Histological Studies on Changes of Rabbit Pleura Induced by Immunostimulants and Anticancer Agents with Immunostimulants

Abstract

To estimate the histological changes of the pleura by sclerosing agents, such as OK-432, SPG, BCG ADR+OK-432, ADR+SPG and ADR+BCG were administered into the right pleural space of New Zealand white rabbits. The animals were sacrificed from 1 week to 3 weeks after administration and parts of visceral and parietal pleura were used for hematoxylin and eosin staining after the amount of pleural fluid were measured. Pleural effusion was not induced by OK-432, SPG and BCG. Combinations of ADR plus OK-432, ADR plus SPG and ADR plus BCG induced pleural effusion. Marked fibrin education and adhesion of the pleura were found only in the group in which OK-432 was combined. The histological changes caused by combination of ADR+OK-432, ADR+SPG, ADR+BCG were similar to those caused by ADR alone. Mesothelial cells were almost completely destroyed immediately after injection of ADR+immunostimulants, followed by gradual proliferation of fibroblasts in layers with time, which led to the thickening of pleura but accompanied marked infiltration of lymphocytes into the connective tissue layers, in ADR+OK-432 group. The combination of ADR+OK-432 is expected to have a clinically satisfactory effect from its stimulating effect on the pleura and histopathological findings.