Summary & Conclusion
This case control study was carried out on 64 subjects (32 lymphoproliferative disorders patients and 32 apparent healthy subjects) patients with hematologic malignancies (ALL, CLL, hairy cell leukemia, mantle cell lymphoma and multiple myeloma) who presented to Assiut university hospitals. The following investigations were done:
1. Full clinical evaluation including:
· Full history taking including: age, sex, main complaint, anemic manifestations, therapeutic history and history of blood transfusion.
· Clinical examination including: fever, hepatomegaly, splenomegaly, lymphadenopathy, bleeding tendency and bone tenderness.
2- Laboratory investigations include:
a- Complete blood count (CBC): Two ml of venous blood were withdrawn into ethylene diamine tetra acetic acid (EDTA) used immediately for complete blood counting with spreading of peripheral blood smears for Leishman staining and differential leucocytic counting. CBC was done using ADVIA 2120i (Siemens, Germany), including hemoglobin (Hb) level, RBCs indices, total leukocytic count, differential leukocytic count, platelet count and reticulocytic count. Examination of peripheral blood smears stained with Leishman stain for differential leukocytic count and detection of abnormal cells.
b- Bone marrow Aspirate (BMA):
sample was collected in EDTA tube for each patient from the anterior or posterior superior iliac spine, half ml of BM aspirate was mixed immediately on glass slides, and smears were spread to be examined after staining by Leishman stain. One ml of BM aspirate was gently dispensed into an EDTA solution tube for Flow cytometry (FCM) immunophenotypic analysis. The sample used for FCM was evaluated within 24 hours and stored at 4-8°C in the refrigerator up to 72 hours. Examination of Leishman-stained BM aspiration smears for assessment of BM cellularity, morphological BM proliferation, and BM differential counting.
c- Immunophenotyping: was done by Beckman coulter cytoflex flow cytometer using monoclonal antibodies (MAbs).
CD19 complex was expressed by lymphoproliferative disorders with variable density of expression of its members and correlates with clinical data, morphologic subtypes, disease course and overall prognosis.
The expression of the four members of CD19 complex (presented as the percentage of cells expressing each molecule) was higher in B-lymphoproliferative disorders as expected because lymphocytes have a proliferative capacity in contrast to the control group in which lymphocytes are mature and resting cells that do not proliferate.
We found that CD19 is widely expressed during all phases of B cell development until terminal differentiation into plasma cells. The majority of B cell malignancies express normal to high levels of CD19.
It seems that CD19 and CD21 are the two members of the complex that are most consistently co-expressed on B cells. Also, there was a positive correlation between lymphocytic count and CD21 expression, possibly due to the presence of activated B cells in LPDs.
CD81 showed no wide difference of expression between most of cases in this study. These results indicate that CD81 expression can be featured as a robust marker for leukemic blasts in cases of B-ALL and can be exploited as a valuable addition to flow cytometric monitoring of MRD.
The decreased level of expression of CD225 can be used as an early predictive marker of transformation in chronic lymphocytic leukemia.
We analyzed a total of 171 cases of hematologic malignancies, 167 cases with acute myeloid leukemia and 4 cases with T-acute lymphoblastic leukemia. None of the analyzed cases showed ectopic expression of any of the members of CD19 complex.
In conclusion, this study showed that the four members of CD19 complex are not always physically associated on the B cell surface, neither on the normal nor on the malignant B cells. The statement of association of the all complex members applies only to three of them, namely CD19, CD21 and CD81 but CD225 shows association with the members in about 60% of cases.
