Identification of exposed components on the surface of adult Schistosoma mansoni by lactoperoxidase-catalysed iodination

Adult schistosomes have been labelled with ¹²⁵I using the lactoperoxidase-catalysed technique modified to cause minimal worm damage. After surface membrane removal and characterization, at least 13 labelled proteins were identified together with a large amount of labelled glycolipids, free fatty acids and phospholipids, especially phosphatidyl ethanolamine. Cationised ferritin has been used to stimulate surface membrane turnover of iodinated worms and the shedding of covalently bound ¹²⁵I-counts used as an index of turnover. Finally worms have been iodinated before and after stimulation of membrane turnover in chemically defined media and the patterns of labelled proteins were compared.     

Macrophage support and suppression in rabbit T cell mitogenesis

The role of macrophages in mitogen-induced rabbit T cell proliferation has been investigated. The blastogenic response to the 3 mitogens, PHA, ConA and oxidative treatment by neuraminidase and galactose oxidase (NaGo) was tested. T cell proliferation was reduced by removal of low density or plastic adherent cells, including macrophages, and could be enhanced by the addition of peritoneal resident macrophages, indicating a macrophage requirement for rabbit T cell proliferation. However, PHA-induced proliferation could not be raised to the level expected. It was found that catalase and especially 2-ME could considerably enhance macrophage dependent proliferation, even at low macrophage concentrations. It is concluded therefore, that macrophages not only support but also suppress lymphocyte proliferation, namely by non-specific damage to lymphocytes through release of radicals and hydrogen peroxide. In addition, peritoneal, but not lymph node macrophages were found to suppress lymphocyte proliferation by prostaglandin production, although to a lesser extent. Experiments, done in the presence of blockers of macrophage-mediated suppression, showed that macrophages were able to magnify the PHA-induced T cell proliferation to the expected values. The experiments thus show that unactivated macrophages support and suppress lymphocyte proliferation at the same time.