In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: In addition , interleukin - 6 ( IL - 6 ) as an early marker of inflammation was assessed in a subgroup of 10 patients pretreated with saline .
### Output Text:
In addition , interleukin - 6 ( IL - 6 ) as an early marker of inflammation was assessed in a subgroup of 10 patients pretreated with saline . 