Naive CD4+ T Cells

Naive CD4+ T Cell Activation Through CD40L

Naive CD4+ T cells upregulate CD40L after interacting with CD70. CD70 is expressed on CD8+ T cells after interaction with dendritic cells. CD40L has a critical role during the priming phase of adaptive immune responses in lymph nodes (1, 2)

Naive CD4+ T Cell States and Gene Activity

Naive CD4+ T cells in mice are not uniform. They form several groups with distinct gene-activity patterns associated with:

• Cellular resting state


• Extracellular matrix and cytoskeleton biology


• Type I interferon responses


• Memory-like features


• T cell receptor activation
  This variation was similar in germ-free mice and mice with normal microbiota, indicating that it does not depend on commensal bacteria (3).

Helminth Infection Reprograms Naive T Cells

Infection with the helminth Nippostrongylus brasiliensis changed naive CD4^+^ T cell states and altered gene activity within these cells. These changes were associated with a weaker response to subsequent vaccination against an unrelated antigen (3).

The changes disappeared after the helminth infection was cleared, suggesting that environmental signals can temporarily reconfigure naive T cells and alter the strength of later immune responses (3).

TGF-Beta Drives Regulatory T Cell Differentiation

TGF-beta induced Foxp3 expression in TCR-challenged CD4+CD25− naive T cells. This promoted their transition toward a regulatory T cell phenotype with potent immunosuppressive activity (4).

References

(1) Luft et al. 2002
(2) Stuhler et al. 1999 Proc Natl Acad Sci USA 96: 1532
(3) Even et al. 2024 Immunity 57(8): 1893-1907
(4) Chen et al. 2003 J. Exp. Med. 198: 1875-1886