When cell-free extracts were made from peripheral blood mononuclear cells (PBMC) obtained from cutaneous T-cell lymphomas, there was a 10-fold increase in the 2′,5′-oligoadenylate synthetase activity compared with that of normal PBMC. The increased synthetase activity was based on the increased synthesis of 2′,5′-adenylates of molecular size of trimer or greater (dimer adenylate was not included because dimer adenylate does not inhibit protein synthesis). The 10-fold increase in 2′,5′-adenylates was determined by (i) the conversion of ATP to 2′,5′-oligoadenylate by cell-free extracts of PBMC and measurement of the 2′,5′-adenylates following displacement from a DEAE-cellulose column by 350 mM KCl, (ii) measurement of 2′,5′-adenylates synthesized following gradient separation and displacement from a DEAE-cellulose column, and (iii) synthesis of 2′,5′-adenylates with time of incubation. Whereas only two 2′,5′-adenylates that inhibit protein synthesis (i.e., trimer and tetramer) are synthesized by normal PBMC, trimer, tetramer, pentamer, and hexamer are synthesized by PBMC from cutaneous T-cell lymphomas. The significance of the synthesis of higher molecular weight 2′,5′-adenylates is that in vitro protein synthesis is inhibited 30% by a 2500-fold dilution of the 2′,5′-oligoadenylates synthesized by 2′,5′-oligoadenylate synthetase in PBMC cell-free extracts from cutaneous T-cell lymphoma, whereas a 2500-fold dilution of the 2′,5′-oligoadenylates from normal PBMC is not inhibitory. No appreciable difference in 2′,5′-oligoadenylate synthetase activity was found between T-cells and non-T-cells from cutaneous T-cell lymphomas. The response of PBMC after 24-h exposure to interferon, as measured by increased 2′,5′-oligoadenylate synthetase activity, showed no difference between cutaneous T-cell lymphomas and normals. These results demonstrate an increased activity of 2′,5′-oligoadenylate synthetase in PBMC from cutaneous T-cell lymphomas. The increased synthetase activity, in particular the increased synthesis of 2′,5′-adenylate tetramer, pentamer, and hexamer, suggests that a change in the biochemistry of cellular processes has occurred. This change might be attributable to a virus. Measuring increased synthetase activity by examination of the 2′,5′-adenylate profile may be a reliable method to substantiate viral etiology because there is a significant increase in 2′,5′-adenylate synthetase activity in all PBMC samples assayed, whereas virus particles cannot be isolated from most PBMC.
|Original language||English (US)|
|Number of pages||6|
|State||Published - 1983|
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