. Dilated cisternae of the ER resembling Rus-

The CD44 cell surface proteoglycan participates in a variety of CD44v6 has been also described in high-grade, but not in functions including lymphohematopoiesis, lymphocyte homing low-grade, non-Hodgkin's lymphomas. [25][26][27] and tumor metastasis. In addition to the standard form Upon interaction with its natural ligand, or when ligated by addition to these clinical and biological parameters, serum

The liver of the neonatal mouse continues to show haematopoietic activity for up to 2 weeks after birth and morphological analysis has shown that this activity becomes focused in discrete haematopoietic colonies by the end of the first week postnatal. Furthermore, each colony contains cells of one haematopoietic lineage only, that is, erythroid, myeloid or pre-B-lymphoid cells. This pattern of differentiation suggests that each colony is derived from a single committed precursor cell, which, if true, would represent the first demonstration of non-mixed haematopoietic colonies in normal development and would provide a useful system for studying the factors affecting the clonal diversity of haematopoietic stem cells and their lineage-committed progeny. Here we have analysed the haematopoietic foci in the liver of neonatal mouse chimaeras, using a newly developed ubiquitous in situ cell marker system which clearly demonstrates the clonal origin of these colonies.

Large granular lymphocytes (LGL) are defined as nonadherent mononuclear cells with cytoplasmic azurophilic granules, avid receptors for the Fc portion of IgG, and cytotoxic functions (NK or ADCC activities). In the present study, the granules of LGL isolated from human peripheral blood have been analyzed by enzyme cytochemistry and electron microscopy. It had been found that: (1) in the single cells, granules at different stages of maturation could be detected: in addition, packaging of the granules took place in the proximity of the Golgi apparatus, which is similar to that seen in secretory cell types. (2) Acid phosphatase (AP) was observed within the granules and the vesicles located in the Golgi area: the Golgi apparatus identified through its thiamine pyrophosphatase-positivity was consistently negative for AP. (3) Alpha naphthyl-acetate esterase (ANAE) activity was localized in the granules as well as on the membrane of LGL and monocytes. (4) The ANAE activity of LGL was of the monocytic and not of the lymphocytic type, as shown by NaF inhibition. (5) The LGL granules, although identifiable as primary lysosomes, were not involved in the process of phagocytosis, since LGL failed consistently to ingest latex particles or opsonized red cells.

Expression of surface adhesion molecules of the Ig superfamily (CD54 and CD58), of the integrin family (beta 1, beta 2, and beta 3 chains), of the selectin family (L-selectin), and of the lymphocyte homing receptor (CD44) was analyzed on B-cell chronic lymphocytic leukemia (B- CLL) cells from 74 patients. The aim of the study was the definition of phenotypically distinct disease subsets and the correlation of adhesion molecule phenotypes with clinical parameters. Expression of CD58 on B- CLL cells defined more advanced disease stages. In comparison with beta chain-positive cases, patients whose cells did not express beta 1, beta 2, and beta 3 integrin chains fell into the most favorable prognostic group, with lower lymphocytosis and the absence of splenomegaly, diffuse bone marrow infiltration, and therapy requirement. A novel finding was the expression of beta 3 chains on cells from a minority (12 of 74) of B-CLL cases. beta 3 chains were always coexpressed with beta 1 and beta 2 chains. Two-color immunofluorescence analyses of adhesion molecules such as alpha x beta 2 integrin (LeuM5) and L- selectin (Leu8) showed that these markers were detectable on variable proportions of leukemic cells, thus confirming the intraclonal phenotypic heterogeneity of B-CLL. Differences in the intensity of CD44 expression were also shown among the various B-CLL clones. Finally, no major variations were shown by comparison of adhesion molecule phenotypes of leukemic cells simultaneously obtained from blood and bone marrow, and of CD5+ versus CD5- clones.