Widespread Expression of Chondroitin Sulfate-type Serglycins with CD44 Binding Ability in Hematopoietic Cells

Abstract

Serglycin is a family of small proteoglycans with Ser-Gly dipeptide repeats and is modified with various types of glycosaminoglycan side chains. We previously demonstrated that chondroitin sulfate-modified serglycin is a novel ligand for CD44 involved in the adherence and activation of lymphoid cells. In this study, we investigated the production and distribution of CD44 binding serglycins in various hematopoietic cells and characterized their carbohydrate side chains. Immunoprecipitation analysis using CD44-IgG and polyclonal antibody against the serglycin core peptide demonstrated that various serglycin species capable of binding CD44 are produced by a variety of hematopoietic cells including lymphoid cells, myeloid cells, and a few tumor cell lines. Glycosaminoglycans on these serglycins, which are essential for CD44 binding, are composed of chondroitin 4-sulfate or a mixture of chondroitin 4-sulfate and chondroitin 6-sulfate, but no heparin or heparan sulfate side chain was detected. The serglycins are also secreted by normal splenocytes, lymph node lymphocytes, and bone marrow cells, whereas they are secreted in very small amounts by normal thymocytes. Secretion of serglycins is greatly enhanced by mitogenic stimulation with concanavalin A or lipopolysaccharide. Our results showed that serglycin, unlike hyaluronate, is produced and secreted in a functional (CD44 binding) form by many members of the hematopoietic system including various lymphocyte subsets. Our data suggest that serglycin may serve as a major ligand for CD44 in various events in the lymphohematopoietic system. Serglycin is a family of small proteoglycans with Ser-Gly dipeptide repeats and is modified with various types of glycosaminoglycan side chains. We previously demonstrated that chondroitin sulfate-modified serglycin is a novel ligand for CD44 involved in the adherence and activation of lymphoid cells. In this study, we investigated the production and distribution of CD44 binding serglycins in various hematopoietic cells and characterized their carbohydrate side chains. Immunoprecipitation analysis using CD44-IgG and polyclonal antibody against the serglycin core peptide demonstrated that various serglycin species capable of binding CD44 are produced by a variety of hematopoietic cells including lymphoid cells, myeloid cells, and a few tumor cell lines. Glycosaminoglycans on these serglycins, which are essential for CD44 binding, are composed of chondroitin 4-sulfate or a mixture of chondroitin 4-sulfate and chondroitin 6-sulfate, but no heparin or heparan sulfate side chain was detected. The serglycins are also secreted by normal splenocytes, lymph node lymphocytes, and bone marrow cells, whereas they are secreted in very small amounts by normal thymocytes. Secretion of serglycins is greatly enhanced by mitogenic stimulation with concanavalin A or lipopolysaccharide. Our results showed that serglycin, unlike hyaluronate, is produced and secreted in a functional (CD44 binding) form by many members of the hematopoietic system including various lymphocyte subsets. Our data suggest that serglycin may serve as a major ligand for CD44 in various events in the lymphohematopoietic system. CD44, a cytoskeleton-associated cell-surface glycoprotein, acts as an adhesion molecule and signal transducer in the immune system (1Lesley J. Hyman R. Kincade P.W. Adv. Immunol. 1993; 54: 271-335Crossref PubMed Scopus (1028) Google Scholar, 2Haynes B.F. Telen M.J. Hale L.P. Denning S.M. Immunol. Today. 