ABSTRACT
Background: Identification of plasma cells into abnormal (APC) and normal (NPC) compartments is of utmost importance in flow cytometric (FC) analysis of multiple myeloma (MM) and related plasma cell dyscrasias for diagnosis, prognosis, and follow-up. No single phenotypic marker is sufficient to distinguish NPC from APC. Materials and Methods: 43 newly diagnosed cases of MM and 13 controls were included in the study. Bone marrow (BM) samples from the 2nd pass were processed on the same day with antibodies against CD38, CD138, CD19, CD81, CD45, CD117, CD200, CD56, cytoKappa, and cytoLambda in a 4-color experiment with CD38 and CD138 as gating antibodies. Results: Mean APC% in cases was 96.5%. The expected Immunophenotype (IP) of APC which is CD19-/56+/45-/81-/117+/200+ was found in only 13/43 MM cases. In 30/43 cases, APC revealed deviation from expected IP either for single or a combination of markers. Sensitivity for APC detection was highest for CD19 (95.2%) followed by CD56 (90.4%) and CD81 (83.7%). Specificity was highest for CD19 (100%), CD56 (100%), and CD81 (100%) followed by CD117 (92.3%). Combination of markers with maximum sensitivity to detect APC (97.6%) was CD81- or CD19- and CD200+ or CD56+ (two markers); and for NPC (92.3%) was CD81+ and CD19+ and CD56- (three markers). Conclusion: Plasma cell IP can be highly variable with multiple minor subpopulations in both cases and normal controls. CD 19 and CD56 are highly informative markers for a 4-color experiment. Assessment of multiple markers in an 8–10 color experiment is more informative but the lack of advanced flow cytometers should not limit the use of FC in a 4-color approach. Our results emphasize that even basic equipment with limited fluorochrome can provide meaningful information if used appropriately.
ABSTRACT
BACKGROUND: The expression of the multidrug resistance-1 (MDR-1) gene which encodes p-glycoprotein, is recognized as a biological mechanism possibly contributing to treatment failure in patients with acute myeloid leukemia (AML). Recent studies indicate its association with poor risk factors such as cytogenetic pattern and surface phenotype of blasts. We analyzed the role of MDR-1 gene expression in 36 chemo-naive AML patients. METHODS: In 36 patients, clinical data were reviewed and compared to MDR-1 gene expression, immunophenotyping results on CD7 & CD34, cytogenetic pattern and other suggestive prognostic factors. RESULTS: Median follow-up period was 150 days. The MDR-1 gene expression was observed in 19 out of 36 patients (52.8%). Significant correlation between MDR-1 gene and CD7 & CD34 expression was found. Sixteen out of 17 (94.1%) MDR-1 negative patients harbored favorable cytogenetic patterns, where as 11 out of 19 (57.9%) MDR-1 positive patients had favorable cytogenetic patterns. MDR-1 gene expression was not correlated to disease free survival (DFS), nor overall survival (OS) statistically although it has shown significant correlation to complete remission (CR) rate (P =0.001). CONCLUSION: We found that lack of MDR-1 gene expression was exclusively associated to favorable cytogenetic patterns in our study. In order to clarify the relationship between the role of MDR-1 gene and clinical outcome or other prognostic features, including cytogenetic pattern, further larger studies would be necessary.