Increased proliferative activity of the renal tubular epithelium is thought to be a prerequisite for renal
cyst formation by many investigators. However, in humans, the exact in vivo proliferation rate of epithelial cells lining these
cysts is not known. In this study, which used immunohistochemical methods with an antibody to
proliferating cell nuclear antigen (
PCNA), the proliferation index (PI) (percentage of
PCNA positive cell nuclei among epithelial cells lining the renal
cysts) was determined in 10 cases of
autosomal dominant polycystic kidney disease (
ADPKD), 8 cases of
autosomal recessive polycystic kidney disease (
ARPKD), and 8 cases of acquired
cystic kidney disease (ACKD).
Cysts with proximal and distal nephron phenotype and
cysts with markedly thickened basement membranes, as well as
cysts lined by atrophic (flattened), "regular" (cuboidal or cylindrical), and hyperplastic epithelium, were evaluated separately. The overall PI of
cyst epithelium (excluding hyperplastic
cysts) was 2.58 in
ADPKD, was 10.5 in
ARPKD, and was 3.61 in ACKD. Overall, there were only minor differences in the PI between the various types of
cysts.
Cysts with hyperplastic epithelium in ACKD (unlike in
ADPKD) showed a high PI (9.1). For comparison, the PI of two
renal cell carcinomas occurring in two ACKD cases was also determined (13.70 and 8.67%). The PI of tubular epithelium in normal kidneys was only 0.22 to 0.33%, depending on the tubule segment. In contrast, in
polycystic kidneys, those noncystic segments of the nephron from which the
cysts are thought to originate (distal nephron (specifically collecting duct)) in
ARPKD, primarily distal in
ADPKD, proximal and distal in ACKD, had PI values similar to those of the
cyst epithelium.(ABSTRACT TRUNCATED AT 400 WORDS)