagent prep was determined to be the cause.  :fingerscrossed:

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8 hours ago, Cliff said:

Can I ask why?  If you are a huge facility and are trying to save money, you would make these from whole units.  You'd have the resources to ensure they reagents are up to FDA requirements and the proper documentation was available for inspection.  If your a small facility and are trying to save money, the few pennies you might save just aren't worth the regulatory risk.

If it's not money, what might it be?

Just curious.

 

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