What is the difference between bone marrow and peripheral blood with respect to fixation and immunofluorescent staining? We have a problem with non-specific staining for a range of antibodies on bone marrow- but not on peripheral blood-derived cells.

Different fixation protocols, blocking, permeabilization, coating vs. non-coating, influence of EDTA and lymphoprep (used for ficoll seperation) were already tested.

The only explanation that we have, is that this repeating background pattern is caused by the composition of bone marrow. Can this be caused by a higher fat content in BM as compared to peripheral blood?