Table 3 |.

Controls to test for potential false-negative or false-positive results

Description/control	IEC	CFC
Primary purpose	Rule out false-negative results	Rule out false-positive results
Content	Positive-control supernatant from Step 39 spiked with NANPs	Complete cell culture medium and NANPs. See Step 35 for the details of preparation
	CFC supernatant from Step 39 spiked with cytokine standards from ELISA kit

Inhibition enhancement control (IEC) and cell-free control (CFC) help reveal the ability of NANPs present in the culture supernatants to alter cytokine detection and cause false-positive or false-negative results. More details are in Step 35.