Semiquantitative analysis of the effects of fixation and paraffin embedding on immunoreactivity of renal basement membranes to a monoclonal antibody against type IV collagen.

The effects of formalin fixation and paraffin embedding on the immunoreactivity of human kidney to a monoclonal anti-type IV collagen antibody (JK-199) were examined semiquantitatively by a modified enzyme-linked immunosorbent assay (ELISA). The intensity of immunoreactivity in paraffin sections of the tissue fixed overnight with 10% formalin was approximately 70% of that in frozen sections. Immunoreactivity reduced to this extent did not impair the specific staining of basement membranes. Paraffin sections of tissues fixed 2 days showed 50-60% of the reactivity in the frozen sections of the tissue fixed overnight; the basement membranes in Bowman's capsules were stained positively, but those in other sites were not. The paraffin sections of tissues fixed 7 or 14 days showed no specific immunostaining. The immunoreactivity for type IV collagen in the basement membranes was restored after treatment with pronase E. The immunoreactivity after the enzymatic treatment was about 150% of that in the frozen sections of the overnight fixed specimens.