Targeting gene function in germinal center B cells: A practical approach

The germinal center (GC) reaction represents an essential phase of an adaptive immune response. Dysfunction of GC B cells can lead to life-threatening diseases including autoimmune disorders, lymphomas, and opportunistic infections. Defining the molecular circuitries controlling GC B cell physiology is crucial to understand the pathogenesis of GC B cell disorders, as well as to develop improved vaccines against foreign pathogens. Conditional gene targeting based on the Cre/loxP recombination system has substantially accelerated our comprehension of the genetic networks controlling GC B cell function. Several independent studies in the past 10 years have highlighted the many advantages and the few limitations and pitfalls associated to conditional gene manipulation in GC B cells using the Cre/loxP recombination system. Here, we describe the basic features of GC B cell-specific gene targeting experiments. We provide indications on the type of Cre transgene and controls to be chosen, way-out strategies to overcome leakiness of the Cre/loxP system, and approaches to minimize the number of experimental animals and to speed up analyses on conditional mutant GC B cells.