1989; 10: 423-428Abstract Full Text PDF PubMed Scopus (507) Google Scholar). Previous studies using anti-CD44 monoclonal antibodies showed that this molecule is involved in T cell activation (2Haynes B.F. Telen M.J. Hale L.P. Denning S.M. Immunol. Today. 1989; 10: 423-428Abstract Full Text PDF PubMed Scopus (507) Google Scholar, 3Arch R. Wirth K. Hofmann M. Ponta H. Matzku S. Herrlich P. Zoller M. Science. 1992; 257: 682-685Crossref PubMed Scopus (401) Google Scholar, 4Naujokas M.F. Morin M. Anderson M.S. Peterson M. Miller J. Cell. 1993; 74: 257-268Abstract Full Text PDF PubMed Scopus (202) Google Scholar), tumor metastasis (5Gunthert U. Hofmann M. Rudy W. Reber S. Zoller M. Haussmann I. Matzku S. Wenzel A. Ponta H. Herrlich P. Cell. 1991; 65: 13-24Abstract Full Text PDF PubMed Scopus (1598) Google Scholar,6Herrlich P. Zoller M. Pals S.T. Ponta H. Immunol. Today. 1993; 14: 395-399Abstract Full Text PDF PubMed Scopus (270) Google Scholar), hematopoiesis (7Miyake K. Medina K.L. Hayashi S.-I. Ono S. Hamaoka T. Kincade P. J. Exp. Med. 1990; 171: 477-488Crossref PubMed Scopus (534) Google Scholar, 8Delfino D.V. Patrene K.D. Deleo A.B. Deleo R. Herberman R.B. Boggs S.S. J. Immunol. 1994; 152: 5171-5179PubMed Google Scholar), and lymphocyte homing (9Jalkanen S.T. Bargatze R.F. de los Toyos J. Butcher E.C. J. Cell Biol. 1987; 105: 983-990Crossref PubMed Scopus (479) Google Scholar). It has also been demonstrated that CD44 is a cell-surface receptor for hyaluronate (10Aruffo A. Stamenkovic I. Melnick M. Underhill C.B. Seed B. Cell. 1990; 61: 1303-1313Abstract Full Text PDF PubMed Scopus (2160) Google Scholar), collagen (11Carter W.G. Wayner E.A. J. Biol. Chem. 1988; 263: 4193-4201Abstract Full Text PDF PubMed Google Scholar), fibronectin (12Jalkanen S. Jalkanen M. J. Cell Biol. 1992; 116: 817-825Crossref PubMed Scopus (453) Google Scholar), and chondroitin sulfate-modified class II invariant chain (4Naujokas M.F. Morin M. Anderson M.S. Peterson M. Miller J. Cell. 1993; 74: 257-268Abstract Full Text PDF PubMed Scopus (202) Google Scholar). Recently, we reported that chondroitin sulfate-type serglycin is a novel ligand for CD44 (13Toyama-Sorimachi N. Sorimachi H. Tobita Y. Kitamaura F. Yagita H. Suzuki K. Miyasaka M. J. Biol. Chem. 1995; 270: 7437-7444Abstract Full Text Full Text PDF PubMed Scopus (170) Google Scholar). Serglycin is a secretory granule proteoglycan, and its mRNA is transcribed in hematopoietic lineage cells, yolk sac, and certain tumor cells (14Stevens R.L. Kamada M.M. Serafin W.E. Curr. Top. Microbiol. Immunol. 1988; 140: 93-108Google Scholar). The transcription of the serglycin gene is regulated during tissue development and modulated by activation stimuli such as virus infection (15Stellrecht C.M. Mars W.M. Miwa H. Beran M. Saunders G.F. Differentiation. 1991; 48: 127-135Crossref PubMed Scopus (28) Google Scholar, 16Birkenbach M. Josefsen K. Yalamanchili R. Lenoir G. Kieff E. J. Virol. 1993; 67: 2209-2220Crossref PubMed Google Scholar). Although the function of serglycin remains to be fully determined, it has been suggested that it is involved in myeloid cell differentiation, as well as in cell-mediated cytotoxicity such that it helps packaging and stabilizing cytokines and proteases in secretory granules and transporting them to target sites when secreted extracellularly (14Stevens R.L. Kamada M.M. Serafin W.E. Curr. Top. Microbiol. Immunol. 1988; 140: 93-108Google Scholar,17Masson D. Peters P.J. Geuze H.J. Borst J. Tschopp J. Biochemistry. 1990; 29: 11229-11235Crossref PubMed Scopus (86) Google Scholar, 18Matsumoto R. Sali A. Ghildyal N. Karplus M. Stevens R.L. J. Biol. Chem. 1995; 270: 19524-19531Abstract Full Text Full Text PDF PubMed Scopus (103) Google Scholar, 19Kolset S.O. Mann D.M. Uhlin-Hansen L. Winberg J.