Crohn's disease monocytes are primed for accentuated release of toxic oxygen metabolites.

BACKGROUND: Inflammatory bowel disease occurs in regions of the intestine characterized by a bowel content high in bacteria. Intestinal bacteria synthesize cell wall products such as lipopolysaccharide; when normal monocytes or macrophages come in contact with these products, they can be primed to release a number of inflammatory mediators. Mediators such as toxic oxygen metabolites released as part of the respiratory burst may contribute to inflammatory tissue damage. The aim of this study was to determine if monocytes from patients with Crohn's disease are primed by lipopolysaccharide for a greater respiratory burst. METHODS: The generation of superoxide anion was measured by superoxide dismutase inhibitable reduction of ferricytochrome c. RESULTS: Freshly isolated monocytes from active untreated Crohn's disease patients (n = 8) showed enhanced stimulated release of superoxide anion when compared with normal monocytes (n = 15; 3.80 +/- 0.12 vs. 1.02 +/- 0.06 nmol/5 min; P < 0.001). We tested the hypothesis that the monocyte priming factor in Crohn's disease serum may be lipopolysaccharide by showing that Crohn's disease serum lost its ability to prime normal monocytes after lipopolysaccharide was removed (0.25 +/- 0.25 nmol/5 min, P < 0.001). CONCLUSIONS: These studies indicate that bacterial cell wall products may be important proinflammatory molecules involved in the initiation and/or perpetuation of Crohn's disease.

[Effect of some factors on the development of exoerythrocytic stage of Plasmodium yoelii].

Using orthogonal design, the effect of environmental temperature, photoperiod, splenectomy and oestrogen levels upon the development of exoerythrocytic forms (EEF) of P. yoelii was observed. The results indicated that a significant number of viable sporozoites were cleared in the spleen, since the EEF density was much higher in the livers of splenectomized rats (1.73/mm3) than in sham-operated counterparts (0.55/mm3). The effect of high level oestrogen on EEF density was also evident since there was a significant difference between experimental (0.86) and control rats (1.42). Low environmental temperature caused the development of EEF stunted and asynchronous, but no significant effect on the density of EEF in this group was found. The density and average diameter (AD) of EEF between rats illuminated 8 and 16 hours per day were identical. The interaction between splenectomy and elevated oestrogen level offset each other, whereas the interactions between other two factors showed no difference by analysis of variance.