T Follicular Helper Cell Heterogeneity

T follicular helper (Tfh) cells specialize in helping B cells and are therefore critical contributors to the generation of humoral immunity. Tfh cells aid immunoglobulin class-switch recombination and support the germinal center response, thereby promoting immunoglobulin affinity maturation and the generation of humoral immune memory. Although their primary function is to promote B cell responses, Tfh cells also display phenotypic and functional diversity determined by the immunological and spatial contexts from which they emerge. We review recent advances in understanding the heterogeneity within Tfh cell subsets along with their differentiation and migratory trajectory, the phenotypes they adopt, their ontological relationships with one another, and their function in their respective environments.