Germinal centers (GCs) are regions in our lymph nodes where B cell lymphocytes proliferate, produce antibodies, and undergo selection in order to stage an immune response against invaders. There are two regions within the GCs – the light zone and the dark zone – and a recent paper clarifies the different roles of these regions in B cell division and selection. Victora and colleagues used a photactivatable green fluorescent protein (PA-GFP) in germinal centers and photactivated certain regions of cells. By tracking the dynamics of the green fluorescent signal, they were able to understand the roles of the different regions within the GC. Image is of a mouse lymph node before (left) and after (right) photoactivation of a cleverly selected region (“GFP”).
BONUS!! Cool movies of photoactivated regions found here.
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