In vitro response of lymphocytes from bronchoalveolar lavage fluid and peripheral blood to mitogen stimulation during natural maedi-visna virus infection.
To investigate the effects of maedi-visna virus (MVV) infection on cell-mediated immunity, the in vitro response of bronchoalveolar lavage fluid (BALF) and peripheral blood (BP) lymphocytes (PBL) to exogenous mitogen was analysed. BALF and PBL from control (n = 9) and MVV-infected (n = 7) animals were cultured fro 3 days in the presence and absence of concanavalin A (Con A). Lymphocyte expression of the interleukin-2 receptor (IL-2R) antigen, a parameter of lymphocyte activation, was quantified by dual-colour flow cytometry using the bovine anti-IL-2R monoclonal antibody IL-A111. IL-2R expression by lymphocytes in BALF and PB from control and MVV-infected animals, with and without Con A stimulation, were compared. In the absence of Con A stimulation, the proportion of cultured BALF CD8+ and gamma delta T cells expressing IL-2R was significantly (P < 0.05) lower for MVV-infected animals than for controls. After Con A stimulation the proportion of BALF CD4+ lymphocytes from MVV-infected animals that expressed IL-2R remained significantly (P < 0.05) lower than for controls. Comparisons within group showed that, after Con A stimulation, the proportion of all the T cell subsets in the control group expressing IL-2R, namely CD4+ (P < 0.001), CD8+ (P < 0.001) and gamma delta T cells (P < 0.05), was significantly increased. In the MVV-infected group, this increase was significant (P < 0.05) for CD4+ and CD8+ T cells, but not for gamma delta T cells. In vitro mitogen stimulation of PB T lymphocytes from both control and MVV-infected animals induced a significant elevation in the proportion of all T cell subsets expressing IL-2R when compared to cultured unstimulated control cells. However, there was considerable heterogeneity in the response to Con A of PB T cells from both groups of animals. The expression of IL-2R followed a different pattern to that of BALF lymphocytes, the proportion of unstimulated gamma delta / IL-2R+ T cells from MVV-infected animals being significantly (P < 0.05) higher than that of controls, and the proportion of cultured unstimulated CD8+ / IL-2R+ T cells from MVV-infected animals being significantly (P < 0.05) lower than that from controls. From these studies it can be concluded that the BALF T lymphocyte immune dysfunction observed during natural MVV infection, characterized by impaired IL-2R expression, is maintained under in vitro conditions.
Begara
I
I
Department of Veterinary Clinical Studies, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian, UK.
Luján
L
L
Collie
D S
DS
Miller
H R
HR
Watt
N J
NJ
D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002417:Cattle; D003208:Concanavalin A / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000276:immunology*; D016676:Macrophages, Alveolar / Q000276:immunology; D011021:Pneumonia, Progressive Interstitial, of Sheep / Q000276:immunology*; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000378:metabolism; D015375:Receptors, Interleukin-2 / Q000378:metabolism; D012756:Sheep; D016176:T-Lymphocyte Subsets / Q000276:immunology
D016692:Receptors, Antigen, T-Cell, gamma-delta; D015375:Receptors, Interleukin-2; D003208:Concanavalin A