Heat stress (HS) is a major environmental stressor to chickens because chickens lack sufficient physical ability to mitigate heat. One of the potential results of heat stress is the “leaky gut syndrome”, which allows gut bacteria to escape into the host and release toxins including lipopolysaccharide (LPS). To model the chicken immune response to bacteria toxins under heat stress, a chicken macrophage-like cell line, HD11, was subjected to HS, LPS, or HS + LPS treatments. Expression of a gene panel of heat shock proteins, stress-related molecules, signaling molecules, and immune response molecules were measured and analyzed at 4 time points across the 3 conditions. As expected, heat shock proteins and immune response molecules increased in expression during HS and LPS challenge, respectively. Treatment of HS + LPS increased the expression of these responsive genes even more than either treatment alone. This suggests that heat stress proteins not only mitigate heat stress, but also trigger a higher level of immune response in chickens.