No abstract

The presence of a prominent tissue eosinophilia represents a typical histopathologic hallmark of Hodgkin's disease (HD). To evaluate the putative role of eosinophils on tumor cell regulation in HD, we have analyzed these cells for the functional expression of CD30 ligand (CD30L), a surface molecule able to transduce CD30-mediated proliferation signals on Hodgkin's (H) and Reed-Sternberg (RS) cells. The results demonstrate that circulating and tissue eosinophils from normal donors and patients with HD or hypereosinophilic syndrome (HES), display CD30L mRNA and express CD30L protein, as shown by immunostaining with a specific monoclonal antibody (M80) and with a biotinylated soluble CD30-Fc fusion protein. The surface density of CD30L on eosinophils from HD and HES patients was remarkably higher compared with healthy donors, probably reflecting a cytokine-mediated upregulation in these pathologic conditions. Accordingly, we provide evidence that cytokines regulating eosinophils proliferation and activation, ie, interleukin-5 (IL-5), IL-3, and granulocyte-macrophage colony-stimulating factor (GM-CSF), are able to enhance the cellular density of CD30L on purified eosinophils from normal subjects. Finally, we show that native CD30L on human eosinophils is a functionally active surface structure able to transduce proliferative signals on CD30+ target cells, including cultured H-RS cells. Our data suggest that eosinophils may not merely represent innocent bystanders, but rather act as important elements in the pathology of HD by contributing to the deregulated network of CD30/CD30L-mediated interactive signals between H-RS cells and surrounding reactive cells.

recently, several bcl-2-related genes were cloned

Hodgkin's disease (HD) is a peculiar type of human malignant lymphoma characterized by a very low frequency of tumor cells, the so called Hodgkin and Reed-Sternberg (H-RS) cells, embedded in a hyperplastic background of non-neoplastic (reactive) cells recruited and activated by H-RS cells-derived cytokines. H-RS cells can be functionally regarded as antigen-presenting cells (APC) able to elicit an intense, but anergic and ineffective, T-cell mediated immune response along with a hyperplastic inflammatory reaction which involves several cell types including T- and B-cells, neutrophils, eosinophils, plasma cells, fibroblasts and stromal cells. In tissues involved by HD, malignant H-RS cells and their reactive neighboring cells are able to cross-talk via a complex network of cytokine- and cell contact-dependent interactions. As a result of such interactions, mediated by specific surface receptors and adhesion molecules on both tumor and non-neoplastic cells, H-RS cells may receive several proliferative and anti-apoptotic signals favoring the cellular expansion and tumor cell survival in HD. The ineffective T-cell immune response elicited by the abnormal APC function of H-RS cells may further contribute to the biologic and clinical progression of HD. Innovative therapeutic strategies aimed at blocking the pathways of dysregulated cellular cross-talk among H-RS cells and bystander reactive cell populations might be beneficial in the treatment of HD patients.

Our data suggest that eosinophils may act as important elements in the pathology of HD by providing cellular ligands for TNF-superfamily receptors (CD40, CD30, CD95/Fas) able to transduce proliferation and antiapoptotic signals at the surface of H-RS cells. The presence on eosinophils of receptors for TNF ligands expressed by activated T cells (i.e., OX40L, FasL, CD40L, 4-1BBL), also suggest that eosinophils may contribute to the deregulated network of interactive signals between H-RS cells, T cells, and other surrounding reactive cells.