By means of radioisotope technique the influence of azathioprine on humoral defence factors against E. coli was studied on germfree and ex-germfree rats monocontaminated with E. roli. Using inactivated sera, by the addition of serum from germfree rats as a source of complement, titration of antibodies showed that the bactericidal activity of serum from azathioprine-treated rats was reduced in relation to control serum. By distinguishing the immunoglobulins on the basis of their sensitivity to 2-rnercaptoethanol, it was found that azathioprine blocked the production of 2-mercaptoethanol-resistant antibodies. The complement activity in the azathioprine-treated animals was not found to be decreased. Apart from complement other non-specific humoral factors against E. coli did not seem to par-Received 15.vi.73
A method to be used for in vitro assay of the elimination of ingested 32P‐labelled E. coli from rat PMN monolayers has been evaluated. The rate of expulsion of bacterial label from phagocytes into the extracellular medium was found to range between 40 and 50 per cent of the total uptake 180 min after termination of ingestion. Serum enhanced the cellular uptake of bacteria, but did not affect the rate of elimination. Disintegration of the phagocytes was not found to be a problem.
The in uitro influence of methylprednisolone and hydrocortisone on rat humoral defence factors against E. coli was evaluated by means of radioisotope technique using :{?P-labelled E. coli. The opsonic activity of serum was studied by measuring uptake of bacteria by glass-adherent polymorphonuclear neutrophils from rats. The drug influence on bacteria and phagocytes was also evaluated. Pre-incubation of phagocytes with methylprednisolone did not reduce the cellular uptake, and pre-incubation of bacteria with this drug did not affect the rate of release of label from bacteria. Concentrations of methylprednisolone higher than 1 mg per ml blocked the opsonic and bactericidal activities of serum, and this effect was independent of pre-incubation.
Baardsen, A., Midtvedt, T. & Trippestad, A. Influence of methylprednisolone and azathioprine on polymorphonuclear neutrophils (PMN) and lymphocytes in germfree, monocontaminated and conventional rats. Acta path. microbiol. scand. Sect. C, 83: 210-214, 1975. In rats, protracted administration of methylprednisolone at high dose levels 1 ) increased the number of circulating PMN in germfree, monocontaminated (with Escherichia coli) and conventional rats. This drug-induced increase was more than doubled in the presence of microorganisms, as compared to germfree rats. 2) reduced the number of circulating lymphocytes more strongly in germfree rats than in monocontaminated and conventional rats. Protracted administration of azathioprine at high dose levels 1) reduced the number of circulating PMN in conventional rats, but not in germfree and monocontaminated rats. 2) did not affect the lymphocyte count at the dose level 40 mg per kg per day in any of the three groups of animals investigated.
Baardsen, A. Influence of hydrocortisone on uptake and elimination of 3ZP-labelled E. coli by rat polymorphonuclear neutrophils (PMN) in uitro. Acta path. microbiol. scand. Sect. C, 84: 131-134, 1976. Hydrocortisone was tested for inhibition of uptake and of elimination of E. coli by monolayers of rat peritoneal PMN. 32P was used as label of the bacteria and their degradation products eliminated from the phagocytes. The cellular uptake was reduced by hydrocortisone (1-2 mg per ml) both in the presence and absence of serum, while the elimination of bacterial label was reduced by 0.5 mg per ml and higher concentrations of the drug.
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