What is Host Response?
Host response, also referred to as host gene response or host immune response, is the way a body—human or animal—reacts to internal and external stressors such as infections, trauma, and illness. The way in which the host has been affected by bacteria or other invasive infection triggers immune responses to combat that stressor. Each host’s response is specific and unique, determined by the host’s genetic composition.
Today, scientists can use these unique expressions to understand whether an invader is bacterial, viral, or parasitic, enabling faster, more accurate diagnoses.
How Do Host Response Diagnostics Work?
Host response-based diagnostics are a new tool used to identify and monitor infections and other diseases. Unlike traditional diagnostic methods that are designed to detect the presence of a single, specific pathogen, host response diagnostics measure the immune response of the host to the pathogen.
This difference is critical: traditional diagnostics take a hunt-and-peck approach to identify an illness; host response diagnostics operate through a process of elimination. By identifying a host’s response to a set of stressors, entire categories of potential pathogens can quickly be eliminated from consideration, enabling faster diagnoses.
The host response to an infection involves a complex interplay between the innate and adaptive immune systems. When a pathogen enters the body, the innate immune system detects it and mounts a rapid, non-specific response. This response includes the activation of immune cells, such as macrophages and neutrophils, and the release of cytokines and chemokines, which are signaling molecules that help coordinate the immune response.
The adaptive immune system, which includes B cells and T cells, takes longer to respond to an infection but is more specific. B cells produce antibodies that can bind to and neutralize the pathogen, while T cells can directly kill infected cells.
Host response diagnostics measure various components of this immune response to detect the presence of an infection or monitor disease progression. For example, some host response tests measure the levels of cytokines or other immune signaling molecules in blood samples, while others may measure the expression of specific genes associated with the immune response.
By measuring the host response to an infection, these tests can help differentiate between different types of infections and monitor the effectiveness of treatments. Host response diagnostics may also be used to identify individuals who are at risk of developing severe or chronic infections, which can inform treatment decisions and improve patient outcomes.
