The role of lymphoid tissue SPARC in the pathogenesis and response to treatment of multiple myeloma.

Background: Despite the significant progress in the treatment of multiple myeloma (MM), the disease remains untreatable and its cure is still an unmet clinical need. Neoplastic transformation in MM is initiated in the germinal centers (GCs) of secondary lymphoid tissue (SLT) where B cells experience extensive somatic hypermutation induced by follicular dendritic cells (FDCs) and T-cell signals. Objective: We reason that secreted protein acidic and rich in cysteine (SPARC), a common stromal motif expressed by FDCs at the origin (SLTs) and the destination (BM) of MM, plays a role in the pathogenesis of MM, and, here, we sought to investigate this role. Methods: There were 107 BM biopsies from 57 MM patients (taken at different time points) together with 13 control specimens assessed for SPARC gene and protein expression and compared with tonsillar tissues. In addition, regulation of myeloma-promoting genes by SPARC-secreting FDCs was assessed in in vitro GC reactions (GCRs). Results: SPARC gene expression was confirmed in both human primary (BM) and secondary (tonsils) lymphoid tissues, and the expression was significantly higher in the BM. Sparc was detectable in the BM and tonsillar lysates, co-localized with the FDC markers in both tissues, and stimulation of FDCs in vitro induced significantly higher levels of SPARC expression than unstimulated controls. In addition, SPARC inversely correlated with BM PC infiltration, ISS staging, and ECOG performance of the MM patients, and in vitro addition of FDCs to lymphocytes inhibited the expression of several oncogenes associated with malignant transformation of PCs. Conclusion: FDC-SPARC inhibits several myelomagenic gene expression and inversely correlates with PC infiltration and MM progression. Therapeutic induction of SPARC expression through combinations of the current MM drugs, repositioning of non-MM drugs, or novel drug discovery could pave the way to better control MM in clinically severe and drug-resistant patients.

The potential association of CMV-specific CD8+ T lymphocyte reconstitution with the risk of CMV reactivation and persistency in post allogeneic stem cell transplant patients.

OBJECTIVES: development of cytomegalovirus (CMV)-specific CD8+ T cell response is crucial in preventing symptomatic CMV infection specially, in stem cell transplant (SCT) patients. The aim of this study was to evaluate CMV-specific CD8+ T cell reconstitution in allogeneic SCT recipients and to study the possible association between CMV-specific CD8+ T cell recovery with protection from CMV reactivation and persistency. METHODS: Human leuKocyte antigen (HLA)-tetramers were used for CMV-specific CD8+ cell quantitation by Flow cytometry in twenty post-allogeneic SCT patients. RESULTS: Nine patients (45%) developed rapid recovery of CMV-specific CD8+ cells, among them; 7 patients (78%) had no CMV reactivation in the first 95 days post-transplant. Five patients had developed persistent CMV viremia; all of them had not developed CMV-specific CD8+ recovery till day 95 post-transplant. Patients with persistent CMV viremia had a statistically significant lower means of CMV-specific CD8+ percent and absolute count compared to those without persistent viremia (p = .001, .015), respectively. DISCUSSION: The incidence of CMV reactivation and persistency was higher among patients with delayed CMV-specific CD8+ reconstitution in the first 95 days post-transplant. CONCLUSION: CMV-specific CD8+ cells can help in categorizing patients into risk groups: (early recovery/low risk) and (delayed recovery/increased risk), this tool may guide clinicians in the selection of patients who may profit from prophylactic antiviral therapy and frequent viral monitoring.

HLA alloimmunization in Egyptian aplastic anemia patients receiving exclusively leukoreduced blood components.

BACKGROUND: The aim of the work was to detect the presence of anti-human leukocyte antigens (anti-HLAs) class I and II antibodies in sera of multitransfused aplastic anemia pediatric patients using two different techniques. The effect of the implemented transfusion practice on the frequency of these antibodies was studied as well as their effect on the patient's clinical condition. METHODS: Flowcytometry panel reactive antibodies (FlowPRAs) for HLA class I and II were determined and compared to the results obtained by Complement-dependent-cytotoxicity (CDC) assay. RESULTS: Over the past 3years, 20 aplastic anemia patients received leukoreduced blood components, 5/20 patients received leukoreduced products exclusively throughout their disease (group1), 15/20 patients had received non-leukoreduced components previously (group2). None of the patients in group1 was FlowPRA positive. Six patients from group2 (40%) were FlowPRA positive, only four out of these six patients showed positive CDC test. Positive and negative predictive values of CDC were 44.4 and 81.4% respectively, with 65% accuracy. Platelet refractoriness was encountered in 13/20 patients; only 3 out of these 13 patients (23%) were FlowPRA I positive (38±18%). One refractory patient died from intracranial hemorrhage. His FlowPRA I was 65.7% and CDC assay failed to detect it. CONCLUSION: Leukoreduction of blood components minimizes the incidence of HLA alloimmunization. Further investigations for other immune causes of platelet refractoriness are recommended. FCM is a simple and reliable technique for detection of anti-HLA antibodies, while CDC assay lacks sensitivity and specificity.

CD200 expression in B-cell chronic lymphoproliferative disorders.

BACKGROUND: Flow cytometry immunophenotyping (FCIP) is used for rapid, specific diagnosis of B-chronic lymphoproliferative disorders (BCLPDs). However, cases may deviate from the typical immunophenotype; therefore, there is a need for adding new marker(s) for differentiating BCLPDs.Lately, few researches highlighted CD200 expression in some BCLPDs. Our aim was to evaluate CD200 expression in different BCLPDs and whether adding CD200 to BCLPD-FCIP routine panels could improve the ability of their differential diagnosis. METHODS: We evaluated CD200 expression in 49 BCLPD patients and 26 age- and sex-matched control subjects. Flow cytometry immunophenotyping first panel included CD5, CD19, sIg, CD23, CD22, CD79b, and FMC7; for BCLPDs other than chronic lymphocytic leukemia (CLL) and mantle cell lymphoma, CD11c, CD103, CD25, and CD10 were evaluated. RESULTS: Using tricolor FCIP, CD200 showed high bright expression on CD5/19-positive clone in all B-CLL patients (100%), with a mean of 94% (SD, 11%); in the 2 cases of hairy cell leukemia, CD200 was brightly expressed on 96% and 99% of cells. In all other BCLPDs including mantle cell lymphoma, follicular lymphoma and splenic marginal zone lymphoma, CD200 expression (on CD19/22-positive cells) was less than 20% with a mean of 10% (SD, 8%) and a dim pattern. CD200 expression was significantly higher in CLL compared with non-Hodgkin lymphoma groups (P < 0.001). CONCLUSIONS: Evaluating CD200 expression has a great impact on accurate BCLPDs diagnosis and could be added to the BCLPD routine panels. The high expression of CD200 in B-cell CLL and hairy cell leukemia could open the option for targeted immune (anti-CD200) therapy.