Monoclonal B‐cell lymphocytosis (MBL) is a lymphoproliferative disorder characterized by clonal expansion of a B‐cell population in peripheral blood of otherwise healthy subjects. MBL is divided into ...CLL (chronic lymphocytic leukemia)‐like, atypical CLL‐like and non‐CLL MBL. The aim of this study was to evaluate immunophenotypic characteristics and clinical outcomes of MBL in kidney transplant (KT) recipients. We retrospectively evaluated 593 kidney transplant (KT) recipients in follow‐up at our center. Among them, 157 patients underwent peripheral blood flow cytometry for different clinical indications. A 6‐color panel flow cytometry was used to diagnose MBL. This condition was detected in 5 of 157 KT recipients. Immunophenotypic characterization of MBL showed four cases of non‐CLL MBL and one case of CLL‐like MBL. At presentation, median age was 65 years (range 61‐73). After a median follow‐up of 3.1 years (95%CI; 1.1‐5) from diagnosis, patients did not progress either to CLL or to lymphoma. The disorder did not increase the risk of malignancy, severe infections, graft loss and mortality among our KT recipients. Surprisingly, all cases were also affected by concomitant monoclonal gammopathy of undetermined significance, which did not progress to multiple myeloma during follow‐up. In conclusion, our data suggest that MBL is an age‐related disorder, with non‐CLL MBL being the most common subtype among KT recipients.
Lenalidomide is an immunomodulatory agent clinically active in CLL patients. The specific mechanism of action is still undefined, but includes the modulation of microenvironment. In CLL patients, ...nurse-like cells (NLCs) differentiate from CD14+ mononuclear cells and nurture/protect CLL cells from apoptosis. NLCs resemble M2 macrophages with potent immunosuppressive functions.
We examined the ability of lenalidomide to mediate a pro-inflammatory switch of NLCs affecting the protective microenvironment generated by CLL into tissues.
NLCs were generated in presence or absence of lenalidomide: cell surface markers, phagocytosis and induction of T cell proliferation were analyzed after 10 days. NLCs activation was measured using a yellow tetrazolium MTT assay after 5 days of culture and NLCs proliferation was measured by CFSE staining. Microarray-based gene expression profiles of NLCs treated or not with lenalidomide were evaluated after 10 days and data were confirmed by real time PCR.
Lenalidomide modifies the immunophenotype and the biological characteristics of NLCs. First, treatment with lenalidomide 0.5µM and 1µM increased the number of NLCs to 268% and 309% compared to untreated control (100%) respectively (p<0.05). To explain the high number of NLCs generated by lenalidomide, we analyzed cell activation and proliferation. We observed a strong increase in NLCs activation after treatment with lenalidomide that correlated with stimulation of NLCs proliferation from 44% to 55% (% of dividing cells) (p<0.05).
In contrast with the high number of NLCs generated in presence of lenalidomide, we found that NLCs lost the ability to nurture and protect CLL cell from apoptosis reducing their viability from 54.2% to 44.5% (p<0.05), but they strongly attracted CLL cells reaching an increase of adhesion to 227% and 212% with the addition of 0.5µM and 1µM lenalidomide (p<0.05). Accordingly with these results, we investigated the ability of lenalidomide to interfere with leukemia-promoting activity of NLCs. Lenalidomide improved the ability of NLCs to engulf zymogen particles to 141% and 155% with dosage of 0.5µM and 1µM compared to control (100%) (p<0.05), further confirmed analyzing the uptake of FITC-dextran by NLCs that increased to 252% and 356% compared to untreated control (p<0.01). Moreover lenalidomide strongly improved the ability of NLCs to induce T cells proliferation from 19.5% to 35.0% (% of dividing cells) (p<0.05). Lastly, gene expression profiling showed a switch to a pro-inflammatory profile in NLCs induced by treatment with lenalidomide involving a modulation of pivotal genes for the immune response, activation/proliferation of T cells, complement activation as well as regulation of cellular movement, cytokine and chemokine activation. In particular, down-regulation of CCL2, CXCL12, IL-10, CD163 and up-regulation of IL-2 were apparent.
Collectively, our data provide new insights into the mechanism of action of lenalidomide that reverts NLCs polarization from M2 to M1-skewed phenotype affecting the supporting and protective microenvironment generated by CLL into tissues.
Maffei:Celgene: support for travel to congresses Other. Marasca:Celgene: Honoraria, Research Funding.
Summary
Chronic/recurrent behaviour may be encountered in some distinct atypical or malignant lymphoproliferations, while recurrences are not generally observed in reactive/benign lymphadenopathies. ...We retrospectively analysed a consecutive series of 486 human immunodeficiency virus‐negative adults, who underwent lymphadenectomy. Neoplastic and benign/reactive histopathological pictures were documented in 299 (61·5%) and 187 (38·5%) cases, respectively. Of note, seven of the 111 (6·3%) patients with benign lymphadenopathy without well‐defined aetiology, showed chronic/recurrent behaviour, without constitutional symptoms. Enlarged lymph nodes were round in shape and hypoechoic, mimicking lymphoma. Reactive follicular hyperplasia and paracortical expansion were observed. Human herpesvirus (HHV)‐6B positive staining in follicular dendritic cells (FDCs) was documented in all seven patients. Serological, molecular and immunological examinations suggested HHV‐6B reactivation. Among the remaining 104 cases with reactive lymphoid hyperplasia in the absence of well‐known aetiology and without recurrences, positivity for HHV‐6B on FDCs was found in three cases, whereas in seven further patients, a scanty positivity was documented in rare, scattered cells in inter‐follicular regions. Immunohistochemistry for HHV‐6A and HHV‐6B was invariably negative on 134 lymph nodes, with either benign pictures with known aetiology or malignant lymphoproliferative disorders, tested as further controls. Future studies are warranted to investigate a potential association between HHV‐6B reactivation and chronic/recurrent benign lymphadenopathy.
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