Final answer:
Integrins (LFA-1) play a role in firm adhesion during leukocyte extravasation, allowing leukocytes to cross the blood vessel wall and enter the tissues during diapedesis.
Step-by-step explanation:
During leukocyte extravasation, the role of integrins (LFA-1) is firm adhesion. Integrins are cell surface proteins that help leukocytes attach to the endothelial cells lining blood vessels. This firm adhesion is necessary for leukocytes to cross the blood vessel wall and enter the surrounding tissues during the process of diapedesis. Once the leukocytes are firmly adhered to the endothelium, they can proceed to squeeze through the adjacent cells and migrate into the tissues.