Final answer:
ILCs and NK cells help control the pathogen until the development of adaptive immunity. Macrophages are the cells that can phagocytize pathogens and promote inflammation. Adaptive immunity, developing later, leads to complete pathogen clearance.
Step-by-step explanation:
Innate immune cells like ILCs (innate lymphoid cells) and NK (natural killer) cells play a crucial role in bridging the gap between the immediate innate immune response and the more specialized adaptive immune response. These cells help keep the pathogen in check by various means until the development of adaptive immunity occurs. Specifically, the ILCs and NK cells maintain control over pathogen spread in the initial days of infection until the adaptive immune system is fully activated and capable of clearing the pathogen.
Regarding the type of immune system cell that can both phagocytize pathogens and produce chemicals that promote inflammation, macrophages are the correct answer. Macrophages are versatile cells that act as antigen-presenting cells (APCs) and are critical in both initiating an inflammatory response and in presenting antigens to T cells, which are pivotal in the development of the adaptive immune response.
It is important to note that while NK cells and macrophages are part of the innate immune system and can respond quickly to infections, the ultimate clearance of pathogens is typically accomplished by the adaptive immune system's B cells and T cells, which include memory cells that provide long-lasting protection.