Spontaneous expression of the interleukin 2 receptor gene and presence of functional interleukin 2 receptors on T lymphocytes in the blood of individuals with active pulmonary sarcoidosis

Increased numbers of T lymphocytes with gamma delta-positive antigen receptors in a subgroup of individuals with pulmonary sarcoidosis

Individuals with sarcoidosis were evaluated for preferential usage of T cells with the gamma delta-positive (+) type of T cell antigen receptor. Compared with normal subjects (n = 19), the group with sarcoidosis had increased numbers of CD3+ alpha beta-negative (-) T cells in the blood (normal, 58 +/- 12 cells/microliters; sarcoid, 192 +/- 45 cells/microliters, P less than 0.05) and in the epithelial lining fluid of the lung (normal, 78 14 cells/microliters; sarcoid, 240 +/- 60 cells/microliters, P less than 0.04) and a concomitant elevated number of blood and lung CD3+ gamma delta+ T cells, owing to a striking increase in the number of CD3+ gamma delta+ T cells in a subgroup (7 of 20) of sarcoid individuals. The elevated numbers of sarcoid blood gamma delta+ T lymphocytes were mostly Ti gamma A+ and delta TCS1-, a pattern also seen in normal individuals, consistent with the majority of gamma delta+ T cells expressing one gamma-chain variable region, V gamma 9. The observation of an increase in the total gamma delta+ T cell numbers in a sarcoid subgroup suggests that various specific stimuli may trigger the expansion of different T cell subpopulations within different groups of individuals with sarcoidosis.

Suppression of interleukin 2-dependent human T cell growth in vitro by prostaglandin E (PGE) and their precursor fatty acids. Evidence for a PGE-independent mechanism of inhibition by the fatty acids

PGE represent oxygenation products of polyunsaturated essential fatty acids and are important regulators of cell-mediated immune responses. Because oils enriched in such fatty acids reduce inflammation and tissue injury in vivo, we examined the effects of these PGE precursors on IL-2-driven growth of human T lymphocytes. Dihomogamma linoleic acid (DGLA), AA, and their metabolites (PGE1 and PGE2, respectively) strongly inhibited short- and long-term growth of IL-2-dependent T cell cultures; EPA was much less inhibitory and its product, PGE3, failed to suppress IL-2 responses. Short-term pretreatment of the cells with DGLA or AA and removal of the fatty acids before the proliferation assay resulted in a smaller reduction in [3H]TdR incorporation. PGE and fatty acids did not alter the number of high affinity IL-2 binding sites on the T cell cultures but reduced the percentage of cells expressing CD25 and HLA class II molecules. No PGE was detected in supernatants from the fatty acid-treated cultures. Moreover, indomethacin, a cyclooxygenase inhibitor, did not reverse the antiproliferative effects of the fatty acids. Together, these findings indicate that fatty acids can inhibit IL-2-driven T cell growth via a PGE-independent mechanism and might be relevant to inflammatory diseases associated with persistent T cell activation.

Bias toward use of a specific T cell receptor beta-chain variable region in a subgroup of individuals with sarcoidosis

To evaluate the concept that biases in the usage of T cell antigen receptor beta variable (V) regions may be manifested in T lymphocytes that accumulate in nonmalignant, T cell-mediated human disorders, a V beta 8-specific antibody (anti-Ti3A, 5REX9H5) was used to evaluate lung and blood T cells in pulmonary sarcoidosis, a chronic granulomatous disorder of unknown etiology. Whereas normal patients had less than 5% Ti3A+ lung (n = 7) and/or blood (n = 9) lymphocytes, strikingly, a subgroup (8 of 21) with active pulmonary sarcoidosis had greater than 7% Ti3A+ lung and/or blood T cells and a higher proportion of Ti3A+ lymphocytes in the lung compared with blood. Dual-color flow cytometry demonstrated compartmentalization of Ti3A+ CD4+ lymphocytes to lung and Ti3A+ CD8+ lymphocytes to blood. Analysis with a 32P-labeled V beta 8 probe revealed that sarcoid lung T lymphocytes contained higher amounts of V beta 8+ mRNA than autologous blood T cells. However, Southern analysis of sarcoid lung and blood T cell DNA demonstrated no evidence of clonal rearrangements of V beta 8 genes. These observations demonstrate a clear bias toward the use of at least one V beta region in sarcoidosis, and suggests T cells accumulate secondary to external selective pressure, rather than in a random polyclonal fashion or by clonal expansion of one or few T cell clones.