-O. Ruoslahti E. J. Leukocyte Biol. 1996; 59: 545-554Crossref PubMed Scopus (66) Google Scholar). We have demonstrated that when the chondroitin sulfate-type serglycin, stored in secretory granules of a mouse T cell line, CTLL2, is secreted, it binds specifically to CD44 (13Toyama-Sorimachi N. Sorimachi H. Tobita Y. Kitamaura F. Yagita H. Suzuki K. Miyasaka M. J. Biol. Chem. 1995; 270: 7437-7444Abstract Full Text Full Text PDF PubMed Scopus (170) Google Scholar). We also showed that the addition of purified serglycin to CTL clones significantly enhances CD3-dependent granzyme release by these clones (13Toyama-Sorimachi N. Sorimachi H. Tobita Y. Kitamaura F. Yagita H. Suzuki K. Miyasaka M. J. Biol. Chem. 1995; 270: 7437-7444Abstract Full Text Full Text PDF PubMed Scopus (170) Google Scholar). Hyaluronate had no effect on the granzyme release, suggesting that the chondroitin sulfate-type serglycin has a unique function in CTL responses (13Toyama-Sorimachi N. Sorimachi H. Tobita Y. Kitamaura F. Yagita H. Suzuki K. Miyasaka M. J. Biol. Chem. 1995; 270: 7437-7444Abstract Full Text Full Text PDF PubMed Scopus (170) Google Scholar). There are certain differences in post-translational carbohydrate modification and degradation of serglycin peptide core in different cell types (14Stevens R.L. Kamada M.M. Serafin W.E. Curr. Top. Microbiol. Immunol. 1988; 140: 93-108Google Scholar). Serglycin carries mainly two types of carbohydrate chains, heparan sulfate or chondroitin sulfate. In human NK cells, the peptide core is thought to be cleaved in the secretory granule at its N and C termini, leaving a glycosaminoglycan attachment region consisting primarily of alternating serine and glycine residues (14Stevens R.L. Kamada M.M. Serafin W.E. Curr. Top. Microbiol. Immunol. 1988; 140: 93-108Google Scholar). In rat LGL tumor cells, serglycin is metabolized by an endoglycosidase to individual chondroitin sulfate A in the secretory granule (14Stevens R.L. Kamada M.M. Serafin W.E. Curr. Top. Microbiol. Immunol. 1988; 140: 93-108Google Scholar). In this regard, it is of note that neither the serglycin core peptide (as shown in this study) nor the modifying chondroitin sulfate alone can bind CD44 (13Toyama-Sorimachi N. Sorimachi H. Tobita Y. Kitamaura F. Yagita H. Suzuki K. Miyasaka M. J. Biol. Chem. 1995; 270: 7437-7444Abstract Full Text Full Text PDF PubMed Scopus (170) Google Scholar). Therefore, it is not clear whether all the serglycins synthesized by hematopoietic cells actually are able to bind CD44. The aim of the present study was to examine the extent of the expression of CD44-binding serglycins in hematopoietic cells and to characterize their chondroitin sulfate side chains. Our results showed that the chondroitin sulfate-type serglycin capable of binding CD44 is secreted by a wide range of hematopoietic cells, including malignant cell lines and normal cells, and that mitogenic stimulation greatly enhances its secretion. We found also that the glycosaminoglycan side chains of the CD44 binding serglycins consist of mainly conventional chondroitin sulfate such as chondroitin 4-sulfate, chondroitin 6-sulfate, or a mixture of both. The results that a variety of blood cells produce the CD44 binding serglycin implies that serglycin may serve as a major ligand for CD44 in the hematopoietic system. Female C57BL/6 (6–8 weeks of age) were purchased from Shizuoka Laboratory Animal Center (Hamamatsu, Japan). Female Japanese White rabbits (1.5–2.0 kg body weight) were purchased from the Shiraishi Laboratory Farm (Tokyo, Japan). All experiments were performed