In vitro labeling and tissue autoradiography of splenomegaly associated with portal hypertension.

Sinus hyperplasia occurring in the congestive splenomegaly associated with portal hypertension is a interesting model of steady-state hyperplasia in an adult tissue. In vitro labeling of human splenic tissue with 3H-thymidine and the demonstration of S-phase cells by autoradiography was performed to investigate the proliferative activity of sinus-lining and cordal reticular cells in congestive splenomegaly compared with that in the normal spleen. The labeling index (%) of sinus-lining cells after 2 h incubation was 0.07 +/- 0.02 in the normal spleen and 0.26 +/- 0.03 in congestive splenomegaly (t = 4.553, P less than 0.005, n = 11). This result indicated that sinus-lining cells have a long life span and that their proliferative activity is increased in congestive splenomegaly. On the other hand, the labeling of cordal reticular cells and arterial and venous endothelial cells was sparse or absent in both congestive splenomegaly controls, and these cells do not appear to be involved in sinus hyperplasia.