SummaryTo assess the role of different types of antigen-presenting cells (APC) in the induction of tolerance, we isolated B cells, macrophages, and dendritic cells from thymus and spleen, and injected these into neonatal BALB/c mice across an Mls-1 antigenic barrier. One week after injection of APC from Mls-I-incompatible mice or from control syngeneic mice, we measured the number of thymic, Mls-1'-reactive, Vs6+ T cells and the capacity of thymocytes to induce a graft-vs .-host (GVH) reaction in popliteal lymph nodes of Mls-1' mice. Injection of thymic but not spleen B cells deleted thymic, Mls-1'-reactive Vs6+ T cells and induced tolerance in the GVH assay. The thymic B cells were primarily of the CD5+ type, and fluorescence-activated cell sorter-purified CD5+ thymic B cells were active. Injection of dendritic cells from spleen or thymus also induced tolerance, but the Vs6 cells were anergized rather than deleted . Macrophages from thymus did not induce tolerance. Dendritic cells and thymic B cells were also effective in inducing tolerance even when injected into Mls -, major histocompatability complex-incompatible, I-E -mice, but only thymic B cells depleted V06-expressing T cells . Therefore, different types of bone marrowderived APC have different capacities for inducing tolerance, and the active cell types (dendritic cells and CD5+ thymic B cells) can act by distinct mechanisms .

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Reirradiation is considered to contribute to salvage in selected patients with relapsed non-small-cell lung cancer. Patients with a long interval after the initial irradiation are good candidates for reirradiation. On the other hand, patients with Eastern Cooperative Oncology Group (ECOG) performance status 3 were not good candidates.

Since patients treated with chemoradiotherpy using docetaxel showed better OS and distant metastasis-free rates than those who did not receive docetaxel, it was warranted to continue use of docetaxel. In chemoradiotherapy at a dose of 70 Gy using docetaxel, 2-year in-field control rate was 67%.

Enhancement features of lipoma and liposarcoma were well visualized on fat-suppressed T1-weighted images after Gd-DTPA administration. The septum-like structures of liposarcoma are thick and enhanced considerably, while septa of lipoma are thin and enhanced only slightly. Pathologically, the septum-like structures of liposarcoma contained muscle fibers and the septa of lipoma represented fibrous capsule. Identification of well-enhanced septa in a predominantly lipomatous tumor helps to differentiate malignant tumors from lipomas. As the septum-like structures of liposarcoma contain a skeletal muscle component the tumor might need more extensive surgical procedures including resection of adjacent muscles.

We propose a new method for analyzing the direct impact of multi-leaf collimator (MLC) leaf position errors on dose distributions in volumetric modulated arc therapy (VMAT). The technique makes use of the following processes. Systematic leaf position errors are generated by directly changing a leaf offset in a linac controller; dose distributions are measured by a two-dimensional diode array; pass rates of the dose difference between measured planar doses with and without the position errors are calculated as a function of the leaf position error. Three different treatment planning systems (TPSs) were employed to create VMAT plans for five prostate cancer cases and the pass rates were compared between the TPSs under various leaf position errors. The impact of the leaf position errors on dose distributions depended upon the final optimization result from each TPS, which was explained by the correlation between the dose error and the average leaf gap width. The presented method determines leaf position tolerances for VMAT delivery for each TPS, which may facilitate establishing a VMAT quality assurance program in a radiotherapy facility.

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