Giardia muris infection in mice with concurrent graft-versus-host reaction

The effects of concurrent graft-versus-host reaction (GvHR) on the course of Giardia infection in CBA x BALB/c F1 mice have been examined, to test the hypothesis that T-cell-mediated immunity, in the form of a local DTH reaction, alters the host-parasite relationship in favour of the host by changing the physical environment of the parasite. GvHR did not enhance immunity, indeed mice infected with Giardia at a late stage of GvHR had significantly higher faecal cyst excretion and prolongation of the plateau phase of infection, indicating a degree of immunodeficiency.     

Seminal Fluid and the Expression of MHC Class I Antigens in the Placenta of the Rat

PROBLEM : To determine whether seminal fluid influences the expression of MHC class I antigens on the surface of basal trophoblast cells in the placenta of the rat. METHODS : Transfer of DA × DA embryos into a WF (allogeneic) or DA (syngeneic) recipient made pseudopregnant by hormonal treatment followed by mating with a vasectomized male (seminal fluid) or by mechanical stimulation (no seminal fluid). Antigen expression was determined by electron microscopic immunocytochemistry using the appropriate gold-labeled monoclonal antibodies. RESULTS : Seminal fluid did not affect the expression of MHC class I antigens on the surface of the basal trophoblast in either allogeneic or syngeneic matings. CONCLUSIONS : The suppression of the expression of paternal class I antigens on the surface of the basal trophoblast cells in allogeneic pregnancies most likely occurs at the genome level shortly after fertilization.     

Murine Trophoblast Failure and Spontaneous Abortion

PROBLEM: Infection has been proposed to initiate abortion, and the role of viruses in spontaneous resorption in mice has not been tested. METHOD: The anti-viral drug ribavirin (1-β-D-ribofuranosyl-1,2,4-triazole-3-carboxamide) was fed to CBA/J and C3H/HeJ female mice beginning on the morning after mating with DBA/2J males. RESULTS: Ribavirin treatment increased the rate of abortion (resorption) on day 13.5, and this was associated with retardation of the rate of embryo development and hypoplasia of the trophoblast. There was a reduction in trophoblast-dependent decidua-associated soluble suppressor activity, but there was no maternal mononuclear cell infiltrate of the type reported in association with resorption of semiallogeneic and xenogeneic mouse embryos. This may be due to an immunosuppressive effect of ribavirin. Ribavirin was able to potently suppress proliferation of mouse trophoblast and mastocytoma cell lines in vitro. CONCLUSIONS: There are several drug-induced murine abortion models that provide useful insights into potential mechanisms underlying spontaneous pregnancy failure, but in the ribavirin model, a direct impairment of trophoblast development appears to be responsible.     

Phagolysosomal pH and Location of Particles in Alveolar Macrophages

Phagolysosomal pH and Location of Particles in Alveolar Macrophages.NYBERG, K., JOHANSSON, U., JOHANSSON, A., AND CAMNER, P. (1991).Fundam. Appl. Toxicol. 16, 393–400. Fluorescein-labeledsilica particles (FSP) were instilled into the tracheae of rabbits.Groups of four rabbits were killed after 24 hr, 1 week, 1 month,or 3 months and their lungs were lavaged. Phagolysosomal pHin the alveolar macrophages (AM) was measured using microscopefluorometry with FSP as a probe. Due to the marked decline ofthe fluorescence intensities from the FSP between 1 and 3 monthsafter instillation, it was not possible to measure pH at 3 months,but the values from 24 hr, 1 week, and 1 month were quite similar,with group means of 4.8 and 4.9, respectively. PhagolysosomalpH in AM which phagocytized the FSP in vitro showed values abouthalf a pH unit higher. AM from rabbits lavaged at 1 week hadmore lysosomes in contact with the FSP-containing phagolysosomesand a higher degree of vacuolization between the FSP and thephagolysosomal membrane than AM lavaged at 1 day. The locationof the FSP in the AM appeared to be similar in rabbits lavagedafter 1 week and 3 months. In histologic sections from the lungsthe large majority of the FSP were within cells at all timepoints.