IHC on cryosections - (Aug/15/2007 )

I'm having some trouble trying to do IHC on OCT-embedded cryosections from mouse kidney;
my rabbit anti-mouse MMP antibodies seem to work well, giving staining in the expected areas, but for some reason the rabbit IgG antibody negative control (same dilution as MMP antibodies) gives approx. equally strong staining within the mesangium. No staining is visible at other sites. Slides are treated with peroxidase inhibitor, and incubation without secondary antibody gives no staining. I'm using the Dako EnVision DAB+ kit for visualization. Antibodies are diluted in diluent supplied by Dako.
Any suggestions?

well, it looks secondary antibody isuue.

if I were you, I will either 1) change the block (to decrease non-specific binding of secondary, or 2) change diluent of antibody, or 3) simply dilute secondary more.

also, changing secondary antibody is option too.

I hope it work, Good luck

rnotk