Interaction of staphylococcal toxic shock syndrome toxin-1 and enterotoxin A on T cell proliferation and TNFα secretion in human blood mononuclear cells

Abstract

BACKGROUND: The majority of menstrual toxic shock syndrome (MTSS) cases are caused by a single clone of Staphylococcus aureus that produces both toxic shock syndrome toxin-1 (TSST-1) and staphylococcal enterotoxin A (SEA). OBJECTIVE: To determine whether the two superantigens interact to cause an enhancement of biological activity in human peripheral blood mononuclear cells (PBMCs). DESIGN: PBMCs from nine healthy donors were stimulated with TSST- 1 or SEA, either alone or in combination at their minimum effective concentrations. SETTING: In vitro study. INTERVENTIONS: Human PBMCs were stimulated in vitro with TSST-1 (1 pg/mL), SEA (0.1 pg/mL) or combination for 20 to 72 h. Mitogenic response was determined by [3H]-thymidine incorporation. PBMC culture supernatants were assayed for the presence of tumour necrosis factor-alpha (TNFα), interleukin (IL)-1β and IL-6 by ELISA. MAIN RESULTS: The combination of TSST-1 and SEA induced significantly greater mitogenesis in human PBMCs compared with either toxin alone (P <0.05). In contrast, no enhancement in the levels IL-1 or IL-6 was observed. CONCLUSIONS: These data suggest that the co-production of TSST- 1 and SEA by S aureus may provide some biological advantage to the organism through an enhanced effect of these superantigens on T cell activation and TNF secretion.