Macrophage disappearance reaction in Rana esculenta induced by specific antigen and rabbit lymphokines.

Macrophage disappearance reaction was induced by intraperitoneal injections of specific antigens in Rana esculenta sensitized by bovine gamma globulin and Mycobacterium bovis BCG. Rabbit lymphokines derived from concanavalin A stimulated blood lymphocytes injected intraperitoneally were able to induce macrophage disappearance reaction in normal Rana esculenta. This suggests that mammalian lymphokines are capable of acting in amphibia. Mammalian lymphokines have not an exclusive class-specificity in vertebrates.     

Macrophage activation induced by a synthetic antioxidant

The effect of a synthetic antioxidant 2-tretbutyl-3-hydroxypyridine (TBHP) on the function of murine peritoneal macrophages (MP) has been studied. A direct contact of TBHP with MP in vitro increased the activity of a key enzyme of glucose monophosphate graft--glucose-6-phosphate dehydrogenase and the proportion of flattened MP. as compared to the control. Upon intraperitoneal MP injection the number of MP's in the abdominal cavity of mice increased. They differed from control MP's in enhanced flattening and phagocytosis. In mice with preinduced defect of abdominal clearance TBHP contributed to the recovery of the normal level of antibacterial protection. In all the in vitro and in vivo tests studying its activating effect on MP, the synthetic antioxidant was not inferior to the standard MP activator--bacterial lipopolysaccharide.     

Macrophage intracellular signaling induced by Listeria monocytogenes

Macrophages are critical for control of Listeria monocytogenes infections; accordingly, the interactions of L. monocytogenes with these cells have been intensively studied. It has become apparent that this facultative intracellular pathogen interacts with macrophages both prior to entry and during the intracellular phase. This review covers recent work on signaling induced in macrophages by L. monocytogenes, especially intracellular signals induced by secreted proteins including listeriolysin O and two distinct phospholipases C.     

Macrophage to dendritic cell transitioning induced by Toxoplasma

Toxoplasma gondii exploits the migratory properties of monocytes and dendritic cells to promote tissue dissemination. Recently, ten Hoeve et al. reported that the parasite effector protein GRA28 conspires with host chromatin modifiers to confer dendritic cell-like features that convert sessile macrophages into migratory cells that transport infection to distal organs.     

Origin and mediation of secretion induced by oral phytohaemagglutinin (PHA) in rats

After oral administration several gut-binding lectins induce accumulation of liquor and amylase in the proximal small intestine. Orally administered Phaseolus vulgaris phytohaemagglutinin (PHA) was used to study the mediation of these effects in rats. The regulation of amylase secretion clearly differed from that of the liquor. The amylase activity was of pancreatic origin, in agreement with the known cholecystokinin-releasing effect of PHA. It appears that CCK exerts its effect both directly and by facilitating neural stimulatory pathways. Intestinal secretion was identified as the source of the liquor, without a contribution by other secretions. It was mediated by a local cholinergic reflex with the involvement of both muscarinic and nicotinic acetylcholine receptors. It is speculated that the observed enteric reflex may enable the gut to transport secreted antibacterial peptides or secretory antibodies from the crypts to adherent bacteria on adjacent villi.     

Approach to the mechanism of Zajdela's hepatoma cell growth inhibition induced by concanavalin A and phytohaemagglutinin

Cell growth of tumour ascites cells was inhibited by concanavalin A, phytohaemagglutinin and Ricinus lectin at 2-100 micrograms/ml. As expected, the Ricinus lectin inhibited the protein synthesis estimated by leucine incorporation and decreased thymidine incorporation, whereas concanavalin A and phytohaemagglutinin stimulate the uptake and the incorporation of both leucine and thymidine, and thus, synthesis of protein and DNA. These results suggest that different mechanisms are involved in the hepatoma cell growth inhibition by the lectins. This difference was not related to the kinetic characteristics of the lectin interactions with the cells which represent a first and necessary step. It was showed that concanavalin A and phytohaemagglutinin as well as chloroquine inhibited the 14C-labelled asialofetuin degradation. We can conclude that Ricinus lectin present a toxic effect whereas both concanavalin A and phytohaemagglutinin show an anti-protease activity.