The hypereosinophilic syndrome associated with CD4+CD3- helper type 2 (Th2) lymphocytes.

We describe herein the clinical and laboratory manifestations of a unique group of patients (pts) presenting with hypereosinophilic syndrome (HES) who were treated in our medical centers for 4-13 years. Skin biopsies, flow cytometry of peripheral blood mononuclear cells (PBMC), assays for cytokines and immunoglobulin (Ig) production in vitro, and Southern blots of T-cell receptor (TCR) genes were performed. All four pts had a persistent hypereosinophilia (> 1.9 x 10(9)/L) and chronic skin rash. Three of four had elevated IgE, thrombotic manifestations and lung involvement (asthma and/or infiltrates), and one had deforming sero-negative arthritis of the hands. 66-95% of their peripheral T-cells expressed CD4 but not CD3 or TCR molecules on the cell surface membrane. Activated CD4+CD3- cells secreted interleukin (IL)-4 and/or 5, and were required for maximal IgE secretion by autologous B-cells. Two pts had evidence of rearrangement of TCR genes of the CD4+CD3- cells, one of whom died of anaplastic lymphoma. In conclusion, HES with CD4+CD3- lymphocytosis may be associated with high serum IgE, dermatological, pulmonary, thrombotic and rheumatic manifestations which may be due to Th2 effects of CD4+CD3- cells migrating to end organs. Fatal systemic lymphoid malignancy may also develop in some pts with monoclonal expansion of the CD4+CD3- T-cells.