T helper (Th) cells are CD4⁺ lymphocytes that orchestrate adaptive immunity. CD4 stabilizes TCR–MHC II interactions and amplifies signaling [1], enabling naïve Th cells to differentiate into specialized subsets. As I illustrated in my Immunocards (https://lnkd.in/p/e6Jf-2HN) CD4⁺ T cell types. 

𝗦𝘂𝗯𝘁𝘆𝗽𝗲𝘀 𝗮𝗻𝗱 𝗖𝘆𝘁𝗼𝗸𝗶𝗻𝗲 𝗣𝗿𝗼𝗳𝗶𝗹𝗲𝘀 
𝘛𝘩1: IFN-γ, IL-2 → cell-mediated immunity, intracellular pathogens [2] 
𝘛𝘩2: IL-4, IL-5, IL-13 → humoral immunity, helminths, allergy [3] 
𝘛𝘩17: IL-17, IL-22 → neutrophil recruitment, mucosal defense [4] 
𝘛𝘳𝘦𝘨𝘴: IL-10, TGF-β → immune suppression, tolerance [5] 
𝘛𝘧𝘩: IL-21 → B cell help, germinal center formation [6] 
Other Th subsets (𝘛𝘩9, 𝘛𝘩22, 𝘛𝘳1, 𝘛𝘩𝘎𝘔, 𝘛𝘩𝘊𝘛𝘓): Specialized functions in tissue repair, immune regulation, or cytotoxicity [7] 

𝗣𝗹𝗮𝘀𝘁𝗶𝗰𝗶𝘁𝘆 & 𝗚𝗲𝗿𝗺𝗮𝗻 𝗥𝗲𝘀𝗲𝗮𝗿𝗰𝗵 
CD4⁺ T cells are 𝘩𝘪𝘨𝘩𝘭𝘺 𝘱𝘭𝘢𝘴𝘵𝘪𝘤: 𝘴𝘶𝘣𝘴𝘦𝘵𝘴 𝘤𝘢𝘯 𝘴𝘩𝘪𝘧𝘵 𝘱𝘩𝘦𝘯𝘰𝘵𝘺𝘱𝘦 depending on cytokine milieu, infection type, or tissue environment. 
Jochen Hühn (Helmholtz Centre for Infection Research) shows gut microbiota can induce regulatory features in Th17 cells [8]. 
Thomas Kamradt (University of Jena) studies how chronic infection cues influence Th differentiation and function [9]. 

𝗧𝗵𝗲𝗿𝗮𝗽𝗲𝘂𝘁𝗶𝗰 𝗜𝗺𝗽𝗹𝗶𝗰𝗮𝘁𝗶𝗼𝗻𝘀 
Pro-inflammatory Th17 or Th1 cells can be redirected toward Treg or less pathogenic phenotypes, reducing tissue damage in autoimmunity. Tolerogenic antigen presentation, cytokine modulation, or transcription factor targeting aim to suppress or reprogram self-reactive Th cells [10].  

𝗦𝗽𝗲𝗰𝘂𝗹𝗮𝘁𝗶𝘃𝗲 𝗛𝘆𝗽𝗼𝘁𝗵𝗲𝘀𝗶𝘀: ´𝗜𝗺𝗺𝘂𝗻𝗲 𝗦𝘆𝗺𝗽𝗵𝗼𝗻𝘆´ 
Th cells are using cytokine gradients as a ´score´ to coordinate innate and adaptive cells. Manipulating Th plasticity could therapeutically ´retune´ immune responses in autoimmunity or chronic infections.   

Stay tuned for 𝗗𝗮𝘆 𝟭𝟳: 𝗖𝘆𝘁𝗼𝘁𝗼𝘅𝗶𝗰 𝗧 𝗖𝗲𝗹𝗹𝘀 (𝗖𝗗𝟴+) – 𝗣𝗿𝗲𝗰𝗶𝘀𝗶𝗼𝗻 𝗔𝘀𝘀𝗮𝘀𝘀𝗶𝗻𝘀 𝗼𝗳 𝘁𝗵𝗲 𝗜𝗺𝗺𝘂𝗻𝗲 𝗦𝘆𝘀𝘁𝗲𝗺 

𝗥𝗲𝗳𝗲𝗿𝗲𝗻𝗰𝗲𝘀 
1. https://doi.org/10.1146/annurev-immunol-030409-101212 
2. DOI: 10.1016/s0092-8674(00)80702-3 
3. DOI:10.1038/nri2735 
4. DOI: 10.1038/ni1254 
5. DOI: 10.1038/cr.2016.151 
6. DOI: 10.1146/annurev-immunol-031210-101400 
7.  https://doi.org/10.1111/imr.12028 
8. https://www.helmholtz-hzi.de/en/research/research-groups/details/experimental-immunology/ 
9. DOI: 10.1084/jem.180.6.2069 
10. DOI: 10.1146/annurev.immunol.021908.132710   

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