Re: Atopy and risk of non-Hodgkin lymphoma.

Melbye et al. ( 1 ) reported from their case – control study that participants with a history of hay fever or detectable serum antigen-specific immunoglobulin E (IgE) had a reduced risk of non-Hodgkin lymphoma (NHL). Two additional findings, however, led them to conclude that the inverse relationship between atopy and NHL, which was also observed in some other case – control studies, might be caused by NHL-induced suppression of the immunologic response to allergens. First, they reported that specific IgE levels were lower in case patients whose NHL was disseminated. Second, in a separate cohort of pregnant women, there was no association between low levels of specific IgE and subsequent risk of NHL, except among women who developed NHL less than 5 years after the blood was drawn. We would like to offer data in support of the first finding and an alternative interpretation of the second. First, we agree that NHL might have led to a reduced immunologic response. In a population-based case – control study of NHL, we too reported ( 2 ) an inverse relationship between atopic conditions, including hay fever and food allergies, and risk of NHL. We measured serum IgG, IgM, and IgA by nephelometry in 597 (85%) of the 704 case patients and 522 (75%) of the 694 control subjects after diagnosis (in case patients) or interview date (in control