Abstract. Dams ETHM, Mascart-Lemone F, Schandené L, van der Meer JWM (University Hospital Nijmegen, Nijmegen, The Netherlands, and Hôpital Erasme, Brussels, Belgium). An unusual case of severe com bined immunodeficiency with hypereosinophilia (Case Report). J Intern Med 1997; 242: 2 6 7 -9 .Investigation of the cytokine profile in a 26-year-old m an, suffering from combined immunodeficiency with hypereosinophilia, revealed high levels of interleukin-4 and interleukin-5 and relatively low levels of interleukin-2 and interferon gam m a, consistent with a T-helper type 2 pattern, as has been reported in O m enn's syndrome. However, some distinct clinical and immunological features suggest that this case may represent a unique disease with specific patho genesis.