What occurs during diapedesis?

Diapedesis refers to the process by which white blood cells, primarily leukocytes, move out of the bloodstream and into tissues. This movement is crucial for the immune response, particularly during inflammation or infection. During diapedesis, leukocytes squeeze through the walls of capillaries, which often involves changes in cell shape and the disengagement of the cell adhesion molecules that normally keep them bound to the endothelium of blood vessels. By migrating out of the blood and into affected tissues, these cells can target and combat infections or address other immune challenges.

The other processes listed involve different mechanisms in the immune response. For instance, the production of leukocytes occurs in the bone marrow, which is not related to their movement during diapedesis. Antibody formation is a separate aspect of the immune response that involves B cells. Similarly, macrophage activation and pathogen engulfment, while related to immune responses, describe different actions that do not specifically pertain to the movement of leukocytes through capillary walls. Therefore, diapedesis specifically captures the process of white blood cells transitioning from the bloodstream into tissues.