Self Reactive B Cells May Be Rescued by Editing of Light Chain Genes

Later work using the transgenic system described by Nemazee and Burki showed that negative selection of immature B cells does not always result in their immediate deletion (Figure 11-5c). Instead, maturation of the self-reactive cell is arrested while the B cell "edits" the light-chain gene of its receptor. In this case, the H-2d/k transgenics produced a few mature B cells that expressed mIgM containing the ^ chain encoded in the transgene, but different, endogenous light chains. One explanation for these results is that when some immature B cells bind a self-antigen, maturation is arrested; the cells up-regulate RAG-1 and RAG-2 expression and begin further rearrangement of their endogenous light-chain DNA. Some of these cells succeed in replacing the k light chain of the self-antigen reactive antibody with a X chain encoded by endogenous X-chain gene segments. As a result, these cells will begin to express an "edited" mIgM with a different light chain and a specificity that is not self-reactive. These cells escape negative selection and leave the bone marrow.

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Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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