Immunophenotypic changes between diagnosis and relapse in childhood acute lymphoblastic leukemia.

To get more insight into the phenotypic changes of childhood acute lymphoblastic leukemia (ALL) at relapse, a detailed morphological and immunophenotypic study in 40 childhood ALL cases (32 precursor B-ALL and 8 T-ALL) was performed. Expression patterns of non-lineage specific markers (terminal deoxynucleotidyl transferase (TdT), CD34, and HLA-DR), B-lineage markers (CD10, CD19, CD20, and CD22), T-lineage markers (CD1, CD2, CD3, CD4, CD5, CD7, and CD8), and cross-lineage myeloid markers (CD14, CD15, and CD33) were compared at diagnosis and relapse. In case of low blast counts (< or = 70%) at relapse, double labeling for membrane markers and TdT was used in order to define the precise immunophenotype of the TdT+ leukemic cells. An immunological marker-shift was defined as either a conversion from positive to negative and vice versa or a difference in positivity of > or = 50%. Morphological differences between diagnosis and relapse were detected in 34% of precursor B-ALL and 14% of T-ALL. Differences in immunological marker expression were found in 72% of precursor B-ALL and in 75% of T-ALL, and generally concerned minor shifts with loss or acquisition of a few markers. The morphological shifts and immunophenotypic shifts were not correlated. Immunophenotypic shifts were found for all markers tested in precursor B-ALL, except for HLA-DR. Shifts in CD10 expression (16% of cases) were only observed in relapses occurring 30 months or more after diagnosis. In four precursor B-ALL an intra-lineage shift was found at relapse (one common ALL to null ALL and three pre-B-ALL to common ALL or null ALL) and two precursor B-ALL cases were diagnosed as acute non-lymphocytic leukemia at relapse based on morphology and immunophenotype. In T-ALL, neither intra-lineage nor inter-lineage shifts were observed, although shifts were detected in all T cell markers tested, except for the lineage specific CD3 and T cell receptor (TcR) markers. In conclusion, immunophenotypic shifts at relapse frequently occur in precursor B-ALL and T-ALL, in a small percentage leading to an intra-lineage shift (10%) or inter-lineage shift (5%). Therefore immunophenotypic monitoring of minimal residual disease in ALL patients should be based on multiple marker combinations, preferably together with polymerase chain reaction analysis of rearranged immunoglobulin and/or TcR genes or chromosome aberrations.

Prognostic significance of peanut agglutinin binding in childhood acute lymphoblastic leukemia.

We previously reported the favorable prognosis associated with positive peanut agglutinin (PNA) binding in childhood T cell acute lymphoblastic leukemia (ALL), and hypothesized that this may be related to glucocorticoid sensitivity (Veerman et al. Cancer Res 1985, 45: 1890). The purposes of this prospective study involving 202 children with newly diagnosed ALL were to determine the relationship between PNA binding and (1) immunophenotype; (2) in vitro resistance to prednisolone (PRD) and dexamethasone and other drugs; (3) clinical response to a systemic PRD monotherapy (plus one intrathecal injection with methotrexate); and (4) multidrug chemotherapy. PNA positivity was more frequent in T cell ALL (65% of 43 cases) than in pro-B (0% of seven cases), common (17% of 106 cases) and pre-B (16% of 45 cases) ALL (P < 0.001). PNA binding was not associated with in vitro resistance to PRD or dexamethasone. However, in 38 evaluable T cell ALL patients, nine of 13 PNA-negative cases were clinically poor responders to PRD, while all 25 PNA-positive cases were good responders to PRD clinically (P < 0.0001). The four clinically poor PRD responders with B cell precursor (BCP)-ALL were also PNA negative. Within T cell ALL, PNA-positive patients had a 3.4-fold (95% Cl, 1.1-10.4, P = 0.03) lower relative risk of any event, than PNA-negative patients. Within BCP-ALL, PNA binding was not of prognostic significance. In conclusion, PNA positivity, especially frequent in T cell ALL, is a marker for a subgroup of childhood ALL patients who are very likely to respond well to systemic PRD 'monotherapy'. In addition, PNA positivity is a favorable prognostic factor in T cell ALL.

Diagnosis of meningeal involvement in childhood acute lymphoblastic leukemia: cytomorphology and TdT.

Between December, 1984, and May, 1986, 98 CSF samples were sent to a central laboratory by postal express. The samples could be kept in a medium for up to 24 hours after the lumbar puncture. The quality of the cells proved to be good. Excluded were 5 samples delayed in delivery and 13 samples contaminated with blood, defined as the macroscopical presence of blood. The microscopical presence of erythrocytes in the cytocentrifuge preparation can make interpretation of the results difficult. Especially when leukemic blasts are present in the blood, extreme caution is necessary. A total of 71 samples could be studied by cytomorphology as well as by TdT-IF. When cytomorphological leukemic blasts were present, this was confirmed by TdT-IF positivity in all cases. But in 6 of 71 samples, TdT-IF was positive without the presence of cytomorphological leukemic blasts. Follow-up of these patients will show whether the therapeutic regimen has to be changed.

Regenerating normal B-cell precursors during and after treatment of acute lymphoblastic leukaemia: implications for monitoring of minimal residual disease.

We studied 57 childhood acute lymphoblastic leukaemia (ALL) patients who remained in continuous complete remission after treatment according to the Dutch Childhood Leukaemia Study Group ALL-8 protocols. The patients were monitored at 18 time points during and after treatment [640 bone marrow (BM) and 600 blood samples] by use of cytomorphology and immunophenotyping for the expression of TdT, CD34, CD10 and CD19. Additionally, 60 BM follow-up samples from six patients were subjected to clonality assessment via heteroduplex polymerase chain reaction (PCR) analysis of immunoglobulin VH-JH gene rearrangements. We observed substantial expansions of normal precursor B cells in regenerating BM not only after maintenance therapy but also during treatment. At the end of the 2-week intervals after consolidation and reinduction treatment, B-cell-lineage regeneration was observed in BM with a large fraction of immature CD34+/TdT+ B cells. In contrast, in regenerating BM after cessation of maintenance treatment, the more mature CD19+/CD10+ B cells were significantly increased, but the fraction of immature CD34+/TdT+ B cells was essentially smaller. Blood samples showed a profound B-cell lymphopenia during treatment followed by a rapid normalization of blood B cells after treatment, with a substantial CD10+ fraction (10-30%). Heteroduplex PCR analysis confirmed the polyclonal origin of the expanded precursor B cells in regenerating BM. This information regarding the regeneration of BM is essential for the correct interpretation of minimal residual disease studies.