Development of chronic lymphocytic leukaemia in a case of Sjögren's syndrome with systemic lupus erythematosus

Phosphoproteomics Reveals the Role of Constitutive KAP1 Phosphorylation by B-Cell Receptor Signaling in Chronic Lymphocytic Leukemia

Application of B-cell receptor (BCR) pathway inhibitor ibrutinib for chronic lymphocytic leukemia (CLL) is a major breakthrough, yet the downstream effects following inhibition of BCR signaling and during relapse await further clarification. By comparative phosphoproteomic profiling of B cells from patients with CLL and healthy donors, as well as CLL B cells collected at multiple time points during the course of ibrutinib treatment, we provided the landscape of dysregulated phosphoproteome in CLL and its dynamic alterations associated with ibrutinib treatment. Particularly, differential phosphorylation events associated with several signaling pathways, including BCR pathway, were enriched in patient CLL cells. A constitutively elevated phosphorylation level of KAP1 at serine 473 (S473) was found in the majority of CLL samples prior to treatment. Further verification showed that BCR activation promoted KAP1 S473 phosphorylation, whereas ibrutinib treatment abolished it. Depletion of KAP1 in primary CLL cells decelerated cell cycle progression and ectopic expression of a KAP1 S473 phospho-mimicking mutant accelerated G2/M cell cycle transition of CLL cells. Moreover, temporal phosphoproteomic profiles using a series of CLL cells isolated from one patient during the ibrutinib treatment revealed the dynamic changes of several molecules associated with BCR signaling in the ibrutinib responsive and recurrent stages. Implications: This phosphoproteomic analysis and functional validation illuminated the phosphorylation of KAP1 at S473 as an important downstream BCR signaling event and a potential indicator for the success of ibrutinib treatment in CLL.

Chronic lymphocytic leukemia and autoimmunity: a systematic review

Chronic lymphocytic leukemia is frequently associated with immune disturbances. The relationship between chronic lymphocytic leukemia and autoimmune cytopenias, particularly autoimmune hemolytic anemia and immune thrombocytopenia, is well established. The responsible mechanisms, particularly the role of leukemic cells in orchestrating the production of polyclonal autoantibodies, are increasingly well understood. Recent studies show that autoimmune cytopenia is not necessarily associated with poor prognosis. On the contrary, patients with anemia or thrombocytopenia due to immune mechanisms have a better outcome than those in whom these features are due to bone marrow infiltration by the disease. Moreover, fears about the risk of autoimmune hemolysis following single agent fludarabine may no longer be appropriate in the age of chemo-immunotherapy regimens. However, treatment of patients with active hemolysis may pose important problems needing an individualized and clinically sound approach. The concept that autoimmune cytopenia may precede the leukemia should be revisited in the light of recent data showing that autoimmune cytopenia may be observed in monoclonal B-cell lymphocytosis, a condition that can only be detected by using sensitive flow cytometry techniques. On the other hand, there is no evidence of an increased risk of non-hemic autoimmune disorders in chronic lymphocytic leukemia. Likewise, there is no epidemiological proof of an increased risk of chronic lymphocytic leukemia in patients with non-hemic autoimmunity. Finally, since immune disorders are an important part of chronic lymphocytic leukemia, studies aimed at revealing the mechanisms linking the neoplastic and the immune components of the disease should help our understanding of this form of leukemia.

Systemic lupus erythematosus and chronic lymphocytic leukemia: rare coexistence in three patients, with comments on pathogenesis

We describe three patients with coexistent chronic lymphatic leukemia (CLL) and systemic lupus erythematosus (SLE). In two patients, the CLL was present before or coexistent with the SLE when the SLE was diagnosed, while in the third, the CLL developed 5 years after the diagnosis of SLE was first made. Although the association of autoimmune diseases and lymphoproliferative disorders is well established, only a few patients with coexistent CLL and concomitant SLE have been reported. The possible pathogenesis of this rare association is discussed.

Autoimmunity and malignancy

In patients with autoimmune diseases malignancy is observed more frequently than in an age-matched control group. In strains of mice susceptible to autoimmune diseases, the incidence of lymphoreticular malignancies is increased. Although viruses have not been directly implicated in their pathogenesis or etiology, there are suggestions that slow viruses may be involved. Viruses have been found to be important in the development of lymphomas. Hence in genetically susceptible animals, viruses can initiate the autoimmune process. Prolonged stimulation of the autoimmune process or a prolonged state of immunodeficiency could trigger or activate genes or their products, which could result in the development of malignancy.