CD4: a vital player in the teleost fish immune system

Area of Science:

• Immunology
• Fish Biology
• Cellular Immunity

Background:

• CD4 is a transmembrane glycoprotein on T-helper cells, vital for immune response.
• CD4+ T cells coordinate immunity via cytokines and differentiation into subtypes like Th1, Th2, Th17, Th9, and Treg.
• These cells require specific cytokines and transcription factors for activation.

Purpose of the Study:

• To review CD4+ T cell subtypes in fish.
• To describe their role in cell-mediated and humoral immunity.
• To highlight their importance in protecting fish against intracellular bacterial and viral infections.

Main Methods:

• Literature review of CD4+ T cell functions in fish.
• Analysis of CD4-related gene expression and cytokine release in fish cells.
• Synthesis of information on T-helper cell differentiation and immune functions.

Main Results:

• Fish CD4+ T cells, similar to mammals, differentiate into distinct subtypes.
• These subtypes are activated by pathogens and release cytokines.
• CD4+ T cells play a direct role in both cell-mediated and humoral immunity in fish.

Conclusions:

• CD4+ T cells are critical for adaptive immunity in fish.
• Understanding fish CD4+ T cell subtypes aids in disease resistance strategies.
• This review provides insights into fish immune defense mechanisms against pathogens.