Table 2 Description of key genes and functions.

IL2RB

Interleukin 2 Receptor Subunit Beta

The role of interleukin-2 receptors in T cell-mediated immune responses is manifested through three distinct forms based on their ability to bind interleukin-2.The low-affinity form consists of a single alpha subunit and does not participate in signal transduction. The intermediate-affinity form is composed of a heterodimer of α and β subunits, while the high-affinity form is composed of a heterotrimer of α, β, and γ sub units. Both the intermediate and high affinity forms of this receptor are involved in receptor-mediated endocytosis and the transmission of mitogenic signals of interleukin 2 by white blood cells. The utilization of distinct promoters leads to the generation of multiple transcript variants encoding the same protein. This protein is primarily expressed in the hematopoietic system. In certain variants, the utilization of another promoter within the long terminal repeats (LTRs) upstream can result in specific expression in the placenta.

KLRD1

Killer Cell Lectin Like Receptor D1

NK cells are a unique type of lymphocyte that can kill cells and release cytokines when the immune system is activated. NK cells express genes from the C-type lectin superfamily, such as those from the NKG2 family, which may play a role in controlling NK cell activity. The KLRD1 (CD94) antigen is preferentially expressed on NK cells and classified as a type II membrane protein due to its external C-terminus. Several transcript variants encoding different isoforms of this gene have been identified.

GZMB

Granzyme B

This gene encodes a member of the granzyme subfamily of proteins, part of the peptidase S1 family of serine proteases. The precursor protein of the encoding is secreted by natural killer cells (NK) and cytotoxic T lymphocytes (CTL), and upon protein hydrolysis, active proteases are generated, thereby inducing apoptosis in target cells. This protein is involved in the processing of cytokines and the degradation of extracellular matrix proteins, which are related to the pathogenesis of chronic inflammation and wound healing. Elevated expression of this gene may occur in patients with human cardiac fibrosis.

TBX21

T-Box Transcription Factor 21

This gene is a member of a conserved gene family in the evolutionary system which share a DNA binding ___domain known as the T-box. T-box genes encode transcription factors that regulate developmental processes. This gene is the human homolog of the mouse Tbx21/Tbet gene. Studies in mice have shown that the Tbx21 protein is a Th1 cell-specific transcription factor that regulates the expression of the Th1 cell signature cytokine, interferon-gamma (IFNG).Similarly, the expression of the same source material in humans is associated with the expression of IFNG in Th1 cells and natural killer cells, indicating the role of this gene in initiating the development of the Th1 lineage from immature Th precursor cells.

PRF1

Perforin 1

This gene encodes a protein that shares structural similarities with complement component C9, which plays a crucial role in immunity. This protein facilitates the formation of membrane pores, enabling the discharge of granzymes and subsequent cytolysis of target cells. The debate persists regarding whether the pore formation are formed on the plasma membrane of target cells or on the endoplasmic reticulum membrane within the target cells.

HAVCR2

Hepatitis A Virus Cellular Receptor 2

This gene encodes a protein that is a member of both the immunoglobulin superfamily and the TIM protein family. CD4-positive T helper lymphocytes can be classified into two distinct subtypes, designated as Th1 and Th2, based on their cytokine secretion profiles. T cells are vital in cellular immunity against intracellular pathogens and delayed-type hypersensitivity reactions, with Th1 cells playing a crucial role. Conversely, Th2 cells oversee extracellular worm infections and promote the emergence of atopic and allergic diseases. A cell surface protein specific to Th1 cells, this protein regulates macrophage activation, attenuates Th1-induced autoimmune and alloimmune reactions, and aids in immune tolerance.

GZMA

Granzyme A

Cells T lymphocytes (CTL) and natural killer cells (NK) both possess outstanding abilities to recognize, bind, and dissolve specific target cells. It is hypothesized that they protect the host by dissolving cells with “non-self” antigens on their surface, which are typically peptides or proteins produced by intracellular pathogens. The protein described here is a serine protease specific to T cells and natural killer cells, which may be a shared component required for cytotoxic T lymphocytes and natural killer cells to lyse target cells.