How does the immune system prevent attacking its own body tissues?

The immune system prevents attacking its own body tissues primarily through the process known as tolerance, which is effectively achieved by the suppression of immune cells that are specific to the body's own antigens. During the development of T cells and B cells in the thymus and bone marrow, respectively, cells that react strongly to self-antigens are typically eliminated through a process called negative selection. This helps ensure that the resulting immune repertoire is tolerant to self and reduces the risk of autoimmunity.

In addition to this negative selection, regulatory T cells play a crucial role in maintaining tolerance by actively suppressing any potentially autoreactive immune responses that could lead to tissue damage. This allows the immune system to function effectively against pathogens while avoiding harmful reactions against the body's own cells.

The other options, while related to aspects of immune function, do not specifically address the mechanism of self-tolerance in the same way. Producing antibodies can lead to a response against foreign antigens but does not inherently prevent autoimmunity. Increasing cytokine production typically enhances immune responses but is not a mechanism of self-tolerance. Activating memory cells relates to the adaptive response upon re-exposure to specific pathogens and does not specifically involve preventing self-attack.