Silver stain for ringed sideroblasts. A sensitive method that differs from Perls' reaction in mechanism and clinical application

Improved method for assessing iron stores in the bone marrow

BACKGROUND

Bone marrow iron microscopy has been the "gold standard" method of assessing iron deficiency. However, the commonly used method of grading marrow iron remains highly subjective.

AIM

To improve the bone marrow grading method by developing a detailed protocol that assesses iron in fragments, in macrophages around fragments and in erythroblasts.

METHODS

A descriptive study of marrow aspirates of 303 children (aged 6-60 months) with severe anaemia and 22 controls (children undergoing elective surgery) was conducted at hospitals in southern Malawi (2002-04).

RESULTS

Using an intensive marrow iron grading method, 22% and 39% of cases and controls had deficient iron stores, and 40% and 46% had functional iron deficiency, respectively. Further evaluation of the iron status classification by the intensive method showed that functional iron deficiency was associated with significantly increased C-reactive protein concentrations (126.7 (85.6) mg/l), and iron stores deficiency with significantly increased soluble transferrin receptor concentrations (21.7 (12.5) mug/ml).

CONCLUSIONS

Iron assessment can be greatly improved by a more intense marrow examination. This provides a useful iron status classification which is of particular importance in areas where there is a high rate of inflammatory conditions.

Myelodysplastic syndromes in the elderly: the role of growth factors in management

Myelodysplastic syndrome (MDS) comprises a group of heterogeneous clonal bone marrow disorders leading to peripheral cytopenia(s) and hypercellular marrow in the majority of the patients. The morphology of the cell lines is characterized by dysplastic features in some or all cell lines. The FAB classification has divided MDS in five subgroups, namely (1) RA (refractory anemia); (2) RARS (refractory anemia with ring sideroblasts); (3) CMML (chronic myelomonocytic leukemia); (4) RAEB (refractory anemia with excess blasts); and (5) RAEB-T (refractory anemia with excess blasts in transformation). Myelodysplastic syndrome remains primarily a disease of the elderly. With a reported median age of 74.4 years, patients have a chronic relentless course with complication of cytopenias, and a significant number of MDS patients, especially from the RAEB and RAEB-T categories, end up in acute myeloid leukemic transformation. Cytogenetic abnormalities are present in 40-58% of the cases and can provide not only help in diagnosis, but also understanding regarding the clinical course and prognostic aspect. Management of MDS is quite pragmatic and at this stage far from satisfactory. Various modalities have included use of differentiating agents, aggressive chemotherapy, bone marrow transplant and, more recently, significant interest has been generated in the use of hematopoietic growth factors. Differentiating agent trials have been unrewarding so far; chemotherapy trials have resulted in less benefit and more early toxic deaths, especially in the elderly MDS patients where the disease predominates. Bone marrow transplant appears suitable for some patients who are at a younger age. Salvation from this disease is being searched in the proper usage of hematopoietic growth factors and cytokines. There has been concern, however, that usage of growth factors has led to early and enhanced transformation of these patients to frank acute leukemic states. This concept appears to be somewhat refuted by newer controlled trials with GM-CSF and G-CSF, emphasizing that the acute leukemic transformation is the natural course of the disease and is not hastened by growth factor use. Preliminary studies are also suggesting that a combination of growth factors, especially G-CSF and erythropoietin as compared to chemotherapies, could be more beneficial in prolonging the survival of MDS patients who have progressed to the acute leukemic phase. More studies are needed for the understanding of the pathogenetic mechanism(s) in order to facilitate a more suitable and appropriate management strategy for MDS.

A technique for assessing the effects of pH and photodegradation on the stability of the iron chelate of ethyl N-methyl-4-hydroxy-5-oxo-3-pyrroline-3-carboxylate

Ethyl N-methyl-4-hydroxy-5-oxo-3-pyrroline-3-carboxylate forms a deep red chelate with iron salts. The color intensity is directly related to the iron concentration. The photostability of the red color was determined at pH 1.2 and 5 by spectrophotometric assay at 484 nm at intervals during irradiation by tungsten light at 1020 microW/cm2. After 528 hr of continuous irradiation in deionized water, 90.9% of the iron chelate had decomposed. The reaction followed zero order kinetics. Maximal stability was observed at pH 5 at both 10(-1) and 10(-2) molar concentrations of the iron chelate; no detectable decomposition occurred after 192 hr of continuous irradiation. The iron chelate in biological tissues is stable for 18 months. The staining technique is superior to other histological methods for estimating low concentrations of iron in tissue.

Combined silver Perls's stain for differential staining of ringed sideroblasts and marrow iron

During a study of nucleolar organiser regions, a modified silver stain was found to be a sensitive marker for the iron in ringed sideroblasts, more so than Perls's stain when the marrow iron stores were low. To enhance the usefulness of the silver stain, a combined silver Perls method was developed. This stains the ringed sideroblast iron black and haemosiderin blue, thus rendering the detection of ringed sideroblasts easier even when marrow iron stores are excessive. AT the same time, it allows marrow iron content to be evaluated. The silver reagent in this combined method probably shows phosphate rather than the iron present in the abnormal mitochondria in ringed sideroblasts. This facilitates the differential staining of ringed sideroblast "iron" and haemosiderin.