Differential effects of a single dose of cyclophosphamide on T cell subsets of the thymus and spleen in mice: flow cytofluorometry analysis.

Abstract

Sequential changes in the distribution of lymphocyte subpopulations of the thymus and spleen in BALB/c mice (male, 8-weeks old) during 2 weeks after a single i.p, injection of cyclophosphamide (CY, 200 mg kg body weight) were studied mainly through the use of CD4, CD8 and CD3-E markers together with single-or two-color flow cytofluorometry. In the thymus on Day 2 after CY treatment, a marked decrease in the number and proportion of PNAh', CD3-and CD4+CD8+ double positive (DP) subpopulation was observed in parallel with a marked reduction in the thymus weight, cortical area and total thymocyte number. This phenomenon might be associated with the decrease in the percentage of thymocytes at the S phase of the cell cycle on Day 1 and 2 after CY treatment, owing to the depletion of the rapidly dividing cells in DP subset. There was a significant reduction in the number and proportion in CD4+ single positive(SP) subset on Day 7. The cell number of CD8+SP subset continued to decrease during Day 7 to Day 14. This contrasted with the behaviors of DP, CD4+SP and CD4-CD8-double negative (DN) subsets in which a considerable recovery was attained by Day 14. The spleen from CY-treated mice showed a marked decrease in the DN subset and surface immunoglobulin-positive cells, perhaps B lymphocytes, in both the percentage and the absolute cell number on Days 2 and 7, which paralleled the marked reduction in its weight and total cell number. The absolute cell numbers of CD4+SP and CD8+SP subsets in the spleen were also reduced on Days 2 and 7. The reduction of the CD4+SP/CD8+SP ratio was found in the thymocytes on Days 2 and 7 but not in spleen cells. Our results suggest that the principal target cell population of CY is the PNAh', CD3-and DP immature cortical thymocytes as well as splenic B cells. The sustained decrease in the number of CD8+SP thymocytes after CY treatment might be in part relevant to the potentiating effect of CY pretreatment on immune responses.

Noradrenergic responses of peripheral organs to cyclophosphamide in mice

“…This possibility is supported by a report that examined the effects of cyclophosphamide on the sympathetic nerve fibers in the spleen; Carlson and colleagues (Carlson et al, 1987) reported that cyclophosphamide increases the density of sympathetic nerve fibers around the arterioles of the spleen and, consistent with our results, that these fibers maintained organ norepinephrine levels even as the number of lymphocytes in the spleen decreased (Carlson et al, 1987;Karp and Szczytkowski, 2003). To our knowledge, the structural consequences of cyclophosphamide administration on the sympathetic nerve fibers of the thymus gland have not been directly evaluated, though cyclophosphamide appears to stimulate apoptosis in the thymus (Ishiyama et al, 1999) as well as reduce the number of PNA+/CD3-and double positive (CD4+, CD8+) thymocytes (Miyauchi et al, 1990).…”

Gene Expression Alterations in Immune System Pathways following Exposure to Immunosuppressive Chemicals

“…Antigen presentation/processing genes were induced by all four chemicals in thymus, but suppressed by DES and DEX, and unaffected by CPS and TCDD, in spleen. Consistent with published reports [12][13][14][15] of T cell toxicity by the chemicals in this study, CPS, DEX and DES, but not TCDD, altered CD3, CD4, and CD8 in thymus. Much mechanistic work has been performed to understand the immunomodulatory properties of TCDD, but the exact mechanism of TCDD-induced immunotoxicity remains controversial.…”

Kinetics of rebounding of lymphoid and myeloid cells in mouse peripheral blood, spleen and bone marrow after treatment with cyclophosphamide

“…The specific mechanisms of the beneficial effects of CTX, however, remained unclear. Moreover, these mechanisms have mostly been investigated during the lymphopenic phase, and few studies addressed the role of the cellular components that might be altered at the recovery phase (11, 13, 21, 22). In this study, we analyzed the kinetics of the alteration in different cell populations at different time points during both the cytoreductive and rebounding phases.…”