Effector functions of macrophages

Mononuclear phagocytes in head and neck squamous cell carcinoma

The head and neck squamous cell carcinoma microenvironments contain many immune cells and their secretory products. Many of these cells belong to the mononuclear phagocyte system. The aim of this review is to study the interactions between mononuclear phagocytes and head and neck squamous cell carcinoma tissue. The role of inflammation in tumours and the cytokine interleukin-6 will be highlighted. Future therapy strategies in the treatment of head and neck cancer might be directed towards mononuclear phagocytes and their cytokine production.

Characterization of receptors for platelet-activating factor on platelets, polymorphonuclear leukocytes and macrophages

1. We have compared the potency of the putative platelet-activating factor (Paf) receptor antagonists (WEB 2086, L-652,731 and BN 52021) against Paf-induced aggregation of rabbit and guinea-pig platelets, aggregation of rabbit polymorphonuclear leukocytes (PMNLs) and prostacyclin generation by guinea-pig resident peritoneal macrophages. 2. On rabbit washed platelets and PMNLs WEB 2086, L-652,731 and BN 52021 each antagonized competitively Paf-induced aggregation. The rank order of potency was WEB 2086 congruent to L-652,731 greater than BN 52021 and was the same for the two cell types. 3. The pA2 values for each of the three antagonists were similar on rabbit washed platelets and PMNLs. Moreover, the pA2 for WEB 2086 on rabbit platelets (7.58) did not differ significantly from that on guinea-pig platelets (7.69). 4. On guinea-pig resident peritoneal macrophages WEB 2086 was 10 fold less potent for receptors mediating increased generation of 6-oxo-prostaglandin F1 alpha (6-oxo-PGF1 alpha) than for those mediating platelet aggregation. 5. The potencies of L-652,731 and BN 52021 were also markedly less (2 log units) for the macrophage receptors than for platelet or PMNL receptors and BN 52021 was more potent than L-652,731 in the macrophages. 6. WEB 2086 and L-652,731 significantly reduced basal 6-oxo-PGF1 alpha produced by macrophages, but none of the antagonists affected 6-oxo-PGF1 alpha production during stimulation by A23187. 7. These data raise the possibility that there may be a Paf receptor-subtype mediating prostacyclin generation in macrophages that is different from that on the platelet and PMNL. Hence, the potency of Paf antagonists against platelet aggregation would not be a good predictor of antagonist potency in disorders involving macrophages.

Semisoluble aminated glucan: long-term efficacy against an intraperitoneal E. coli challenge and its effect on formation of abdominal adhesions

The first part of this study in the rat was designed to assess the immediate and, in particular, the long-term effects of semisoluble aminated glucan (SAG) with regard to an intraperitoneal (i.p.) E. coli challenge and side-effects. The severity of the E. coli peritonitis was evaluated by quantification of the concomitant bacteremia. The animals randomly received either 10 ml normal saline i.p. (controls) or 10 ml (50 mg) SAG i.p. (experimental groups). It was found that SAG had no immediate protective effect against the infectious challenge as no difference was detected in the bacterial clearance between saline- and SAG-treated rats at day 0. However, 2 days after injection of saline/SAG a substantial protection of SAG was noted as no blood-borne bacteria could be detected at 1, 2, 3, 4 and 5 h after the E. coli challenge in SAG-treated animals, whereas by contrast matching blood cultures were positive in all controls. A likewise protective effect against E. coli bacteremia of a single i.p. injection of SAG was demonstrated at 7, 21, and 49 days after the administration of the compound. During the 7-week experimental period no clinical side-effects of SAG were observed. At autopsy (days 0, 2, 7, 21, and 49, respectively) no gross pathologic conditions were found. Lung, spleen, and kidney sections from SAG-treated rats were normal, whereas tiny granulomas were exhibited in liver sections, possibly related to the hyperfunctional macrophage state which SAG induced. The second main object of the study was to evaluate SAG's effect on adhesion formation.(ABSTRACT TRUNCATED AT 250 WORDS)