We measured the concentration of CD33 antigen on the surface of cells in 315 bone marrow (BM) samples and 114 corresponding peripheral blood (PB) samples from patients with various leukemias (acute myeloid leukemia [AML], chronic myelogenous leukemia [CML], myeloproliferative disorder [MPD] other than CML, myelodysplastic syndrome [MDS]) and from control subjects. Overall CD33 intensity in total CD33+ cells was significantly higher in BM than in PB. CD33 intensity in total BM CD33+ cells differed significantly with the type of disease. The median number of CD33 molecules per cell was highest in AML, followed by MDS, CML, and control subjects and lowest in MPD. When only CD34+/CD33+ cells were examined, CD33 molecules per cell were highest in CD34+ cells in AML and lowest in MPD (P = .027). Patients with AML or MDS younger than 60 years had significantly higher intensity of CD33 expression on CD34+ cells than patients 60 years or older. Levels of CD33 intensity did not correlate with cytogenetics in patients with AML or MDS. There was no correlation between CD33 intensity and response to therapy or overall survival in 35 patients treated with protocols including Mylotarg. These data demonstrate variation in CD33 intensity between various leukemias.

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The proto-oncogene c-kit encodes a transmembrane tyrosine kinase growth factor receptor. Stem cell factor, the receptor ligand, plays an important role in the development of certain neoplasms. c-kit is selectively and competitively bound by STI-571, a newly developed tyrosine kinase inhibitor. Several investigators report conflicting results concerning its expression, especially in malignant breast lesions. The objective of this study was to better characterize the expression of c-kit within the spectrum of breast epithelium (normal breast epithelium, nonneoplastic lesions, and breast carcinoma). Seventy-seven randomly selected breast tissue samples, each containing normal breast epithelium (21), invasive breast carcinoma (41), in situ breast carcinoma (29), papilloma (8), fibroadenoma (5), fibrocystic change (11), and/or metastatic breast carcinoma (4), were immunostained with polyclonal rabbit antihuman c-kit (Dako, Carpenteria, CA) at a dilution of 1:200. The staining was interpreted as negative if no cells were immunoreactive, weak positive if 5% of the cells were immunoreactive, and positive if more than 5% of the cells were immunoreactive. Appropriate positive and negative controls were used. The observed staining was cytoplasmic, with highlighting of the nuclear membrane. Normal breast epithelium was positive in all cases. More than half of the cases of hyperplastic changes and benign neoplasms (fibroadenoma and papilloma) were positive. Only 10% of invasive and in situ carcinomas showed positivity for c-kit. c-kit is consistently expressed in normal breast epithelium, variably expressed in benign breast lesions, and poorly expressed in breast carcinoma. These data suggest that c-kit may play a role in breast tumor progression and may therefore have diagnostic, prognostic, and therapeutic implications.

The status of the sentinel lymph node (SLN) has been shown to accurately reflect the presence or absence of metastases in the axilla in patients with breast cancer. This study was designed to determine the optimal protocol for SLN processing. A total of 173 SLNs from 96 breast cancer patients who had successful SLN localization and underwent completion axillary node dissection were identified. All SLNs were negative for metastases by initial routine histologic evaluation. The nodes were submitted in a total of 300 blocks. Each block was serially sectioned to produce 10 levels. Pan-cytokeratin stain was performed on levels 3 and 8. All other levels were stained with hematoxylin and eosin. Metastases were identified in 22 SLNs from 19 patients by examining all 10 levels. The first two hematoxylin and eosin- or the first cytokeratin-stained levels were positive for metastases in 21 (95.5%) of the 22 positive SLNs. Two additional hematoxylin and eosin-stained and one cytokeratin-stained levels of each SLN correctly identified the status of the node in 94 (97.9%) of 96 patients. Therefore, we recommend that after an initial hematoxylin and eosin-stained section, two additional hematoxylin and eosin-stained sections and one cytokeratin-stained section should be evaluated.

Stability of therapeutic drugs in sera collected in Becton-Dickinson VACUTAINER serum separator SST tubes has been well studied. Recently, the Greiner Vacuette serum separator tube has become available for blood collection. However, stability of therapeutic drugs in sera when the specimen is collected in the Greiner tube has not been reported. The authors studied the stability of 15 commonly monitored drugs in sera when stored on the gel of the Greiner serum separator tubes. The drugs studied were amikacin, gentamycin, tobramycin, vancomycin, digoxin, quinidine, theophylline, carbamazepine, phenobarbital, phenytoin, valproic acid, tricyclic antidepressants, salicylate, acetaminophen, and ethanol. The authors compared the concentrations of drugs in sera stored in plain tubes (no gel) and in sera stored in the Greiner tubes containing serum separator gel. They observed a significant decline in the concentrations of tricyclic antidepressants when stored in the Greiner tubes. Interestingly, concentrations of amitriptyline declined more than its metabolite nortriptyline and concentration of imipramine also decreased more than its metabolite desipramine. The concentration of carbamazepine also decreased slightly over time when serum was stored in the Greiner tube. Although declines in carbamazepine concentrations on prolonged storage in the Greiner tubes were statistically significant, the decreases may not be clinically significant. The concentrations of the other drugs studied did not decline when stored in the Greiner tubes. The authors conclude that the Greiner brand tube is not suitable for blood collection for analysis of tricyclic antidepressants.