Figure 1.

Monocytes from frail elderly subjects secrete reduced levels of proinflammatory cytokines and chemokines in response to toll-like receptors (TLR) ligation. TNF-α, tumour necrosis factor alpha; IL-6, interleukin-6; IL-8, interleukin-8; MCP-1, monocyte chemotactic protein-1; LPS, lipopolysaccharide; Zym, zymosan; Poly I:C, polyinosinic-polycytidylic acid; R848, resiquimod; Med, medium alone. Results are from 1 × 10⁶ monocytes from nine young and nine elderly individuals stimulated with various TLR ligands and analyses of culture supernatants 48 hours post-stimulation. The error bars represent standard error of means.