IL6 and bacterial urinary tract infection: TNF-α and IL-6 are more implicated than other cytokines in severe UTIs.17 Siransy et al revealed high levels of IL-6 in patients with SCD in crisis.34 IFN-γ, elevated as in this study, has been found to inhibit IL-5 production.35 Because our study groups consisted of asymptomatic UTI-infected HbSS subjects in steady state and uninfected HbSS, HbAS, and HbAA subjects, the levels of TNF-α, IL-5, and IL-6 may well be undetectable.