No abstract

Cord blood and fetal liver B cells were immortalized using Epstein-Barr virus, and IgM antibodies from the resulting lines and clones were examined for their binding to a variety of auto-antigens and micro-organisms by ELISA and fluorescence assays. Auto-antigens tested included Fc of IgG, ssDNA and dsDNA, cardiolipin, histones 1-4, collagens type I and II, thyroglobulin, cytoskeletal components, and a tissue section screen. Of 71 cell lines tested, all but 19 showed some autoreactivity. All 32 fetal liver lines reacted to some self-antigens. In cord blood clones, 16 out of 26 bound to auto-antigens. Many of the clones reacted with more than one auto-antigen and were 'polyreactive'. Some of the cord blood clones bound to extracts of micro-organisms, showing specificity for both endogenous and exogenous antigens. The high frequency of CD5+ B cells in the cord blood (greater than 50%) and fetal liver (greater than 70%) argues for many of these clones being derived from this subset. Therefore, our data support the concept that many 'early' B cells produce polyreactive IgM which can bind to a variety of different auto-antigens and micro-organisms. These IgM antibodies are similar to those described by others as 'natural antibodies'.

Références Le portfolio en éducation des sciences de la santé : un outil d'apprentissage, de développement professionnel et d'évaluation

Messages-clés • Plusieurs courants conceptuels ont contribué graduellement à l' é l a b o ration des principes Key learning points • Se ve ral conceptual influences contributed gradually to elaborate the principles of the so-called "learn e r -c e n t e red para d i g m". These contributions are those of humanistic psyc h o l o gy, andra g o g i c t h e o ry, socio-cognitivist (or constructivist) theory and continuous quality improvement move m e n t .• The principles of the learn e r -c e n t e red paradigm emphasize contextualized competences, assessing them through pro f e ssional complete, complex and meaningful tasks and embedding evaluation within teaching and learning activities.• Such a conceptual fra m e w o rk seems part i c u l a rly fruitful for the development of a post-graduated pro g ram in medicine. An experiment concerning a curricular revision developed in a general medicine pro g ram is presented and illustra t e d .Key words l e a r n e r -c e n t e red paradigm ; general medicine ; internship.