according to the Guidelines for Animal Use and Experimentation as set by our institutions. Mouse cytotoxic T cell clones were kindly provided by Dr. S. Aizawa (Department of Physiology and Pathology, The National Institute of Radiological Science). The culture medium was RPMI 1640 containing 10% fetal calf serum (lot FKB09, Mitsubishi Kasei Co., Tokyo, Japan), 10 mm HEPES, 2 mml-glutamine, 1 mm sodium pyruvate, 10−4m 2-mercaptoethanol, 1% (v/v) 100 × non-essential amino acids (Flow Laboratories, Irvine, CA), 100 units/ml penicillin, and 100 μg/ml of streptomycin. Preparation of CD44-IgG was performed as described previously (10Aruffo A. Stamenkovic I. Melnick M. Underhill C.B. Seed B. Cell. 1990; 61: 1303-1313Abstract Full Text PDF PubMed Scopus (2160) Google Scholar). Control human IgG was purchased from Sigma. Chondroitinase ABC (from Proteus vulgaris, protease-free) and hyaluronidase (fromStreptomyces hyalurolyticus) were purchased from Seikagaku Kogyo (Tokyo). Female Japanese White rabbits were immunized with 125 μg of the synthetic peptide (see Fig. 2 A) suspended in Freund's complete adjuvant and boosted at intervals of 2 weeks with the same amount of the peptide in Freund's incomplete adjuvant. The peptide was derived from a region that lies adjacent to the Ser-Gly repeats and has no homology to any known molecules according to the homology search using EMBLE protein data base, release 27.0. The peptide was synthesized using Peptide Synthesizer model 433A and Fmoc 9N-(9-fluorenyl) methoxycarbonyl) mitogen-activated protein resin (Applied Biosystems Division, Perkin-Elmer). All injections were performed subcutaneously. The rabbits were bled 2 or 3 days after immunization. To obtain antibodies, pSG, specific for the serglycin peptide core, the antiserum was purified on Affi-Gel 10 affinity column where the synthetic peptide was coupled. Purified serglycin was obtained as described previously (13Toyama-Sorimachi N. Sorimachi H. Tobita Y. Kitamaura F. Yagita H. Suzuki K. Miyasaka M. J. Biol. Chem. 1995; 270: 7437-7444Abstract Full Text Full Text PDF PubMed Scopus (170) Google Scholar) and coated on 96-well microtiter plates overnight at 4 °C. Immobilized serglycin was digested with chondroitinase ABC (0.2 units/ml) for 60 min at 37 °C, and then nonspecific sites were blocked with 1% bovine serum albumin in PBS 1The abbreviations used are: PBS, phosphate-buffered saline; PCR, polymerase chain reaction. for 2 h at room temperature. Binding of CD44-IgG (10 μg/ml) or polyclonal anti-serglycin core protein antibody, pSG (10 μg/ml), to each well was examined as described previously (13Toyama-Sorimachi N. Sorimachi H. Tobita Y. Kitamaura F. Yagita H. Suzuki K. Miyasaka M. J. Biol. Chem. 1995; 270: 7437-7444Abstract Full Text Full Text PDF PubMed Scopus (170) Google Scholar). Metabolic labeling with [35S]methionine and [35S]sodium sulfate was performed as described previously (20Toyama-Sorimachi N. Miyasaka M. Int. Immunol. 1994; 6: 655-660Crossref PubMed Scopus Google Scholar). Immunoprecipitation analysis was performed using protein with 10 μg of human pSG, or of were to was using a Co., Japan). The was using was using with The were then used as for in which the and were The was of the the were on were overnight in the of [35S]sodium and serglycin in culture were with with chondroitinase the were to analysis by using as reported previously H. K. J. Biol. Chem. 1995; 270: Full Text Full Text PDF PubMed Scopus Google Scholar). Mouse cell cells were with PBS, and to × in and In the of the cell was each well of a which purified serglycin μg/ml) was the cell was on a at for min at room temperature. was by In the antibody μg/ml of a anti-CD44 antibody (7Miyake K. Medina K.L. Hayashi S.