Final answer:
The answer is true. Immune ignorance can occur when the concentration of an antigen is very low and the immune system does not recognize it, potentially allowing pathogens to escape detection.
Step-by-step explanation:
Is a low concentration of antigen considered one reason for immune ignorance? The answer to this question is true. Immune ignorance refers to a situation where the immune system does not recognize or respond to an antigen. This can occur when the concentration of an antigen is very low, making it less likely for immune cells to encounter and respond to it. A high threshold for activation of the immune response ensures that the body does not overreact to minor exposures, which is a protective measure to prevent unnecessary or harmful inflammation. However, if an antigen remains below this threshold, it may not elicit a sufficient immune response, leading to immune ignorance and potentially allowing a pathogen to avoid detection and elimination by the immune system.