Atrophy of the thymic cortex in mice with granulomatous schistosomiasis mansoni

Abstract

Thymic histopathology and granulomatous hypersensitivity were examined in CBA/J mice infected with varying numbers of Schistosoma mansoni worms. At the acute phase (8 weeks) of infection, the thymi of infected mice showed depletion of cortical lymphocytes that resulted in loss of distinction in the corticomedullary region. The degree of cortical depletion correlated directly with the intensity of infection, as assessed by total egg burden of the liver. Adrenalectomy of heavily infected mice 5 to 6 weeks after infection did not alter the course of cortical lymphocyte depletion. Thymus mass was diminished by as much as 80% in heavily infected mice. However, the thymi of lightly infected mice which survived 20 weeks of infection did not differ in histology or total tissue mass from age-matched uninfected controls. Adult thymectomy at 3 weeks of infection did not abrogate the spontaneous modulation (diminution) of granuloma formation in 20-week infected mice, although spleen cells from these mice failed to adoptively transfer suppression. Heavily infected mice which did not survive beyond the acute phase (8 to 9 weeks) of infection displayed a diminished granulomatous response that was partially restored by thymectomy carried out at 5 to 6 weeks of infection. Spleen cells from heavily infected mice (8 weeks) adoptively suppressed the granulomatous response in lightly infected recipients. It is concluded that histological changes observed in the thymus concurrent with egg dissemination and granulomatous hypersensitivity correlated with T cell-mediated regulatory events.

Flow microfluorometry analysis of alterations in T-lymphocyte subsets during murine listeriosis

“…Other workers have noted similar changes in thymic and splenic weights during experimental bacterial and parasitic infections and have postulated that systemic infection induces an efflux of cells from the thymus to the spleen (1,17,24). Although some aspects of the present study are support-LYT2 ive of this hypothesis, others are not.…”

Schistosomicidal Effects ofPavetta owariensisandHarrisonia abyssinicain Mice Infected withSchistosoma mansoni

“…periovular granulomatous response underwent spontaneous reduction in the murine model of schistosomiasis at the onset of the chronic stage of the infection (13). Granulomas were also found to be smalier in mice exposed to 200 S. mansoni cercariae, 8 weeks after infection, than in mice exposed to 25 cercariae (14). According to our results, the reduction of the granuloma size does not seem to be the direct consequence of differences in adult worm burden or egg load between the examined groups.…”

“…Significant differences in the reduction of egg numbers in the liver, in the number of adult worm pairs and in the reduction of spleen weight were observed between animals treated with ethanol (PR) or acetone (PRT) extracts of P. owariensis "red bark" variety ( Table 2). 5.5 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16) 4.0 (1.7-11.1) 23.3 (11.1-38.5) 55.0 (14.8-100) 367 Results are given as the median value and range (mm-max) in each group and is based on n. n = number of animals that survived until 12 weeks post-infection. n + = number of animals that died between 7 weeks (start of treatment) and 12 weeks post-infection.…”

Atrophy of skin-draining lymph nodes predisposes for impaired immune responses to secondary infection in mice with chronic intestinal nematode infection

“…The superficial LN atrophy and lymphopenia did not appear to be coupled to thymic involution observed in other infections [ 19 – 22 ], since the weight and cellularity of the thymus as well as Ki67 staining of thymocytes were not changed by chronic H . polygyrus infection ( Fig 4C–4E ).…”