Abstracts (complete list) - Wissenschaft Online

Elena Babich, Ata-Ur Rasheed, Hans-Peter Rahn, Martin Lipp, Gerd Müller
Tracking follicular B helper T cell differentiation and function
by gene expression analysis
T cell-dependent immune responses are associated with the development of germinal
centers in which antigen-specific B cells differentiate into memory B cells and highaffinity
antibody-secreting plasma cells. The germinal center reaction critically depends
on the presence of follicular B helper T (TFH) cells, a specialized subset of CD4 T cells
providing B cell help. TFH cells have been initially identified by expression of the
chemokine receptor CXCR5, which guides these cells into follicles, and their ability to
efficiently induce immunoglobulin secretion by germinal center B cells. In addition, TFH
cells control affinity maturation and isotype switching of germinal center B cells. We
have recently shown that the differential expression of CXCR5 and the co-stimulatory
molecule ICOS defines subsets of tonsillar CD4 T cells that differ in their stimulatory
capacity, proliferative capacity and susceptibility to apoptosis. Our results suggest that
in humans follicular B helper T cell activity is confined to CXCR5(hi)ICOS(hi) CD4 T
cells. To more precisely define the differentiation pathway and molecular mechanisms
mediating essential physiological and pathophysiological functions of TFH cells we have
now extended our gene expression analysis and functional characterization of CD4 T cell
subsets. In this connection we are particularly interested in better understanding the
relationship of CXCR5 expressing CD4 T cells in the periphery and in lymphoid tissues as
well as the role of TFH cells in the pathophysiology of chronic inflammatory and
autoimmune diseases.