Chemoattractant(s) in Culture Supernatants of HTLV-I-Infected T-Cell Lines

Abstract

Supernatants obtained from four HTLV-I transformed cell lines (MT2, MT4, C91/PL, and 81-66/45) induced in vitro migration of monocytes, polymorphonuclear leukocytes (PMN), and lymphocytes. The MT2, C91/PL, and 81-66/45 cell lines expressed both lymphotoxin (LT) and tumor necrosis factor (TNF-α) mRNA transcripts, and had TNF biological activity. In contrast, the MT4 cells did not express LT mRNA, had low levels of TNF-α transcript, and no TNF activity in the supernatant. Anti-TNF-α MAb, which blocks the chemotactic activity of recombinant TNF-α, had no inhibitory effect on the induction of migration by the MT2 and MT4 supernatants. Hence, no correlation was evident between TNF and chemotactic activity in supernatants of different HTLV-I-infected cell lines. Upon fractionation on Sephadex G50, the monocyte chemoattractant(s) eluted with two peaks in the 8-12 kD region, a size compatible with the chemotactic cytokines IL-8 and monocyte chemotactic protein (MCP). However, anti-IL-8 and anti-MCP antibodies did not have any effect, and Northern blot analysis showed that HTLV-I-transformed cell lines did not express mRNA transcripts of either IL-8 and MCP. These results demonstrate that HTLV-I transformed T-cell lines produce chemoattractant(s) active on PMN and monocytes, distinct from LT, TNF-α, IL-8, and MCP. Production of chemoattractants may play a role in the pathogenesis of diseases associated with HTLV-I infection.