Immunohistochemical examination of immune cells in adipose tissue of rainbow trout (Oncorhynchus mykiss) following intraperitoneal vaccination

• Published in: Fish & shellfish immunology Vol. 87; pp. 559 - 564
• Main Authors: Veenstra, Kimberly A., Alnabulsi, Ayham, Tubbs, Lincoln, Ben Arous, Juliette, Secombes, Christopher J.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.04.2019
• Subjects: Adipose tissue; APC; B-cell; Cell markers; Immunohistochemistry; Milky spots; Rainbow trout; T-cell; Vaccination; Immunohistochemistry; Adipose tissue; Milky spots; APC; T-cell; Cell markers; B-cell; Vaccination; Rainbow trout
• ISSN: 1050-4648; 1095-9947
• DOI: 10.1016/j.fsi.2019.02.001

Mammalian perivisceral adipose has been shown to play an important role in the regulation of the peritoneal immune responses. Recently it has been demonstrated that peritoneal antigens are collected by leukocytes within the visceral adipose mass, and a broad range of immunomodulatory genes are differentially expressed in adipose tissue after intraperitoneal vaccination in rainbow trout. To assess the immune cell component in adipose, immunohistochemical analysis was used to examine B-cell, T-cell and antigen presenting cell (APC) numbers and distribution in rainbow trout adipose tissue 24 and 72 h post vaccination in comparison to control fish. The results of this study support previous work on mammals with omental milky spots in naïve fish found to contain APCs and T-cells which then increased in size, number and complexity following vaccination. It suggests that following peritoneal stimulation the visceral adipose mass in fish likely plays an important role in vaccine antigen uptake and presentation by APCs, as well as subsequent T-cell activation and differentiation. •Milky spots in naïve rainbow trout contain APCs and T-cells.•Following vaccination milky spots increased in number, size and complexity.•Fish adipose may play a significant role in T-cell activation via APCs.