Monoclonal antibody AMH152 reacts with human monocytes in culture and with inflammatory macrophages

Cytotoxicity studies of Dynasan 114 solid lipid nanoparticles (SLN) on RAW 264.7 macrophages—impact of phagocytosis on viability and cytokine production

Solid lipid nanoparticles (SLN) based on Dynasan 114 (D114) were tested using RAW 264.7 cells. The influence of different surfactants on the cytotoxicity of this type of SLN was examined, expressed as 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) viability and the production of cytokines such as interleukin 6 (IL-6), IL-12 and tumour necrosis factor-α (TNF-α). Results were compared with previously obtained data when peritoneal mouse macrophages were used. SLN produced with stabilizers/surfactants such as poloxamer 188, sodium cholate, Lipoid S75, Tween 80, Poloxamine 908 and sodium dodecylsulfate were shown to be nontoxic towards RAW 264.7 cells. Cytokine production was reduced and stimulation, expressed in elevated cytokine levels, could not be found. Using cetylpyridinium chloride (CPC) as stabilizing surfactant, SLN became cytotoxic in a concentration-dependent manner. Not only were the viabilities reduced but also cytokine production. Cytotoxic effects of CPC stabilized SLN could be antagonized using cytochalasin B to block phagocytosis. D114-SLN produced with pharmaceutically accepted surfactants for intravenous injection (poloxamer 188, Lipoid S75, sodium cholate, Tween 80) were very well tolerated by the cells. Even sodium dodecylsulfate-stabilized D114-SLN did not exert toxic effects. Comparison of the RAW 264.7 data with previously obtained data from toxicity studies of D114-SLN towards peritoneal mouse macrophages showed similar results. This offers the possibility of using the RAW 264.7 cell line for cytotoxicity studies of colloidal drug carrier systems, rather than using laboratory animals as source of macrophages for these kinds of studies.

Immunohistochemical characterization of alveolar macrophages and pulmonary giant cells in fatal asphyxia

It is in dispute whether the occurrence of numerous alveolar macrophages and in particular pulmonary giant cells in cases of fatal asphyxia is associated with agonal activation and proliferation. The nature of these alveolar cells was investigated in selected fatalities with protracted final oxygen lack using immunohistochemistry (APAAP method) and a semi-quantitative graduation. The study included opiate-involved deaths (n = 22), fatal strangulations (n = 10) and a control group of sudden cardiovascular deaths (n = 10). Positive immunohistochemical reactions were observed with the monoclonal antibodies PG-M1 (general marker of macrophages, detection of nearly 100% of pulmonary macrophages and giant cells in all subgroups) and 25 F 9 (late stage inflammation marker, detection of pulmonary macrophages/giant cells in 70%/50% of opiate-involved fatalities, 70%/20% of strangulations and 40%/30% of control cases). The antibodies LN-4 (macrophages), 27 E 10 (early stage inflammation marker), AMH 152 (activated macrophages) and MIB 1 (proliferation marker) did not react with these cell populations.

CONCLUSIONS

pulmonary giant cells and numerous alveolar macrophages are not restricted to asphyxia. Their appearance is not of pathognomonic value for this diagnosis. Both cell types seem to be of heterogeneous nature (different functional state) as only one marker was expressed by all cells. The results do not suggest prefinal immigration, mobilization or proliferation of alveolar cells, but rather point to a longer pre-existence of macrophages and giant cells in pulmonary tissue (25 F 9 as late stage inflammation marker positive).

Internalization of human macrophage surface antigens induced by monoclonal antibodies

Drugs intended to be endocytosed by macrophages may be transported by MAbs directed against these cells. Twenty MAbs were investigated for this purpose. The binding of these MAbs to macrophages obtained from a 7 day culture of blood monocytes showed that anti-CD11b and anti-CD14 recognized the highest number of cell surface antigen sites. Further assays determined that anti-CD63, Mo5 and anti-CD33 were the MAbs that induced the strongest modulation of the corresponding antigens, the highest rate being with anti-CD63. Endocytosis of antigen-antibody complexes was evidenced by the presence of MAbs in the cytoplasm. Anti-CD63 MAbs induced the highest internalization in this assay. For most MAbs, however, the density of antigen sites and the intensity of antigen modulation were not predictive of the amount of MAb detected in the cytoplasm.