-I. Ono S. Hamaoka T. Kincade P. J. Exp. Med. 1990; 171: 477-488Crossref PubMed Scopus (534) Google Scholar) was to the cell to the of 96-well microtiter were coated with IgG μg/ml) at 4 with PBS, purified CD44-IgG or human IgG was to the for 60 by the addition of various of purified we examined cell adhesion to these using cells with a as described previously N. K. Miyasaka M. J. Immunol. 1993; PubMed Scopus Google Scholar). The of serglycin was examined by analysis using CD44 on culture from various hematopoietic cell lines. The cell lines and a of CTL has in the to chondroitin sulfate-modified serglycin as a novel ligand for CD44 in a mouse T cell (20Toyama-Sorimachi N. Miyasaka M. Int. Immunol. 1994; 6: 655-660Crossref PubMed Scopus Google Scholar). shown in Fig. to in were with CD44-IgG from culture of and CTL clones but not from or molecules were not with human IgG or such as N. Miyasaka M. Int. Immunol. 1994; 6: 655-660Crossref PubMed Scopus Google Scholar). The molecules as a that by chondroitinase ABC not suggesting that the are modified with chondroitin sulfate that can bind CD44. molecules were not suggesting that chondroitin sulfate-type proteoglycans the major CD44 binding in these cell lines. To whether these CD44 binding molecules are to chondroitin sulfate-type serglycin, we a polyclonal antibody against a of the peptide of the mouse serglycin peptide core The of the polyclonal anti-serglycin antibody was by affinity purified pSG not mouse serglycin purified from mouse T cell 2 to which binding of was 2 with chondroitinase in a binding of pSG to serglycin 2 but binding 2 suggest that pSG a protein by glycosaminoglycan chains, whereas a glycosaminoglycan on In of this pSG the serglycin core protein derived from whereas serum not 2 pSG, we then investigated whether the core protein obtained from various hematopoietic cell lines that of To this proteoglycans with CD44-IgG were with chondroitinase and their with pSG was from peptide core from all the examined cell lines with pSG and showed from to to the of the serglycin core The differences in be to differences in post-translational modification with glycosaminoglycan chains and to differences in glycosaminoglycan region to the core protein which is from chondroitinase To characterize on serglycin involved in CD44 were obtained from the serglycin by chondroitinase ABC and to on a column with using of The of the from cell to but the of on serglycin were of chondroitin chondroitin Serglycin synthesized by and was modified with chondroitin 4-sulfate, whereas serglycin from was modified mainly by chondroitin 4-sulfate and chondroitin Serglycin from was modified with types of chondroitin with chondroitin the to heparan hyaluronate, or any unique were not results suggest that the CD44-binding serglycins are modified by conventional chondroitin and that the binding of CD44 to serglycin is of the of the modifying chondroitin sulfate In the we examined whether normal hematopoietic cells produce serglycins capable of binding CD44. this of lymph node cells, splenocytes, and bone marrow cells were in the of sodium and analysis was performed on their culture using shown in of were in the culture of and lymph node cells, whereas a was in bone marrow cells. of lymphoid cells with concanavalin A or the of serglycin showed in pSG with core protein obtained by these molecules with chondroitinase ABC not that these molecules chondroitin sulfate-modified of serglycin was in of the or of transcription of the serglycin gene was by To the functional of the serglycin, we examined the effect of purified