The Relevance of Circulating Interleukin-5 (IL-5) in Lymphoproliferative Disorders

It is well substantiated that several cytokines have a regulatory action on the neoplastic process of different lymphoproliferative disorders (LPDs). The objective of this study was to clarify the role of interleukin-5 (IL-5) as a factor in disease phenotype and progression and as a mediator of eosinophilia in patients with LPDs. We have therefore measured the concentrations of IL-5 in sera of 49 untreated patients with different LPDs with mean (SD) age of 34.2 (21.2) years and M/F ratio of 29/20. Patients were subdivided according to the category of LPD into: Group 1 (NHL; n = 36), Group 2 (CLL; n = 5) and Group 3 (HD; n = 8). In addition, 14 matched controls were studied in parallel. The major differences among the three categories of LPDs were elicited in parameters reflecting the lymphocytic tumor burden; i.e. peripheral blood (F= 73.785; p =.000) and bone marrow (F = 55.662; p =.000) lymphocytic counts. Serum IL-5 level came next in statistical significance to lymphocytic parameters (F = 10.291; p =.000) with the highest levels being encountered in CLL patients. In NHL group, a concomitant rise of serum IL-5 levels accompanied the increasing grade of lymphoma (X(2) = 13.11; p =.004). Furthermore, IL-5 concentration was well correlated with different features known to be characteristic of LPDs; particularly and in a descending order: absolute eosinophilia (r =.599; p =.000), absolute lymphocytosis (r=.498; p =.000), bone marrow lymphocytosis (r =.436; p =.002) and bone marrow infiltration (r =.375; p =.008). The data are in favorof the fact that IL-5 is crucial in the generation of neoplastic phenotype and may also be responsible for some paraneoplastic features seen in LPDs.