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Rainbow trout lymphoid organs: cellular effects of corticosteroids and anti-thymocyte serum
Abstract:
Cellular populations were studied in lymphoid organs of rainbow trout. Kidney appeared to be the most important organ by the number of cells harvested. A high percentage of peroxidase positive cells was measured in kidney, spleen and blood. The use of cortisone and rabbit anti-thymocyte serum showed differences in ratio of sensitive cells from different organs. In fish treated with steroids, cell depletion was verified in each organ but histologic lesions were observed only in thymus. Rabbit anti-thymocyte serum was cytotoxic for the quasi-totality of thymocytes while it destroyed only a part of kidney, spleen and blood cells. No correlations could be made between steroid sensitive cells and anti-thymocyte serum sensitive cells.
Insights
Rainbow trout lymphoid organs were analyzed, with the kidney showing the highest cell yield. Steroid and anti-thymocyte serum treatments revealed distinct cellular sensitivities across organs, particularly in the thymus.
Area of Science:
- Immunology
- Fish biology
- Cellular biology
Background:
- Lymphoid organs are crucial for immune responses in fish.
- Understanding cellular populations in rainbow trout is vital for aquaculture and disease resistance.
- Previous studies have not fully characterized the cellular composition and sensitivities in rainbow trout lymphoid organs.
Purpose of the Study:
- To investigate cellular populations in rainbow trout lymphoid organs.
- To determine the sensitivity of these cells to cortisone and rabbit anti-thymocyte serum.
- To compare cellular responses across different lymphoid tissues.
Main Methods:
- Cellular populations were harvested from kidney, spleen, thymus, and blood of rainbow trout.
- Peroxidase staining was used to identify specific cell types.
- Cortisone and rabbit anti-thymocyte serum were administered to assess cell depletion and sensitivity.
- Histological examination was performed on treated organs.
Main Results:
- The kidney yielded the highest number of cells among the studied organs.
- A significant percentage of peroxidase-positive cells were found in the kidney, spleen, and blood.
- Cortisone treatment led to cell depletion in all organs, but histological lesions were only observed in the thymus.
- Rabbit anti-thymocyte serum was highly cytotoxic to thymocytes but affected kidney, spleen, and blood cells to a lesser extent.
- No correlation was found between cortisone-sensitive cells and rabbit anti-thymocyte serum-sensitive cells.
Conclusions:
- The kidney is a primary site for cellular populations in rainbow trout.
- Different lymphoid organs exhibit varying sensitivities to immunosuppressive agents like cortisone and anti-thymocyte serum.
- The thymus appears particularly vulnerable to both steroid and antibody-mediated immune challenges in this species.
- These findings contribute to a better understanding of fish immunology and potential targets for immune modulation.