IL4 and infection: infantum.<h4>Methods</h4>Primary macrophages were matured from peripheral blood mononuclear cells of a healthy domestic cat, and cells were collected at different time points post-infection (i.e., 4, 24, and 72 h) for microscopic evaluation and quantitative real-time PCR analysis of cytokine expression [interleukin (IL)-2, IL-4, IL-6, IL-10, interferon (IFN)-γ, and tumor necrosis factor (TNF)-α].<h4>Results</h4>Infection rates ranged from 35.6% to 48.2%, with 2.1-2.4 intracellular parasites per infected cell.