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Elevation of feline interleukin 6-like activity in feline immunodeficiency virus infection
T Ohashi1, R Goitsuka, T Watari
1Department of Veterinary Internal Medicine, Faculty of Agriculture, University of Tokyo, Japan.
Insights
Feline immunodeficiency virus (FIV) infection in cats is linked to increased feline interleukin 6 (IL-6)-like activity. This overproduction of IL-6 may drive polyclonal B-cell activation, a common issue in FIV-infected felines.
Area of Science:
- Veterinary Immunology
- Virology
- Immunology
Background:
- Feline immunodeficiency virus (FIV) infection is associated with hypergammaglobulinemia and polyclonal B-cell activation.
- Interleukin 6 (IL-6) is crucial for B-cell differentiation into immunoglobulin (Ig)-secreting cells.
Purpose of the Study:
- To investigate the role of feline IL-6-like activity in polyclonal B-cell activation during FIV infection.
- To determine if FIV infection elevates plasma IL-6 levels and influences IL-6 production by peripheral blood mononuclear cells (PBMC).
Main Methods:
- Assessed proliferative responses of hybridoma cell clone B3B1.
- Measured plasma IL-6-like activity and Ig concentrations in FIV-infected and healthy cats.
- Cultured PBMC from FIV-infected and healthy cats to quantify IL-6 production.
Main Results:
- FIV-infected cats exhibited hypergammaglobulinemia, characterized by increased gamma-globulin and plasma IgG, and a decreased albumin/globulin (A/G) ratio.
- Plasma IL-6-like activity was significantly elevated in FIV-infected cats compared to controls.
- PBMC from FIV-infected cats spontaneously released higher levels of feline IL-6-like activity, primarily from monocytes/macrophages and partly from nonadherent cells.
Conclusions:
- Elevated feline IL-6-like activity is associated with FIV infection.
- Overproduction of IL-6 by immune cells in FIV-infected cats likely contributes to polyclonal B-cell activation.
Abstract:
The involvement of feline interleukin 6 (IL-6)-like activity in polyclonal B-cell activation in feline immunodeficiency virus (FIV) infection was investigated by using the proliferative response of hybridoma cell clone B3B1. Cats spontaneously infected with FIV had hyperimmunoglobulinemia, as shown by increases in the percentage of gamma-globulin and the plasma IgG concentration and decrease in the albumin/globulin (A/G) ratio. Because IL-6 plays an essential role in the differentiation of activated B cells into Ig-secreting cells, we examined the effect of FIV infection on the plasma IL-6 level. Plasma IL-6-like activity was found to be significantly higher in FIV-infected cats than in healthy controls. Peripheral blood mononuclear cells (PBMC) isolated from FIV-infected cats and cultured without any exogenous activators of IL-6 production released more feline IL-6-like activity than cells from healthy controls. This phenomenon was mainly due to the increase in the production of IL-6 by adherent cells such as monocytes/macrophages, but also partly by nonadherent cells. These results indicate that elevation of feline IL-6-like activity is associated with FIV infection and that overproduction of IL-6 may contribute to the polyclonal B-cell activation seen in FIV infection.