Question: Can we get absolute abundance of TCR using TCR-Seq?
gravatar for CY
10 months ago by
United States
CY420 wrote:

I have a project in which I want to compare the absolute abundance of TCR across patients.

I have no problem deriving relative abundance of each TCR using TCR-Seq. How about absulote abundance?

With DNA barcode, we can calculate the amount of original fragment before PCR. Beside, I can use the same initial blood volumn. However, how can we control the initial DNA input during Library prep (Appearently, we can't use the same amount of DNA input to start because that would be pointless). Is there anyway we can do this without adding spike-in?

tcr-seq • 319 views
ADD COMMENTlink modified 8 months ago by Biostar ♦♦ 20 • written 10 months ago by CY420

Just out of curiosity: why would it be important to know the absolute abundance? And isn't relative abundance already a touchy topic due to the tiny sampling that we typically do out of the huge universe of possible clonotypes within a person's blood?

ADD REPLYlink written 8 months ago by Friederike5.2k

I gave it another thought and I got a bit confused. The relative abundance of TCR is relative to what? We can't compare the its relative abundance across patients because we got different initial DNA amount across patients, right?

The point is that we are comparing TCR status across patients (undergoing immunotherapy) and aiming to decide the group of patients whose immune systems are boosted in terms of T-cell quantity. Here we think the quantity of TCR is as much important as the diversity of TCR.

ADD REPLYlink written 8 months ago by CY420

well, hopefully the clonotype that's recognizing the tumor should be boosted within a patient, i.e. it's relative abundance compared to the other clonotypes within the sample from the same patient

ADD REPLYlink written 8 months ago by Friederike5.2k

You are right. We can compare abundance of between clonotypes within an individual. I guess it is not making much sense comparing the total TCR abundance or abundance of specific clonotype between patients (even though in theory we can do it by exacting the same amount of blood and using UMI to keep original amount of DNA fragments)

ADD REPLYlink written 8 months ago by CY420

Yeah, but it's not really a meaningful measure.

ADD REPLYlink written 8 months ago by Friederike5.2k
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