First demonstration of antigen induced cytokine expression by CD4-1⁺ lymphocytes in a poikilotherm: Studies in Zebrafish (Danio rerio)
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Yoon, S., Mitra, S., Wyse, C., Alnabulsi, A., Zou, J., Weerdenburg, E. M., … Bird, S. (2015). First demonstration of antigen induced cytokine expression by CD4-1⁺ lymphocytes in a poikilotherm: Studies in Zebrafish (Danio rerio). PLOS ONE, 10(6), e0126378–e0126378. http://doi.org/10.1371/journal.pone.0126378
Permanent Research Commons link: https://hdl.handle.net/10289/9450
Adaptive immunity in homeotherms depends greatly on CD4+ Th cells which release cytokines in response to specific antigen stimulation. Whilst bony fish and poikilothermic tetrapods possess cells that express TcR and CD4-related genes (that exist in two forms in teleost fish; termed CD4-1 and CD4-2), to date there is no unequivocal demonstration that cells equivalent to Th exist. Thus, in this study we determined whether CD4-1⁺ lymphocytes can express cytokines typical of Th cells following antigen specific stimulation, using the zebrafish (Danio rerio). Initially, we analyzed the CD4 locus in zebrafish and found three CD4 homologues, a CD4-1 molecule and two CD4-2 molecules. The zfCD4-1 and zfCD4-2 transcripts were detected in immune organs and were most highly expressed in lymphocytes. A polyclonal antibody to zfCD4-1 was developed and used with an antibody to ZAP70 and revealed double positive cells by immunohistochemistry, and in the Mycobacterium marinum disease model CD4-1⁺ cells were apparent surrounding the granulomas typical of the infection. Next a prime-boost experiment, using human gamma globulin as antigen, was performed and revealed for the first time in fish that zfCD4-1⁺ lymphocytes increase the expression of cytokines and master transcription factors relevant to Th1/Th2- type responses as a consequence of boosting with specific antigen.
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© 2015 Yoon et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.