Chapter 10: Glomerular stuff
Nomenclature of the Kidney dz:
“-itis” = type III HPY – therefore it’s an immunologic dz (glomerulonephritis)
Example: Lipoid nephrosis – does that have type III? No
Example: Focal segmental glomerular sclerosis? No
Example: Diabetic glomerulosclerosis? No.
Example: IgA glomerulonephritis, diffuse membranous glomerulonephritis? Yes
When we say ‘diffuse’, this means that EVERY glomerulus has something wrong with it on renal
bx. What is ‘focal’? not all glomeruli involved.
What if dz is focal and dz in the glomerulus is focal? Have a problem – this is called Focal
What does proliferative mean? Have lots of them. So, you have many nuclei. If all the glomeruli
have a lot of nuclei, this is diffuse proliferative glomerulonephritis
If you just see thick membranes, its membranous glomerulonephritis
If you see both increased cell and thickened membrane? Membranoproliferative
The order is: blood, endothelial cells of the capillaries, underneath there is a BM, and then the
visceral epithelial cells (looks like feet = podocytes; which have spaces in between them called
slit pores) that line the bowman’s capsule. Who makes/synthesizes the GBM? Visceral
epithelial cells (podocytes). What keeps Albumin out of the urine normally? Strong negative
charge of the BM. Who is responsible for strong “-“of the BM? A GAG called heparan sulfate,
which has a strong neg charge. If we immunologically damage the visceral epithelial cell, what
do we automatically also damage? The BM, which means you’re gonna spill a lot of protein in
the urine, which means you potentially can have nephrotic syndrome if you spill >3.5 grams in
Test on Renal Bx
Stains – routine H & E hemotoxylin stains, silver stains. Immunofluorescent stain – pattern can
be linear or granular (aka lumpy bumpy), which are the only 2 patterns. These patterns are
immune complexes or patterns/Ab’s that they are detecting. Take bx, and have Ab’s with a
fluorescent tag on them. Ie want to see IgA in the glomerulus and have anti IgA Ab’s with a
fluorescent tag – if there are any, it will attach to it and make a fluorescent tag. There are also
tags for IgG, C3, fibrinogen – so can get an idea of what’s in the glomerulus and an idea of what
pattern it is in (ie linear vs. lumpy bumpy granular pattern). It doesn’t tell us where these things
are, it just tells us that they are there. What tells us where immune deposits and immune
complexes are located are EM. So, we do stains, fluorescence, and EM. How can we tell that the
podocytes are fused? Can only tell by EM b/c its so small.
Difference between Ab recognition vs. immune complexes
Detect with Ab which have 2 Ag recognition sites on the Ab. Goodpasture syndrome is an IgG anti
BM Ab’s. So, they get in the blood they get into the glomerular capillary and are directed against
the BM. Wherever there was a spot on the BM you will see an IgG Ab. There wouldn’t be one spot on the BM without IgG. So, what if we do a fluorescent tag for IgG overlying the glomerulus – what
would you see? Would see outlines of all the BM’s of the entire glomerulus. It is linear.
MCC linear pattern on immunufluorescence = Goodpastures.
Immune complexes – Ag with Ab attached and is circulating in the bloodstream, hence Ag-Ab
complex – ie lupus = immune complex dz: Ag = DNA, Ab = anti-DNA – they attach to e/o