Pharmaceutically pure HA binds to macrophages indirectly by CD44, but does not cause the production of TNF-α, IL-12, CD40, CD86, IL-1β. Binding of HA with macrophages does not lead to the production of TNF-α, IL-12, CD40, CD86, IL-1β. Pharmaceutically pure HA does not cause pneumonia. This evidence concerns the gene IL1B and susceptibility to pneumonia measurement.