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[A case of neuroblastoma with abnormal LD isoenzyme]
M Shibayama1, M Nagahara, H Horita
1Department of Clinical Laboratory, Kanazawa University Hospital.
Insights
This study identified an abnormal lactate dehydrogenase (LD) isoenzyme, LD2 extra band (LD2 ex), in a neuroblastoma patient. This tumor-produced LD2 ex marker rapidly decreased with chemotherapy, indicating its potential as a treatment response indicator.
Area of Science:
- Biochemistry
- Oncology
- Clinical Chemistry
Background:
- Lactate dehydrogenase (LD) is a key enzyme in cellular metabolism, and its isoenzyme patterns can provide diagnostic and prognostic information in various diseases.
- Neuroblastoma, a pediatric cancer, often exhibits altered metabolic profiles, but specific tumor-derived enzyme markers are not well-established.
Observation:
- A patient with neuroblastoma presented with exceptionally high total LD activity and an unusual LD isoenzyme pattern, including an elevated LD1 and a novel LD2 extra band (LD2 ex).
- The LD2 ex was not detected in the patient's erythrocytes, ruling out genetic causes, and immune complexes were excluded as a cause.
- Analysis of a metastatic lymph node revealed elevated LD1 before treatment and a shift to LD3 predominance with LD2 ex absence after chemotherapy.
Findings:
- The abnormal LD isoenzyme, LD2 ex, was strongly associated with the neuroblastoma tumor.
- The rapid decrease in total LD activity, LD1 fraction, and disappearance of LD2 ex following chemotherapy suggest these changes are directly linked to tumor burden and response.
- The findings indicate that LD2 ex is likely an abnormal isoenzyme produced by the tumor cells.
Implications:
- The tumor-specific LD2 ex isoenzyme may serve as a novel biomarker for monitoring neuroblastoma treatment response.
- Further research into the characterization and clinical utility of LD2 ex in neuroblastoma and other cancers is warranted.
- Understanding tumor-specific enzyme alterations can lead to improved diagnostic and therapeutic strategies in oncology.
Abstract:
We encountered a patient with neuroblastoma showing remarkably high total LD activity (12,585 IU/l). His liver and heart function was normal. In the serum LD isoenzyme pattern, LD1 was increased, and LD2 extra band (LD2 ex) was observed on the negative pole side of LD2. However, LD2 ex was absent in erythrocytes of the patient, which demonstrates the exclusion of genetic factors. Neither the enzyme counter current method or immunofixation showed immune complexes, excluding anomalies. The LD isoenzyme in a metastatic lymphnode lesion before treatment showed increased LD1. The LD isoenzymes in the tissue, removed after 5 courses of chemotherapy, showed predominance of LD3 and absence of LD2 ex. Rapid decreases in the serum total LD activity and LD1 fraction and the disappearance of LD2 ex after chemotherapy suggest that these changes in the two LD fractions are associated with production of abnormal LD (LD2 ex) by the tumor.