Immunotropic effects of hexavalent chromium soluble compounds on the thymus and peripheral blood values in a subacute...

Intraperitoneal injections of hexavalent chromium (sodium bichromate) in the concentrations of 0.025 μg/kg (10-fold lower than MAC; group 1) and 2.5 μg/kg (10-fold higher than MAC; group 2) to rats in a subacute experiment caused dose-dependent morphological changes in the thymus: increased the counts of cells in a state of destruction, macrophages, and plasmocytes and impairs interactions between epithelial reticular cells and lymphocytes with formation of cystic cavities. Proliferation of lymphoblasts and large lymphocytes of the glandular cortical matter was detected in groups 1 and 2, of medium-sized and minor lymphocytes in group 1. Lymph node-like zones with Hassall's corpuscles, pigment foci in the cortical matter, and plasmocytes in the medulla were detected throughout the entire study in controls and in group 1 animals and on days 1 and 7 in group 2. Histiocytes, macrophages, cells in a state of destruction, and siderophages were detected in dilated lymph sinuses. Normal tissue of the gland left lobe in group 2 was completely replaced by lymph node-like zones on days 15 and 30, while the right lobe retained the structure characteristic of the gland. A dose-dependent reduction of the peripheral blood erythrocyte and platelet counts and a decrease in hemoglobin level were observed in experimental animals. On day 30 peripheral blood lympho- and leukocytosis developed at the expense of higher counts of B (CD20) and T lymphocytes (CD3) and their subpopulations - T helpers (CD4), T suppressors (CD8), and immature lymphocytes in group 1 and at the expense of higher counts of only B lymphocytes (CD20) and immature lymphocytes in group 2.