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Chromosomal translocations involving immunoglobulin switch regions are commonly thought to arise from aberrant AID-induced DNA lesions. New data, however, suggest AID does not initiate such lesions, but acts subsequently in the B cell transformation process.
Engagement of CD28 by B7 molecules results in the activation of T cells. In addition to this T cell stimulation through CD28, the engagement of B7 on dendritic cells by CD28 can lead to the activation of dendritic cells.
Mature dendritic cells are considered terminally differentiated. However, this dogma is challenged by data showing culture-generated mature dendritic cells can further differentiate under the influence of stromal cells.
Many models have been put forth to explain the function of CD4 T cell help in primary and memory CD8 T cell generation. New evidence suggests the licensing model may be the most physiologically relevant.
How innate immunity discriminates between noninvasive bacterial pathogens and commensals is unclear. The finding that epithelial cells recognize peptidoglycan fragments of Helicobacter pylori delivered by the type IV secretion system suggests an intriguing solution.
Dendritic cells at mucosal surfaces represent one of the first lines of immune recognition between the body and environmental pathogens and antigens. A meeting in July 2004 presented the latest understanding in the field.