I'm trying to do immunofluorescence on paraffin sections and I'm working
with an antibody made in mouse (6F11 anti ER mouse IgG1 (ER= estrogen
receptor)) that I have  been using on mouse tissue. My secondary is a
rabbit anti- IgG1 of mouse coupled with FITC. I have a lot of background
both from autofluorescence and non  specific staining but mainly with
nonspecific staining (the autofluorescence is not as strong as the non
specific staining). Our positive control (uterus) is treated together
with the mammary gland and sectionned in  the same block and is totally
find (the staining in the nucleus is nice and strong). But the mammary
gland has a very strong extracellular staining and almost no staining in
the nucleus. I have  tried a number of changes from the original
protocol and nothing seem to work: Antigen retrieval, Histoclear, MOM
kit but I still have a high staining in the extracellular matrix. I
really appreciate any information you can share. Thank you. Ouahiba
(postdoc at LBNL, California).