Thy-1 immunolabeled thymocyte microdomains studied with the atomic force microscope and the electron microscope

The atomic force microscope (AFM) and the transmission electron microscope (TEM) have been used to study the morphology of isolated mouse thymocyte microdomains and Thy-1 antigen distribution at the surface of these structures. AFM images were recorded in air in the contact mode on membrane vesicles deposited on previously heated tissue culture plastic sheets and indirectly immunolabeled for Thy-1 expression with colloidal gold-conjugated secondary antibodies. AFM images of untreated plastic plates showed a very characteristic network of streaks 20–200 nm wide. Heating the plastic removed the streaks and provided flat surfaces (r.m.s. 1 nm). This substrate allowed strong adsorption and homogeneous spreading of the vesicles and easy manipulations during immunolabeling experiments. Vesicles flattened on the substrate without losing their morphology. The 10-nm membrane-bound gold beads were reproducibly imaged without degradation by repeated tip scanning. The observed microdomains had a mean diameter of 184 +/- 76 nm, and 65% of them were specifically labeled. Images obtained with the TEM on the same vesicles, deposited on carbon-coated grids and negatively stained, confirmed the AFM observations. The size distribution of the microdomains was quite similar, but the number of beads per vesicle was significantly higher, and 76% of the vesicles were labeled. The difference may be explained 1) by removal of beads from the vesicles in the additional washing step with water, which was necessary for the AFM; 2) by tip-sample convolution; and 3) by statistical fluctuations

Combined curative radiation therapy alone in (T1) T2-3 rectal adenocarcinoma: a pilot study of 29 patients

International audienc

Immunociblage des tumeurs: situation et perspectives en 2000

Following 15 years of experimental studies, tumor immunotargeting using monoclonal antibodies directed against tumor associated antigens shows now important monoclonal antibodies directed against tumor associated antigens shows now important clinical developments. This is mainly due to encouraging therapeutic results which have obtained using humanized antibodies such as the anti-CD20 rituximab in follicular B lymphomas and the anti-DrbB2 herceptin in breast carcinomas. Thanks to genetic engineering it is possible to graft variable or hypervariable regions from murine antibodies to human IgG, and even to obtain fully human antibodies by using either transgenic mice containing a large part of the human repertoire of human IgG, or selection of human antibody fragments expressed by phages. Radiolabeling of antibodies played a major role to demonstrate the tumor immunotargeting specificity and remains attractive for the diagnosis by immunoscintigraphy as well as for the treatment by radioimmunotherapy of some cancers. In this review, the current results and the prospects of diagnostic and therapeutic uses of anti-tumor antibodies and their fragments will be described. Concerning diagnosis, 123-iodine or 99m-technetium labeled Fab fragments allowed very demonstrative tumor images but this technique has a limited effect upon the therapeutic attitude. Immuno-PET (positron emission tomography) could enhance the sensitivity of this imaging method. Radio-immunoguided surgery and immunophotodetection are attractive techniques still under evaluation. Concerning therapy, 131-iodine labeled anti-CD20 antibodies gave spectacular results in non-Hodgkin's B lymphomas. In solid tumors which as less radiosensitive, radioimmunotherapy could concern small tumors and need the use of two-steps targeting and/or alpha emitters radioisotopes. Some other strategies will be described such as bispecific antibodies directed against tumors and immune effector cells, some antibody fragments expressed on T cells called T-bodies or some biological studies using intrabodies. Published data and works in progress demonstrate that immunotargeting of tumors will have a growing place in the treatments of cancer patients