A two-step, two-signal model for the primary activation of precursor helper T cells

TLDR

Current models of T helper cell activation fail to explain how the immune system discriminates peripheral self‑antigens from foreign antigens, a process that normally prevents responses to organ‑specific self‑antigens. The study proposes a new two‑step, two‑signal model for the primary activation of precursor helper T cells. The authors introduce a two‑step, two‑signal activation pathway that defines how precursor helper T cells become activated. Observations show that the immune system learns not to react to early‑appearing extrathymic self‑antigens, and the proposed model aligns with these findings by incorporating peripheral self‑nonself discrimination.

Abstract

I present here a new model for the primary activation of precursor helper T cells. Observations demonstrate that the immune system learns not to respond to extrathymic, organ-specific self-antigens because of their early appearance in development. The immune system thus discriminates between peripheral self-antigens and foreign antigens and, when mature, usually makes an immune response against only the latter. Contemporary models for the activation and inactivation of T helper (Th) function do not account for such discrimination. The model proposed here is consistent with contemporary findings and incorporates a mechanism of peripheral self–nonself discrimination.