Perhaps you could measure the amount of mouse antibody antibody in plasma and serum by means of a direct ELISA using the serum and plasma as the samples and an anti-mouse IgG antibody conjugate for detection.

Hi Kalpana,

Maybe the lower Ab concentration was caused by protein degradation in the plasma samples because of the timing of sample collection? You can add some protease inhibitor into the samples before you disperse and storage. 

Thanks for the interesting question.

I agree with Adam for normalization. However, I am still skeptical about how reliable it is.

It is normal that you find low levels of antibody in plasma when compared to the serum. There are several reasons for the same. Most important reason is the presence of clotting factors in the plasma cause self-polymerization of thrombin and precipitation of proteins including antibodies in the plasma. This can reduce the amount of antibody detected in the plasma when compared to the serum. In the following article, the authors discuss the same, the validation of antibody concentration in plasma and serum during clinical diagnosis.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3019788/

The presence of clotting factors also influences the binding kinetics of the antibodies. And another factor is the timing. Since you mentioned that the initial samples are plasma and the latter are serum, the specific antibody concentration might go up. However, it depends on when you have challenged with an antigen. More information is needed to understand better.

I hope this information helps. Goodluck.

Hello, 

I agree with Ramachandramouli´s answer. Perhaps you may try to invert time and samples: first 3-6 weeks use serum and 7-11 plasma. Make a curve plasma vs serum antibodies and study the correlation, if you can replicate the experiment three times in three replicates of each antibody determination there might be a pattern you can deteremine when plotting a graphic Ab serum vs Ab plasma and you might find factor that relate both titers . I hope this can help you, 

I fear that there is no scientifcially valid method to normalize these data. Plasma and serum are different matrices and are of different composition.  In a graphical representation of the results, I would simply show the results as they are, including the jump and the explanation.

I suggest to do both serum and plasma tests for few samples and try the data normalization then to  to see if there is a big difference between the 2 measurements. If the difference lies within the experimental error, you can go ahead.