IL15 and B-cell chronic lymphocytic leukemia: The stimulation of CLL cells via the BcR can be modulated by additional signals that are capable of determining the outcome; for example, sIgM cross-linking is often followed by cell apoptosis or anergy in vitro, although the addition of IL4, IL2, IL10 or IL15 may induce some cell proliferation and prolong cell survival [114,192,193].