ABSTRACT
Since the observation of a common impairment of cutaneous delayed
hypersensitivity in sarcoidosis, T-cells recovered from both peripheral
blood and tissues involved by the disease have been extensively investigated.
The identification of leukocyte surface molecules that divide lymphocytes into functionally distinct subsets and the definition and cloning of several
molecules regulating inflammatory and immune responses are among the
remarkable advances that have had a relevant impact on the understanding
of the functional role of lymphocytes in sarcoidosis. The definition of the
molecular basis of antigen recognition and the characterization of factors
regulating lymphocyte homing also helped to understand the processes by
which lymphocytes seek out and localize inflamed tissues during sarcoid
inflammatory process. In this chapter, we will review the current concepts on the relevant
phenotypic and functional abnormalities of T-lymphocytes in the lower
respiratory tract of patients with sarcoidosis. Furthermore, we will talk
about the recent findings on the ability of immunomodulatory molecules,
such as proinflammatory cytokines, chemokines, and other cytokines, to
regulate T-cell function in immune mechanisms leading to granuloma
formation and maintenance.
