Immunotherapy (IT) has become an accepted therapeutic modality. We previously reported that intracellular hyperthermia (IH) using magnetic nanoparticles induces antitumor immunity. We undertook these studies in order to study the combined effects of IT and IH on melanoma. Magnetite cationic liposomes (MCLs) have a positive surface charge and generate heat in an alternating magnetic field (AMF) due to hysteresis loss. MCLs were injected into a B16 melanoma nodule in C57BL/6 mice, which were subjected to AMF for 30 min. The temperature at the tumor reached 43°C and was maintained by controlling the magnetic field intensity. At 24 h after IH, interleukin-2 (IL-2) or granulocyte macrophage-colony stimulating factor (GM-CSF) was injected directly into the melanoma. Mice were divided into six groups: group I (control), group II (IH), group III (IL-2), group IV (GM-CSF), group V (IH + + + +IL-2), and group VI (IH + + + +GM-CSF). yperthermia has been used for many years to treat a wide variety of tumors both in experimental animals and patients.1) The most commonly used heating method in clinical settings is capacitive heating using a radiofrequency (RF) electric field.2) However, specifically heating tumors by capacitive heating using an RF electric field is difficult, because the heating characteristics are influenced by various factors, such as tumor size, position of electrodes, and adhesion of electrodes at uneven sites. From a clinical point of view, a simple heat mediator is preferable for superficially seated tumors such as cutaneous melanoma. Magnetic nanoparticles have been applied to generate hyperthermia in an attempt to overcome these disadvantages.3, 4) These magnetic nanoparticles generate heat in an alternating magnetic field (AMF) due to hysteresis loss. 5)We have developed "magnetite cationic liposomes" (MCLs) for intracellular hyperthermia (IH).6, 7) MCLs were developed to show improved adsorption and accumulation in tumor cells and have a ten-fold higher affinity for tumor cells than for neutrally charged magnetoliposomes due to electrostatic interaction with the negatively charged cell membrane.6) In our in vitro experiments, 55% of MCLs were incorporated into cells and the intracellular magnetic nanoparticles could generate heat under AMF.6) We have also demonstrated the efficacy of IH using MCLs against T-9 rat glioma in an in vivo study. 8)We previously reported that our IH system induced antitumor immunity. 9) Hyperthermia is known to induce heat shock proteins (HSPs).10) Because expression of HSP70 protects cells from heat-induced apoptosis, 11) HSP70 expression has been considered to be a complicating factor in hyperthermia. On the other hand, recent reports have shown the importance of HSPs, such as HSP70, HSP90 and glucose-regulated protein 96, in immune reactions.12, 13) HSP-mediated antitumor immunity was reported to cause a vaccine effect due to HSP-peptide complexes purified from human melanoma cells.14) With regard to the mechanism of antitumor immunity induced by IH, we demonstrated th...

No abstract

The retinal pigment epithelium (RPE) of 1- 24-month-old CF-1 mice was examined by both light and electron microscopy. Measurement of the area occupied by lysosomal bodies was carried out using a semiautomatic quantitative picture analyzing system (Kontron-EKO). Accumulation of lysosomal bodies in the apical RPE cytoplasm was the most characteristic feature in eyes over 12 months of age. The relative volume of lysosomal bodies to each RPE cytoplasm was maximal in 24-month-old mice RPE, approximately three times that of 3-month-old mice. Complicated lysosomal bodies and small lysosomal bodies were also observed in the dilated microvilli, in the apices of the apical RPE cytoplasm and in the subretinal spaces in eyes over 18 months of age. The passway and extrusive mechanism of lysosomal bodies are discussed.

No abstract