Summary of Helper T Cells Function and Characteristics

Helper T Cells Overview

  • Types: Th1, Th2, Th17, TFH, Treg

CD4+ T Helper Cells

  • Require tertiary signal for activation

  • Induced by cytokines from innate response

Differentiation Cytokines

  • Cytokines involved:

    • IL-6, IL-12 (Th1)

    • IL-4 (Th2)

    • TGF-B (Treg)

    • IL-21 (TFH)

    • IL-23 (Th17)

Transcription Factors

  • Th1: T-bet

  • Th2: GATA3

  • Th17: RORYT

  • TFH: Bcl-6

  • Treg: FoxP3

Characteristic Cytokines by Type

  • Th1: IFN-Y, IL-2

  • Th2: IL-4, IL-5, IL-10

  • Th17: IL-17, IL-22

  • Treg: TGF-B, IL-10

  • TFH: IL-21

Th1 Function

  • Activates macrophages

  • Increases phagosome-lysosome fusion

  • Produces TNF-alpha, NOS, ROS

Th2 Function

  • Activates cellular and antibody responses to parasites

Th17 Function

  • Enhances neutrophil responses

TFH Function

  • Supports B cells in:

    • Affinity maturation

    • Somatic hypermutations

    • Isotype switching (IgG, IgA, IgE requiring T cells)

Treg Function

  • Prevents autoreactivity

  • Secretes inhibitory cytokines (IL-4, IL-10, TGF-B)

  • High CD25 expression (IL-2Rα)

  • Inhibits dendritic cell maturation and function (CTLA4, LAG3)