Ascaris Lumbricoides Infections Evoke Polarized Cytokine Response
This is a very, very important article for two reasons. First, it brings to light to high numbers of parasites present in humans (some labs suggest numbers as high as 20% of their samples have parasites). And, it demonstrates an effect of these parasites on Th1/Th2 ratios, a very important balance between fighting off infections and autoimmunity. Some researchers believe that the parasites are able to cause our immune system to shift to Th2, which is not as effective at fighting off parasites.
J Infectious Diseases 2000;182:1207-1213 Ascaris lumbricoides infections in humans are associated with a highly polarized type 2 cytokine response. Dr. Philip J. Cooper of the National Institutes of Health in Bethesda, Maryland, and an international team of researchers explain that helminthic infections affect a large proportion of the population. As “experimental animal and human studies have demonstrated that concurrent helminthiases may modulate the immune responses to bystander antigens (e.g., vaccines),” the authors note the importance of knowing the “phenotype of the cellular response to A. lumbricoides.” They found that members of the infected group “both produce and express greater levels of the type 2 cytokines IL-4 and IL-5 than do uninfected endemic control subjects.” As the production of IL-10 and interferon-gamma was similar in the two groups, the “ratios of Th2 to Th1 cytokine frequencies were significantly elevated in the infected group.”