No abstract

The exopolysaccharide (EPS) of Pseudomonas aeruginosa was found to significantly inhibit neu-trophil random movement, chemotaxis and degranulation at concentrations as low as 0.3 μg/ml. Neutrophil adherence, respiratory burst and bactericidal capacity were inhibited by EPS concentrations of ≥ 3 μg/ml. Similarly, mitogen-induced lymphocyte transformation was more sensitive to the inhibitory effects of EPS than natural-killer cell cytotoxicity. These results cannot be explained by simple mechanical blockade, as additions of EPS as late as 48 h after the initiation of lymphocyte cultures still resulted in a significant inhibition of lymphocyte transformation. However, the inhibitory effects of EPS can be reversed by extensive washing of treated lymphocytes. These results suggest that the propensity of mucoid P. aeruginosa to persist in cystic fibrosis may be explained in part by the ability of EPS to interfere with host immunity.

Summary Bronchoalveolar lavage samples were collected using a fibreoptic endoscope from horses at specified times before and after single bouts of exercise. Lucigenin‐dependent phagocytic chemiluminescence was used to assess the effect of exercise on the alveolar macrophage metabolic activity in response to stimulation by opsonised zymosan. A profound suppressive effect on the chemiluminescence production was present throughout the first three days after exercise. However, the cellular composition of lavage fluids was not altered by the exercise. It is suggested that strenuous exercise may jeopardise the antimicrobial function of alveolar macrophages which may lead to an increase in susceptibility to infection.