Researchers from Richmond, Virginia, USA, investigated whether ethnicity and cytokine production can be used to gauge the response of patients with hepatitis C to interferon-alpha therapy.
Interferon (IFN) is the primary treatment for hepatitis C virus (HCV). However, the long-term success rate is low, particularly for African Americans relative to Caucasians, and may be due to differential immune abilities.
The study compared cytokine production from phytohemagglutinin-stimulated peripheral blood from 25 healthy and 40 HCV-infected African Americans and Caucasians.
HCV patients were designated as IFN responders or nonresponders, based on outcome after therapy.
The researchers found that ethnicity and genotype were associated with IFN response.
IFN responders were 100% Caucasian, whereas nonresponders were 67% Caucasian and 33% African American.
Cytokine production from healthy individuals showed ethnic variation in cytokine levels. Healthy African Americans were found to produce greater amounts of IL-2 and TNF-alpha, and less IL-10 than healthy Caucasians. In contrast, IFN-gamma and TGF-beta levels were equivalent.
Pretherapy cytokine production among HCV patients showed a similar pattern of ethnic variation.
| No African Americans responded to IFN therapy.
| Journal of Medical Virology |
Among nonresponders, African Americans produced more IL-2 and TNF-alpha than Caucasians. On the contrary, Caucasian responders produced subnormal levels of IL-10 and TGF-beta.
Since all African Americans failed IFN therapy, cytokine production could not be compared with therapeutic outcome.
However, comparison of cytokine production among Caucasians showed that responders produced less IL-10 and more TGF-beta than nonresponders. It also predicted Caucasian nonresponders with 83% sensitivity and 96% specificity.
Pam Kimball, of the Department of Surgery at the Medical College of Virginia at the Virginia Commonwealth University, said on behalf of the group, "It appears that ethnicity may contribute to variable immune responses and therapeutic outcome.
"The cytokine profile among African Americans suggests a more robust immune response, which may complicate therapy with IFN.
"In contrast, the subnormal cytokine production among Caucasian responders may be more permissive to IFN therapy."
"Pretherapy cytokine production may allow prediction of drug resistance among Caucasians," it was concluded.