IL2RB and nutritional deficiency disease: donovani IgG titres found here between the Indian and Sudanese VL patients in this study may result from a combination of environmental and genetic factors, in which malnutrition with Zn2+ deficiency, differences in IL-2 responses due to polymorphisms in IL-2 and its receptor (IL-2Rα and IL-2Rβ) genes and possibly HLA-DRB1 and HLA-DQA1 genes are to date the most likely candidates.