Hi all

We wanted to evaluate cell surface molecules in tumor samples using mass spectrometry, after the entichment of membrane proteins using a thermofisher kit called Mem-Per plus. We know that there is very high infiltration of immune cells. When we ran the samples, we did not detect CD45, CD3, CD4 and CD8 among the peptides.

Is this expected because these proteins have lower abundance compared to tubulins, actins and others? or these proteins have a unique biology that makes them hard to be detected? Any suggestions?