Question

Approximately 98% of thymocytes undergo negative selection, whereas approximately only 60% of B cells undergo negative selection, in part due to receptor editing. Why would it be advantageous from the standpoint of self-tolerance for negative selection of developing T cells to be more stringent than negative selection of developing B cells? (Hint: think about cognates)

Answer 1

This is because B cells require the help of Th( T helper) cells for their antigenic reactions. As T cells undergo extremely stringent selection criteria while developing in thymus. And, approximately 98% of T cells undergo negative selection and this wastefulness is not needed again as strictly for B cells because they require the support of Th cells for their activity. As self reactive T cells have been eliminated, consequently, self reactive B cells are apparently harmless.

Therefore negative selection during B cell development need not to be that much stringent.