Shaping the humoral immune response: Actin regulators modulate antigen presentation and influence B-T interactions.

B cells are an integral part of the adaptive immune system. During an immune response, the actin cytoskeleton plays a central role in regulating B cell antigen uptake, polarization and presentation as well as B cell migration and interaction with T cells. Genetic defects affecting actin regulators can result in reduced B cell activation, limited antibody production and hence cause disease.

The Lack of WIP Binding to Actin Results in Impaired B Cell Migration and Altered Humoral Immune Responses.

Wiskott-Aldrich syndrome protein (WASp) is a main cytoskeletal regulator in B cells. WASp-interacting protein (WIP) binds to and stabilizes WASp but also interacts with actin. Using mice with a mutated actin binding domain of WIP (WIPΔABD), we here investigated the role of WIP binding to actin during B cell activation.

A switch from canonical to noncanonical autophagy shapes B cell responses.

Autophagy is important in a variety of cellular and pathophysiological situations; however, its role in immune responses remains elusive. Here, we show that among B cells, germinal center (GC) cells exhibited the highest rate of autophagy during viral infection. In contrast to mechanistic target of rapamycin complex 1-dependent canonical autophagy, GC B cell autophagy occurred predominantly through a noncanonical pathway.

Wiskott-Aldrich Syndrome Interacting Protein Deficiency Uncovers the Role of the Co-receptor CD19 as a Generic Hub for PI3 Kinase Signaling in B Cells.

Humans with Wiskott-Aldrich syndrome display a progressive immunological disorder associated with compromised Wiskott-Aldrich Syndrome Interacting Protein (WIP) function. Mice deficient in WIP recapitulate such an immunodeficiency that has been attributed to T cell dysfunction; however, any contribution of B cells is as yet undefined. Here we have shown that WIP deficiency resulted in defects in B cell homing, chemotaxis, survival, and differentiation, ultimately leading to diminished germinal center formation and antibody production.

Signal 3 cytokines as modulators of primary immune responses during infections: the interplay of type I IFN and IL-12 in CD8 T cell responses.

Signal 3 cytokines, such as IL-12 or type I IFN, support expansion and differentiation of CD8 T cells in vivo. If and how these two signal 3 cytokines compensate each other in T cell activation during different infections is so far unknown. Using CD8 T cells lacking receptors for IL-12, type I IFN or both, we show that the expansion of CD8 T cells depends on type I IFN (LCMV infection), type I IFN and IL-12 (Listeria and vesicular stomatitis virus infection) or is largely independent of the two cytokines (vaccinia virus infection).