In recent years our knowledge in terms of the network of interactions between immunocompetent cells that set the stage for the pathogenesis of sarcoidosis has continuously improved. Remarkable advances have been made in understanding general immunological and molecular aspects of the mechanisms leading to granuloma formation. In this manuscript we will review the current concepts on cellular interactions which define regulatory networks ultimately contributing to the granuloma formation at sites of disease activity in sarcoidosis. The biological effects of Th1 and Th2 cytokines in sarcoid lung will be taken into account and the importance of the local production of those chemokines and cytokines whose release has been recently demonstrated within the lung of patients with sarcoidosis will be emphasized.