Use of Serum Concentrations of Interleukin-18 and Monocyte Chemoattractant Protein-1 as Prognostic Indicators in Primary Immune-Mediated Hemolytic Anemia in Dogs

Background The cytokine response in immune-mediated hemolytic anemia (IMHA) is poorly characterized and correlation with outcome is unknown. Hypothesis/Objectives To determine if cytokine activity is correlated with outcome in dogs with IMHA. Animals Twenty dogs with primary IMHA and 6 control dogs. Methods Prospective study on dogs with IMHA with blood sampling at admission. Serum activity of interleukin-2 (IL-2), IL-4, IL-6, IL-7, IL-8, IL-10, IL-15, IL-18, monocyte chemoattractant protein-1 (MCP-1), granulocyte-macrophage colony stimulating factor (GM-CSF), interferon-inducible protein-10, interferon-gamma, and keratinocyte chemoattractant (KC) was assessed. Results Thirty-day case fatality rate was 25% (5/20 dogs). Increased concentrations (median [range]) of IL-2 (45.5 ng/L [0;830] versus 0 ng/L [0;46.8]), IL-10 (8.2 ng/L [0;60.6] versus 0 ng/L [0;88.2]), KC (1.7 mu g/L [0.3;4.7] versus 0.5 mu g/L [0.2;1.1]), and MCP-1 (162 ng/L [97.6;438] versus 124 ng/L [90.2;168]) were observed in dogs with IMHA compared with controls. The cytokine profile was indicative of a mixture of pro- and anti-inflammatory cytokines of various cellular origins. Cytokines/chemokines strongly associated with macrophage/monocyte activation and recruitment were significantly increased in nonsurvivors compared with survivors; IL-15 (179 ng/L [48.0;570] versus 21.3 ng/L [0;193]), IL-18 (199 ng/L [58.7;915] versus 37.4 ng/L [0;128]), GM-CSF (134 ng/L [70.0;863] versus 57.6 ng/L [0;164]), and MCP-1 (219 ng/L [135;438] versus 159 ng/L [97.6;274]), respectively. Logistic regression suggested increased IL-18 and MCP-1 concentrations were independently associated with mortality in this population (P <.05, Wald's type 3). Conclusions and Clinical Importance A mixed cytokine response is present in dogs with IMHA and mediators of macrophage activation and recruitment might serve as prognostic indicators.