Submitted to: Journal of Clinical Investigation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/2003
Publication Date: 1/7/2004
Citation: Turcanu, V., Lack, G., Maleki, S.J. 2004. Characterisation of lymphocyte responses to peanut in normal children, peanut-allergic children and allergic children who acquired tolerance to peanuts. Journal of Clinical Investigation.
Interpretive Summary: To understand the abnormalities in the immune system of food allergic individuals, the T-cell (a type of immune cell) responses of: 1)peanut-allergic children, 2)children who outgrew peanut allergy, and 3)children who have always tolerated peanuts were compared. We found that food allergy is characterized by these immune cells. In other words, tolerating a food or having an allergic response to food is mostly dependent on the individuals immune system make up rather than the particular food.
Technical Abstract: Comparing lymphocyte responses to allergenic and non-allergenic foods could reveal the differences between pathogenic and normal immune responses to foods. Thus, defining the cytokine-producing phenotypes of peanut-specific lymphocytes from: 1)peanut-allergic children, 2)children who outgrew peanut allergy, and 3)children who have always tolerated peanuts may be useful to understand the mechanisms of food tolerance. However, investigating immune responses against foods is hindered by the fact that circulating food antigen-specific lymphocytes are very rare. In a novel approach, we used carboxyfluorescein succinimidyl ester to detect peanut-specific lymphocytes by flow cytometry. We confirmed that these cells are indeed peanut-specific by cloning. Peanut allergic donors show Th2-polarisation of cytokine production by peanut-specific cells (IFN low, TNF low, IL-4 high, IL-5 high, IL-13 high). Conversely, non-allergic and outgrown children show Th1-skewing to peanut antigens (IFN high, TNF high, IL-4 low, IL-5 low, IL-13low), similarly to non-allergenic food antigens ( -lactoglobulin, ovalbumin). This finding suggests that peanut antigens do not intrinsically induce Th2-skewing, but the type of response depends upon the donor's allergic status. In conclusion, food allergic status is characterised by a Th2 response while Th1-skewed responses underlie oral tolerance.