Cell–cell and cell–matrix interactions, which are mediated by cell adhesion molecules, play a fundamental role during many cellular processes including growth, differentiation, cell migration and ...cancer metastasis. One molecule playing a major role in these processes is the CD44 surface receptor, which is expressed in a wide range of cells including many cells of the hemopoietic system, where it mediates the interaction with its major ligand, hyaluronate. However, little is known about CD44 and hyaluronate in bone marrow and this was investigated immunohistochemically in trephine biopsies and in cultivated human bone marrow stromal cells. In biopsy specimens, patches of hyaluronate deposition were detected in the extracellular matrix (ECM). However, most of the areas of the ECM were devoid of hyaluronate. Single mast cells and lymphocytes scattered throughout the marrow were CD44 immunopositive. Marrow-derived stromal cells (MDSC) expanded in cell culture were immunopositive for CD44, hyaluronate synthase, and hyaluronate. Hence, a marked difference between CD44 immunolocalisation and hyaluronate deposition can be observed between in situ and under cell culture conditions. Since in normal marrow in situ the number of CD44 immunopositive cells was low, interactions of CD44 and hyaluronate would appear to not to play a major role in cell adhesion in the normal bone marrow.
Basophils are highly specialized granulocytes that express a unique profile of antigens and increase in myeloproliferative disorders. In chronic myeloid leukemia (CML), basophilia is an independent ...prognostic variable. So far, however, no reliable immunohistochemical approach for routine-detection and enumeration of bone marrow (bm) basophils has become available. To overcome this disadvantage, we have applied the anti-basophil antibody 2D7 on formalin-fixed, paraffin-embedded sections of normal bm and bm from patients (pts) with chronic myeloid leukemia (CML; chronic phase, n=21; accelerated phase, n=9), other myeloproliferative disorders (idiopathic myelofibrosis IMF, n=3; polycythemia vera PV, n=7; essential thrombocythemia ET, n=7), and normal / reactive bm (n=32). As assessed by serial section-staining of bm specimens, the 2D7 antibody was found to be a basophil-specific immunohistochemical reagent. In serial bm sections, 2D7+ basophils co-expressed histidine decarboxylase, CD15, and CD43, but did not express B- or T-cell restricted antigens corresponding to the phenotype of normal blood basophils. Bm basophils were found to increase in number in pts with CML and other myeloproliferative disorders compared to normal bm (median 2D7+ cells/mm2 bm: normal bm: 7; CML: 46; IMF: 26; PV: 21; ET: 21, p<.05). The highest numbers of bm basophils were recorded in pts with accelerated phase CML (111 2D7+ cells/mm2). Together, we have established a useful immunohistochemical staining procedure for basophil detection in normal bm and pts with myeloid neoplasms. This approach should enable the quantification of basophils in these pts and the monitoring of bm basophil counts during follow up examinations and anti-leukemic therapies.
Synthesis of histamine in hematopoietic progenitor cells may be one of the earliest events in mast cell-development from pluripotent hematopoietic progenitor cells. In the present study, we asked ...whether the key enzyme involved in histamine generation, histidine decarboxylase (HDC), can be employed as an immunohistochemical marker for the detection of (neoplastic) mast cells (MC) in patients with cutaneous (CM) or systemic mastocytosis (SM). To address this question, we examined bone marrow biopsy specimens in a cohort of 101 patients (CM, n=10; indolent SM, n=46; SM with associated clonal non-MC lineage disease, n=31; aggressive SM, n=10; MC leukemia, n=3; MC sarcoma, n=1) using an antibody against HDC. Independent of the maturation stage of MC or subtype of disease, the anti-HDC antibody produced clear diagnostic staining results in all patients with bone marrow involvement examined including those with MC leukemia and MC sarcoma, in which MC are particularly immature and often escape analysis when examined by conventional stains. In these patients (MC leukemia, n=2; MC sarcoma, n=1), expression of HDC was reconfirmed at the mRNA level by RT-PCR analysis performed with RNA of highly enriched sorted CD117+ MC. In patients with CM or normal/reactive bone marrow (n=30), no HDC-positive infiltrates were detected. In these patients, only a few hematopoietic cells, presumably basophils, were found to react with the anti-HDC antibody. In summary, HDC is expressed in neoplastic bone marrow MC in patients with SM independent of the maturation stage of cells or the variant of disease. HDC should therefore be considered as a new MC marker in the screen panel of antigens employed to diagnose high grade MC malignancies.
