UChicago Medicine Medical Laboratories

This branch of pathology studies abnormalities of red blood cells, leukocytes, and platelets, as well as the organs where these cells originate and reside. Our hematopathologists evaluate peripheral blood smears, bone marrow specimens, and lymphoid tissue found in not only lymph nodes but also other organs. We help you evaluate why a patient has abnormal blood counts, enlarged lymph nodes, or an abnormal collection of hematopoietic cells in other tissues. We use traditional microscopy in conjunction with immunohistochemistry, flow cytometry, cytogenetics, and molecular diagnostic studies to reach an accurate diagnosis.

Flow cytometry uses visible light scatter and antibody linked fluorescent light emission to quantify the physical and antigenic properties of individual cells in a fluid stream as they pass single file through an analytical laser light source. In the flow cytometry section of the hematology laboratory, two five-color Beckman Coulter FC500 cytometers are used to analyze fresh peripheral blood, bone marrow, tissue, and body fluid specimens. Both surface and cytoplasmic antigen expressions are measured.

The scope of testing includes:

• The measurement of CD4 (T helper/inducer cell) absolute counts and the relative and absolute number of other lymphoid cell types in the evaluation of primary or secondary immune deficiency
• Hematopoietic stem cell (CD34) analysis to evaluate stem cell procurement for transplantation
• Leukemia and lymphoma phenotyping for diagnosis
• Paroxysmal nocturnal hemoglobinuria (PNH) evaluation
• Fetal hemoglobin quantitation
• Minimal residual disease detection and quantification

A pathologist’s interpretation and diagnosis are included with the leukemia and lymphoma phenotyping, paroxysmal nocturnal hemoglobinuria (PNH) evaluation, and minimal residual disease detection and quantification.

Our immunohistochemistry laboratory performs both immunohistochemistry (IHC) staining and in situ hybridization (ISH) on paraffin tissue sections and, for some antibodies, IHC on frozen tissue sections.

IHC is a technique for identifying cellular or tissue constituents (antigens) by means of antigen-antibody interactions. The site of antibody binding is identified either by direct labeling of the antibody or by the use of a secondary enzymatic labeling method. The enzymatic label (horseradish peroxidase (HRP) or alkaline phosphatase) allows visualization of the bound antibody by light microscopy in the presence of a suitable chromogenic substrate system.

ISH is a technique used to identify specific nucleic acid sequences (DNA or RNA) within the cells using targeted molecular probes; the site of hybridization signals are identified by demonstration of tags inserted into probes by use of secondary IHC chromogenic labeling methods.

The Immunohistochemistry Laboratory includes a repertoire of over 220 IHC antibodies for various targets, including CD antigens, tumor markers, hormone receptors, DNA mismatch repair enzymes, and multiple ISH probes, including EBER, kappa and lambda immunoglobulin light chains, and HPV (high-risk and low-risk types). The laboratory uses multiple staining platforms, including Leica Bond Max, Ventana Benchmark XT, and Dako Autostainer, and a polymer-based HRP or alkaline phosphatase detection system. The laboratory also performs double staining and multiplex staining for some tumor markers (KI67/Melan A, PIN-4).

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