serglycin to various hematopoietic cell lines. of serglycin used in this of experiments was shown in the (13Toyama-Sorimachi N. Sorimachi H. Tobita Y. Kitamaura F. Yagita H. Suzuki K. Miyasaka M. J. Biol. Chem. 1995; 270: 7437-7444Abstract Full Text Full Text PDF PubMed Scopus (170) Google Scholar). cell lines such as and all CD44, a of a few to of cells which not normal The was by anti-CD44 monoclonal antibody, suggesting that is for the and that serglycin acts as a CD44 on the of different cells. The cell was in the of and that neither nor are involved in this To the of cell we performed the cell adhesion using CD44 and purified serglycin was to where had been cells The was specifically by anti-CD44 In cells to bind when or human IgG alone was to in the of that serglycin as a cell-surface CD44 and to the that serglycin is involved in by CD44 We reported previously that chondroitin sulfate-type serglycin is a novel ligand for CD44 and that the chondroitin sulfate side chain an in by CD44 (13Toyama-Sorimachi N. Sorimachi H. Tobita Y. Kitamaura F. Yagita H. Suzuki K. Miyasaka M. J. Biol. Chem. 1995; 270: 7437-7444Abstract Full Text Full Text PDF PubMed Scopus (170) Google Scholar). The serglycin gene is transcribed in including and (15Stellrecht C.M. Mars W.M. Miwa H. Beran M. Saunders G.F. Differentiation. 1991; 48: 127-135Crossref PubMed Scopus (28) Google Scholar). modifying the serglycin peptide core are in their extent of or of (14Stevens R.L. Kamada M.M. Serafin W.E. Curr. Top. Microbiol. Immunol. 1988; 140: 93-108Google Scholar, R.L. U. S. A. 1988; PubMed Scopus Google Scholar). it is not clear whether these cells actually produce serglycins that can bind CD44. In the present study, we for the that a variety of hematopoietic cells produce chondroitin sulfate-type serglycin capable of binding CD44. analysis showed that the modifying the CD44 binding serglycin from cell to and consist of mainly conventional chondroitin such as chondroitin 4-sulfate, chondroitin 6-sulfate, or a mixture of both. that the binding of serglycin to CD44 is of its chondroitin sulfate Although neither heparin nor heparan sulfate nor any unique was from the CD44 binding serglycins, it remains to be serglycins, such as produced by tissue cells (14Stevens R.L. Kamada M.M. Serafin W.E. Curr. Top. Microbiol. Immunol. 1988; 140: 93-108Google Scholar), can actually bind CD44. A of production of CD44 binding serglycin was in bone marrow cells. In this it is that the expression of the serglycin gene very in hematopoiesis (15Stellrecht C.M. Mars W.M. Miwa H. Beran M. Saunders G.F. Differentiation. 1991; 48: 127-135Crossref PubMed Scopus (28) Google Scholar) and that CD44 is involved in bone marrow hematopoiesis (7Miyake K. Medina K.L. Hayashi S.-I. Ono S. Hamaoka T. Kincade P. J. Exp. Med. 1990; 171: 477-488Crossref PubMed Scopus (534) Google Scholar, 8Delfino D.V. Patrene K.D. Deleo A.B. Deleo R. Herberman R.B. Boggs S.S. J. Immunol. 1994; 152: 5171-5179PubMed Google Scholar). the of to of in (7Miyake K. Medina K.L. Hayashi S.-I. Ono S. Hamaoka T. Kincade P. J. Exp. Med. 1990; 171: 477-488Crossref PubMed Scopus (534) Google Scholar), it is thought that the with hyaluronate is for CD44 in the of that serglycin is by hematopoietic cells and that it binds to the hyaluronate binding or its on the CD44 core protein (13Toyama-Sorimachi N. Sorimachi H. Tobita Y. Kitamaura F. Yagita H. Suzuki K. Miyasaka M. J. Biol. Chem. 1995; 270: 7437-7444Abstract Full Text Full Text PDF PubMed Scopus (170) Google Scholar), it be to in studies of the at all to the of hematopoietic cells in the bone In the with CD44, serglycin may also be for the binding of hematopoietic by their and them to hematopoietic cells. studies have the of of by proteoglycans in the of cell and adhesion S.O. Mann D.M. Uhlin-Hansen L. Winberg J.