Beschreibung:
<jats:title>Summary</jats:title><jats:p>Follicular helper T‐cells (Tfh cells) are a subset of <jats:styled-content style="fixed-case">CD</jats:styled-content>4<jats:sup>+</jats:sup> T‐cells that are essential for normal production of high affinity antibodies. Tfh cells characteristically produce <jats:styled-content style="fixed-case">IL</jats:styled-content>21 and <jats:styled-content style="fixed-case">IL</jats:styled-content>4 and show high expression of surface markers <jats:styled-content style="fixed-case">CXCR</jats:styled-content>5, <jats:styled-content style="fixed-case">ICOS</jats:styled-content>,<jats:styled-content style="fixed-case"> PDCD</jats:styled-content>1 (<jats:styled-content style="fixed-case">PD</jats:styled-content>‐1) and the chemokine <jats:styled-content style="fixed-case">CXCL</jats:styled-content>13. In this review we will focus on the emerging links between Tfh cells and subtypes of T‐cell non‐Hodgkin lymphoma: angioimmunoblastic T‐cell lymphoma (<jats:styled-content style="fixed-case">AITL</jats:styled-content>) and ~20% of peripheral T‐cell lymphoma not otherwise specified (<jats:styled-content style="fixed-case">PTCL</jats:styled-content>‐<jats:styled-content style="fixed-case">NOS</jats:styled-content>) have surface marker features of Tfh cells and share a spectrum of genetic abnormalities. The recurrent genetic abnormalities associated with <jats:styled-content style="fixed-case">AITL</jats:styled-content> include mutations in epigenetic modifiers such as <jats:styled-content style="fixed-case"><jats:italic>TET</jats:italic></jats:styled-content><jats:italic>2</jats:italic> and <jats:styled-content style="fixed-case"><jats:italic>DNMT</jats:italic></jats:styled-content><jats:italic>3A</jats:italic> and the motility and adhesion gene, <jats:styled-content style="fixed-case"><jats:italic>RHOA</jats:italic></jats:styled-content>, is mutated in up to 70% of cases. ~20% of <jats:styled-content style="fixed-case">PTCL</jats:styled-content>‐<jats:styled-content style="fixed-case">NOS</jats:styled-content> demonstrate <jats:styled-content style="fixed-case"><jats:italic>RHOA</jats:italic></jats:styled-content> mutations and have other characteristics suggesting an origin in Tfh cells. The recognition that specific genetic and surface markers are associated with malignant Tfh cells suggests that the next few years will bring major changes in diagnostic and treatment possibilities. For example, antibodies against <jats:styled-content style="fixed-case">IL</jats:styled-content>21, <jats:styled-content style="fixed-case">PDCD</jats:styled-content>1 and <jats:styled-content style="fixed-case">ICOS</jats:styled-content> are already in clinical trials for autoimmune disease or other malignancies and antibodies against <jats:styled-content style="fixed-case">CXCL</jats:styled-content>13 are in pre‐clinical development.</jats:p>