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Monoclonal Control


Eagle Eye
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  • 3 years later...

I have more questions on this topic.

1). Is the monoclonal control only required for AB pos cord but not for full blood grouping test (including forward and reverse grouping)?

2). Is the monoclonal control required for weak D test? For what I understand, the monoclonal control is mainly used to detect spontaneous agglutination that could cause mistyping. If your RhD typing at immediate-spin is negative (or even there is negative reaction with ant-A and/or anti-B reagent), does that prove there is no spontaneous agglutination? If yes, what's the purpose of using monoclonal control in the weak D test?

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It is used to provide a negative control for the forward grouping, but is therefore only needed for AB pos patients. It is usually/often easier to require the control every time so it is not forgotten when the occasional AB pos does occur.

The control's use in weak D testing is useful when the patient has a positive DAT.

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On 8/5/2021 at 3:32 AM, Ensis01 said:

It is used to provide a negative control for the forward grouping, but is therefore only needed for AB pos patients. It is usually/often easier to require the control every time so it is not forgotten when the occasional AB pos does occur.

The control's use in weak D testing is useful when the patient has a positive DAT.

Thank you Ensis01 for your response.

We do not do weak D testing if the patient has a positive DAT. We only do weak D testing on the cord blood samples when possible. However, I would like to know how you would interpret the weak D testing when the patient has a positive DAT. Based on the inserts of the RhD typing reagents we used, there are the following statements.

"An Indirect Antiglobulin Test result with cells that demonstrate a positive Direct Antiglobulin Test cannot be reliably interpreted with respect to weak D."

"A positive Indirect Antiglobulin Test for weak D must be validated by a macroscopically negative direct antiglobulin test or a negative indirect antiglobulin test using an appropriate control."

Red blood cells coated with alloantibodies or autoantibodies of the same or similar specificity as the reagent (i.e., cells that are DAT positive) may give weak reactions. This is due to decreased availability of antigen sites because of antigen blocking or steric hindrance. In extreme cases, false-negative results may occur.

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32 minutes ago, Clarest said:

Thank you Ensis01 for your response.

We do not do weak D testing if the patient has a positive DAT. We only do weak D testing on the cord blood samples when possible. However, I would like to know how you would interpret the weak D testing when the patient has a positive DAT. Based on the inserts of the RhD typing reagents we used, there are the following statements.

"An Indirect Antiglobulin Test result with cells that demonstrate a positive Direct Antiglobulin Test cannot be reliably interpreted with respect to weak D."

"A positive Indirect Antiglobulin Test for weak D must be validated by a macroscopically negative direct antiglobulin test or a negative indirect antiglobulin test using an appropriate control."

Red blood cells coated with alloantibodies or autoantibodies of the same or similar specificity as the reagent (i.e., cells that are DAT positive) may give weak reactions. This is due to decreased availability of antigen sites because of antigen blocking or steric hindrance. In extreme cases, false-negative results may occur.

If the DAT is positive I would not do weak D testing unless I could obtain a negative DAT. The primary methods I have used to do this are: EGA and CPD. I have however used 56’C heat elation for cord and neonate samples with some success, it is however time consuming. 

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