-O. Ruoslahti E. J. Leukocyte Biol. 1996; 59: 545-554Crossref PubMed Scopus (66) Google Scholar, D. L. Cell Immunol. 1989; Scopus Google Scholar, Y. S. Curr. Top. Microbiol. Immunol. 1993; Google Scholar, A. M. P. D.M. Cell. 1991; Full Text PDF PubMed Scopus Google Scholar). Our results also showed that normal lymph node cells and also produce the CD44 binding serglycin, which is enhanced by stimulation with concanavalin A or lipopolysaccharide. and that T produce chondroitin sulfate proteoglycans that are secreted the M. 1990; PubMed Scopus Google Scholar, S.O. 1990; Google Scholar). Our that not produce the CD44 binding serglycin but the serglycin gene whereas and lymph node cells actually produce the CD44 binding serglycin that the production of serglycin with a CD44 binding may with T cell Although the function of serglycin in the T cell lineage remains to be fully the results of our study that serglycin acts on T cells and the release of their granzyme (13Toyama-Sorimachi N. Sorimachi H. Tobita Y. Kitamaura F. Yagita H. Suzuki K. Miyasaka M. J. Biol. Chem. 1995; 270: 7437-7444Abstract Full Text Full Text PDF PubMed Scopus (170) Google Scholar). to the receptor T CD44 but not bind hyaluronate they are R. J. R. 1991; PubMed Scopus Google Scholar, J. K. A. Hyman R. Kincade P. J. Exp. Med. 1992; PubMed Scopus Google Scholar). is also the with binding to serglycin (13Toyama-Sorimachi N. Sorimachi H. Tobita Y. Kitamaura F. Yagita H. Suzuki K. Miyasaka M. J. Biol. Chem. 1995; 270: 7437-7444Abstract Full Text Full Text PDF PubMed Scopus (170) Google Scholar). hyaluronate or serglycin may be found in the hematopoietic with CD44 when activation is which may for be an a cell-surface receptor and of the lymphohematopoietic system. the expression of serglycin in the hematopoietic cell which is different from the expression of described for CD44 such as hyaluronate, and may also the of CD44 Cell and binding experiments that serglycin can as well as cell by CD44 molecules on cells. Although it has been shown previously that stimulation of CD44 cell adhesion by molecules certain N. K. Miyasaka M. J. Immunol. 1993; PubMed Scopus Google Scholar, G. Y. de M. Pals S.T. J. Immunol. 1990; Google Scholar), cell by the addition of serglycin is not by adhesion molecules such as or was not by of such as Our that the binding is in the of antibodies against or also the of and M. it is of whether cells in lymph produce serglycin, CD44 was as lymphocyte homing receptor of lymphoid (9Jalkanen S.T. Bargatze R.F. de los Toyos J. Butcher E.C. J. Cell Biol. 1987; 105: 983-990Crossref PubMed Scopus (479) Google Scholar). has also been that a for CD44 on cells is not hyaluronate but an as M. K. Kincade P.W. E. Butcher E.C. Underhill J. Cell Biol. 1990; PubMed Scopus Google Scholar). experiments in our using polyclonal anti-serglycin core peptide antibody that serglycin is not present in in mouse lymph at at Therefore, it is not clear at present that serglycin any in lymphocyte The in and function of the in various cell types remains to be our results the production of serglycin serve as an for of the function of serglycin and CD44. that the CD44-binding serglycin is in hematopoietic cells and that its expression is to the hematopoietic tissue normal (14Stevens R.L. Kamada M.M. Serafin W.E. Curr. Top. Microbiol. Immunol. 1988; 140: 93-108Google Scholar), it is to suggest that serglycin may serve as a major ligand for CD44 in the hematopoietic system. We Dr. Sorimachi for We also and for