Compensatory Changes Following Splenectomy in Bartonella Free Rats

Abstract

In rats that were carriers of Bartonella muris, certain changes were observed, following splenectomy and recovery from the anemia, in the hemocytoblastic tissue and in the reticular and endothelial elements. These changes appeared 3 to 5 months after splenectomy and were associated with immunity to further infection with Bartonella muris. The changes consisted primarily of hyperplasia of hemolymph tissue, hyperplasia of reticular and endothelial elements of lymph nodes, the formation of lymphoblastic foci periportally in the liver and peribronchially and perivascularly in the lung, regeneration of all elements of the thymus and marked hyperplasia of all elements of bone marrow (increased hematopoiesis). In view of the presence of coincident latent infection in the rat, the compensatory changes described following splenectomy in rats of Bartonella carrier stock were difficult to evaluate. What was due to the absence of the spleen and what to previous Bartonella muris anemia remained uncertain. Studies were therefore made in rats in which the exacerbations of latent infections following splenectomy could be excluded. Six Bartonella-free rats, 3 months of age, of Wistar stock, were splenectomized and killed 6 months later. Six unsplenectomized rats of the same age and stock were killed at the same time. The presence of Bartonella infection was excluded by red blood cell counts and smears of peripheral blood at frequent intervals. The anatomical changes observed were similar to those found in splenectomized Bartonella-carrier rats but less extensive. The liver showed little if any perivascular lymphocytic infiltration. The Kupffer cells were not enlarged, nor were they more prominent in phagocytic activity than in normal rats.