Effect of cyclophosphamide on T-lymphocyte marker expression in T-cell areas of some lymphoid organs of the rat.

Surface markers on rat lymphocytes from thymus and T-cell areas of lymph node, spleen and Peyer's patches were examined in histological sections after one single dose of Cyclophosphamide (CY, 100 mg/kg body weight). A panel of monoclonal antibodies was used: W3/13, W3/25 and OX8 to investigate Pan T, TH and Ts/c marker expressions respectively. Ts/c marker expression showed a marked and significant reduction in both thymus and lymph node lymphocytes 3 days after CY treatment. This was followed by return to normal in the thymus and a significant rebound increase in the lymph node by day 7 after treatment. This Ts/c marker expression in both the spleen and Peyer's patches showed a significant increase on both day 3 and 7 after CY treatment. Mast cells were observed in large numbers in the thymus and lymph node but not in the spleen and Peyer's patches. TH marker expression was increased significantly in lymph nodes, spleen and Peyer's patches. No change was observed in Pan T marker expression in any of the tissues at any of the times examined.