Pekka Kotovuori

Leukocyte integrins and inflammation

Abstract. Leukocyte adhesion is of pivotal functional importance. Without adequate adhesion, T lymphocytes and natural killer cells are not cytotoxic, B cells cannot develop into antibody secreting plasma cells, leukocytes do not home into inflamed tissues and myeloid cells are not able to phagocytize or exhibit chemotactic responses. During evolution several leukocyte adhesion molecules have developed belonging to a few molecular families. Among these, the leukocyte-specific integrins (β2 integrins, CD11/CD18 molecules) are among the most important. Much progress has taken place during the past few years, and at present we have a considerable knowledge of their structure and function. Inflammation is critically dependent on integrin activity, and its regulation forms the topic of this short review.

The pivotal role of the Leu-CAM and ICAM molecules in human leukocyte adhesion

Cellular adhesion is of fundamental importance in leukocyte physiology. It is a complex, strictly regulated process, which involves the participation of several cell surface glycoproteins. Among the most important are the Leu-CAMs or the CD11/CD18 integrin receptors, and their adhesion ligands ICAM-1 (CD54) and ICAM-2. In this review we summarize some recent work on various aspects of these molecules.

Leukocyte Adhesion’an Integrated Molecular Process at the Leukocyte Plasma Membrane

Leukocyte adhesion is of pivotal functional importance, because most leukocyte functions depend on cell–cell contact. It must be strictly controlled, both at the level of specificity and strength of interaction, and therefore several molecular systems are involved. The most important leukocyte adhesion molecules are the selectins, the leukocyte-specific β2-integrins and the intercellular adhesion molecules. The selectins induce an initial weak contact between cells, whereas firm adhesion is achieved through integrin–intercellular adhesion molecular binding. Although studies during the past twenty years have revealed several important features of leukocyte adhesion much is still poorly understood, and further work dealing with several aspects of adhesion is urgently needed. In this short essay, we review some recent developments in the field.

Leukocyte adhesion - a fundamental process in leukocyte physiology

Leukocyte adhesion is of pivotal functional importance. The adhesion involves several different adhesion molecules, the most important of which are the leukocyte beta 2-integrins (CD11/CD18), the intercellular adhesion molecules, and the selectins. We and others have extensively studied the specificity and binding sites in the integrins and the intercellular adhesion molecules for their receptors and ligands. The integrins have to become activated to exert their functions but the possible mechanisms of activation remain poorly understood. Importantly, a few novel intercellular adhesion molecules have been recently described, which seem to function only in specific tissues. Furthermore, it is becoming increasingly apparent that changes in integrins and intercellular adhesion molecules are associated with a number of acute and chronic diseases.