CD4: a vital player in the teleost fish immune system

Abstract

CD4 is a nonpolymorphic transmembrane glycoprotein molecule that is expressed on the surface of T-helper cells and plays an essential role in the immune response. It functions as a coreceptor with the T-cell receptor by binding to major histocompatibility complex class II on the surface of dendritic cells that present antigens. CD4+ T cells hold a key position in coordinating the immune system through production of several cytokines after activation and differentiation. The CD4+ T helper subtypes (T-helper 1, T-helper 2, T-helper 17, T-helper 9, and regulatory-T cells) perform different immune functions subsequent to their differentiation from the naive T cells. Different types of CD4+ T cells require different cytokines such as drivers and effectors, as well as master transcription factors for their activation. Fish cells that express CD4-related genes are activated in the presence of a pathogen and release cytokines against the pathogen. This review highlights the types of CD4+ T cells in fish and describes their direct role in cell-mediated and humoral immunity for protection against the intracellular bacterial as well as viral infections in fish.

Growth performance, immune response and disease resistance of rainbow trout (Oncorhynchus mykiss) fedThymus vulgarisessential oils

“…Also, the immune genes of C3 and CD4 in all treated trout were significantly upregulated during 2 months trail, but their regulation was higher in fish fed higher dosage of thyme oils. It has been suggested that CD4 T helper cells are the homologue of those of mammalians, providing a protective response against the intracellular pathogens including bacteria, fungi, and protozoa (Ashfaq, Soliman, Saleh, & El‐Matbouli, ), and are effective against the intracellular antigens causing the release of IFNγ and IL‐2 (Luckheeram, Zhou, Verma, & Xia, ). Also, C3 protein plays a crucial role in complement activation and it is required for activation of both classical and alternative pathways.…”

Identification and Regulation of Interleukin-17 (IL-17) Family Ligands in the Teleost Fish European Sea Bass

“…Fish are the first group in the animal evolution that possess both innate and adaptive immunity. Fish show Th cells (CD4 + ), and functional and genomic studies greatly suggest that fish possess very similar populations of Th cells compared to humans, though they might be less evolved [6]. Regarding the Interleukin-17 (IL-17) cytokine family, up to seven IL-17 ligands have been identified in several fish species, including rainbow trout (Oncorhynchus mykiss) [7,8], Atlantic salmon (Salmo salar) [9,10], zebrafish (Danio rerio) [11], fugu (Takifugu rubripes) [12], medaka (Oryzias latipes) [13], channel catfish (Ictalurus punctatus) [14], miiuy croaker (Miichthys miiuy) [15], common carp (Cyprinus carpio) [16,17], yellow croaker (Larimichthys crocacea) [18], grass carp (Ctenopharyngodon idella), [19,20] and Siberia sturgeon (Acipenser baerii) [21].…”

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“…22 Helper T cells (CD4+T cells) and Treg cells participate in the immune balance of the body. [23][24][25] Th17 (CD4 + IL-17 + ) is a kind of CD4 + T cells secreting IL-17 is an important pro-inflammatory cytokine, which can stimulate the production of various inflammatory cytokines, such as IL-6, IL-8 and VCAM-1. CD4 + IL-10 + is a regulator T cell that can secrete anti-inflammatory cytokine IL-10.…”