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Quantitative Phenotyping of Childhood Leukemia Identifies Variable and Invariable Cell Surface Antigens
D Kreindler1, D Petsche1, A Hrincu1
1a Divisions of Immunology Hospital for Sick Childrenj and Departments of Immunology and Pediatrics, University of Toronto, Toronto, Canada, M5G 1X8.
Insights
This study quantifies cell surface antigens in childhood leukemia using flow cytometry. Findings reveal distinct antigen profiles for acute lymphoblastic leukemia (ALL) and acute myeloblastic leukemia (AML), aiding in understanding leukemogenesis.
Area of Science:
- Immunology
- Hematology
- Oncology
Background:
- Childhood leukemia classification relies on cell surface antigen expression.
- Quantitative analysis provides deeper insights into leukemia subtypes.
Purpose of the Study:
- To quantitatively phenotype childhood leukemia cells by measuring cell surface antigen density.
- To correlate antigen expression patterns with leukemia subtypes and differentiation status.
Main Methods:
- Flow cytometry analysis of peripheral blood cells from 75 childhood leukemia cases.
- Quantification of cell surface antigens including CALLA (CD10), CD5, CD20, CD13, HLA-DR, and CD19 using relative fluorescence index (RFI).
Main Results:
- Distinct quantitative immunological phenotypes were derived for acute lymphoblastic leukemia (ALL) and acute myeloblastic leukemia (AML).
- CALLA (CD10) was highly expressed on non-T ALL groups III and IV (mean RFI 26.4).
- CD5 was present on T-ALL (RFI 4.5) but at low levels on immature non-T ALL (RFI 2.3).
- Non-T ALL exhibited high, variable levels of CALLA, HLA-DR, CD9, and CD44, and lower, consistent levels of CD19, CD38, and other markers.
- Invariable antigens remained consistent across different leukemia subtypes and differentiation stages.
Conclusions:
- Quantitative analysis of leukemia-associated antigens provides a detailed immunological profile.
- Variable antigens may reflect cell function, differentiation, or malignant alterations.
- Understanding these antigens is crucial for elucidating their role in leukemogenesis and disease progression.
Abstract:
Cells obtained from 75 cases of childhood leukemia were subjected to flow cytometry analysis to estimate the density of several cell surface antigens and derive a quantitative immunological phenotype. Sixty-five cases of acute lymphoblastic leukemia (ALL) including 10 T-ALL, 6 non-T ALL designated groups I and II (HLA-DRCALLA), 48 non-T ALL termed groups III and IV (HLA-DRCALLA) and one B-ALL were studied; 10 cases of acute myeloblastic leukemia (AML) were also analysed. The estimation of the relative fluorescence index (RFI) on leukemic blasts led to the derivation of mean values for each marker in the leukemia subgroups. We have quantitated the levels of the antigens generally used in the classification of these leukemias (CALLA, CD5, CD20, CD13, HLA-DR and CD19) and of other cell surface antigens associated with leukemic cells. For example, CALLA (CD10) level was high (mean RFI value of 26.4) on the leukemic cells of non-T ALL groups III and IV. The CD5 antigen was present on T-ALL, as expected, with an RFI value of 4.5; however, low levels were observed on the more immature non-T ALL of groups I and II (RFI = 2.3 on only 27% of blast cells). The quantitative analysis of the cell surface antigens associated with non-T ALL has revealed molecules such as CALLA, HLA-DR, CD9 and CD44 present at high and variable levels and others such as CD19, CD38, 44G4, 44D7, 44H9 and 44H6 generally of lower intensity, less variable from one patient to another, and with similar mean levels of expression in the different subgroups. These invariable antigens are not altered by the lineage or stage of differentiation of the leukemic cells. The variable antigens could be correlated with the functional and/or differentiation status of the cells and could also be modified by the alterations of regulatory processes associated with malignancy. The quantitation of multiple leukemia-associated antigens, whose structure and function are becoming rapidly established, should help in elucidating the function of these molecules in leukemogenesis and/or disease progression.
