Express Complement Receptors Research Articles

Follicular dendritic cell tumor presenting in the lung: A case report

An example of extranodal follicular dendritic cell sarcoma (FDCS) presenting in the lung, a heretofore unreported site, is described. Macroscopically, a 9.5-cm, tan-white, dominant mass and multiple smaller parenchymal and pleural nodules were identified. Microscopically, the tumor was composed of spindled cells with uniform cytologic features arranged in short, intersecting fascicles and intermixed small lymphocytes and plasma cells. One of 4 peribronchial and hilar lymph nodes evaluated microscopically was focally involved by the process. Immunohistochemically, the neoplastic spindled cells expressed complement receptors CD21 and CD35 and low-affinity nerve growth factor receptor but did not express keratin (AE1/AE3 and CAM5.2), CD45 (leukocyte common antigen), CD20 (L26), S-100 protein, muscle-specific actin, or gp100 protein (HMB45). Ultrastructurally, the tumor cells have complex interdigitating cell surface processes and desmosomes. Epstein-Barr virus (EBV) was not detected in the tumor cells by in situ hybridization for EBV-encoded RNA or by polymerase chain reaction for viral DNA. FDCS should be considered in the differential diagnosis of any spindled-cell tumor with interspersed chronic inflammatory cells occurring in the lung. An immunohistochemical panel, including anti-CD21 and -CD35, can assist in its diagnosis, especially with small bronchial biopsy specimens. HUM PATHOL 32:745-749. Copyright © 2001 by W.B. Saunders Company

Systemic complement depletion reduces inflammation and demyelination in adoptive transfer experimental allergic neuritis.

The effect of systemic complement depletion by cobra venom factor (CVF) was evaluated in adoptive transfer experimental allergic neuritis (AT-EAN). Spleen cells of rats immunized with a neuritogenic peptide SP26 were injected into naive rats. On days 3 and 6 after cell transfer AT-EAN rats were treated with CVF or saline intraperitoneally. AT-EAN rats treated with CVF had significantly lower scores for histological inflammation (0.25 +/- 0.25 vs 1.9 +/- 0.4, mean +/- SEM, P < 0.03) and demyelination (0.13 +/- 0.13 vs 1.6 +/- 1.4, P < 0.02) than saline-treated AT-EAN rats. Immunocytochemistry of lumbosacral nerve roots showed significantly less ED1-positive macrophages (0.5 +/- 0.3 vs 1.6 +/- 0.6, P < 0.04) and CD11bc-positive (expressing complement receptor 3 or CR3) inflammatory cells (0.6 +/- 0.4 vs 1.7 +/- 0.5, P < 0.03). Our data suggest that complement plays a crucial role in inflammatory demyelination since systemic complement depletion significantly reduces recruitment of macrophages into the nerve and subsequent macrophage-mediated demyelination.

Phosphorylation of complement component C3 after synthesis in U937 cells by a putative protein kinase, casein kinase 2, which is regulated by CD11b: evidence that membrane-bound proteases preferentially cleave phosphorylated C3.

It was our aim in this study to investigate the possibility that the third component of complement (C3) is phosphorylated during synthesis and secretion in U937 cells. Labelling of U937 cells with [32P]Pi, followed by immunoprecipitation of C3 from cell lysates and culture supernatants at different time points, showed that C3 was phosphorylated intracellularly immediately before release into the medium, which initiated cleavage of the protein into an iC3b-like fragment. Stimulation of CD11b/CD18 increased phosphorylation 7-fold, from a basal level of 2%. The phosphorylation sites in C3 did not resemble those described previously for casein kinase (CK) 1, cAMP-dependent protein kinase A or calcium- and phospholipid-dependent protein kinase C. Instead, protein kinase CK2 was suggested inasmuch as: (1) CK2 was detected both on the cell surface and on shed microparticles; (2) phosphorylation of purified C3 by microparticles was abolished by a monoclonal antibody, anti-CK2; (3) the [32P]Pi tag of both phosphorylated C3 (secreted from U937 cells) and of microparticle-phosphorylated C3, which was cleaved either by membrane proteases or by leucocyte elastase, was found in a 40 and a 70 kDa polypeptide; (4) both secreted C3 and C3 phosphorylated in vitro were much more susceptible to cleavage by proteases. Generation of C3 fragments provides a means by which U937 cells can stimulate nearby cells which are expressing complement receptors. The present study demonstrates that the cleavage of C3 is controlled by an intracellular phosphorylation event regulated by CD11b/CD18.

Soluble complement receptor 1 (sCR1) is not as effective as cobra venom factor in the treatment of experimental allergic neuritis

To further investigate the role of complement activation in Experimental Allergic Neuritis (EAN), the effect of systemic complement blockade by soluble CR1 (sCR1) was compared to complement depletion by Cobra Venom Factor (CVF) in EAN rats immunized with bovine peripheral nerve myelin. EAN rats treated with CVF (n = 10) had significantly reduced clinical scores compared to rats treated with sCR1 (n = 9) or saline (n = 10) (score: sCR1 0.66 ± 0.7; CVF 0; saline 0.6 ± 0.8; mean ± SD). CVF treatment more effectively decreased inflammation and demyelination compared to sCR1 treatment which had only a partial effect (inflammation: sCR1 1.8 ± 1.4; CVF 0.3 ± 0.7; saline 1.9 ± 1.2; demyelination; sCR1 1.3 ± 1; CVF 0.1 ± 0.6; saline 1.7 ± 1.2). In lumbosacral nerve roots significantly less infiltrating ED1 positive macrophages and CD11bc (expressing complement receptor 3 or CR3) positive inflammatory cells were present in CVF treated EAN rats while there was a limited decrease in inflammation in the sCR1 treated animals compared to the saline treated rats (ED1: sCR1 1.4 ± 1.2; CVF 0.5 ± 0.6; saline 1.7 ± 1.2; CD11bc: sCR1 1.9 ± 1.2; CVF 0.9 ± 1; saline 2.1 ± 1.2). Our findings suggest that complement depletion by CVF is more effective than complement blockade by sCR1 in reducing the severity of inflammatory peripheral nerve demyelination.

The role of complement receptor type 1 (CR1, CD35) in determining the cellular distribution of opsonized immune complexes between whole blood cells: kinetic analysis of the buffering capacity of erythrocytes.

Erythrocytes (E) express complement receptor, type 1 (CR1, CD35), by which they bind opsonized immune complexes (IC) in competition with leucocytes expressing higher numbers of CR1 as well as other complement- and Fc-receptors. This may prevent inappropriate activation of phagocytic cells. We examined the distribution on whole blood cells of preformed tetanus toxoid (TT)/human anti-TT IC, opsonized in situ in 80% autologous serum. Binding to E occurred rapidly and reflected the kinetics of C3-fragment incorporation into the IC. Among eight donors, expressing 180-361 CR1 per E. > 90% of the cell-bound IC were associated with E from 1 to 5 min of incubation, decreasing to 12 +/- 13% after 40 min. Upon comparison of the IC-binding to leucocytes in whole blood with that of isolated leucocytes we found that E, despite their extensive early complex uptake, only reduced the IC-deposition on polymorphonuclear leucocytes (PMN) by 61 +/- 26% after 30 seconds of incubation and 47 +/- 14% after 5 min. During the subsequent 10 min, this buffering capacity of E was essentially abolished E restricted the initial IC-binding to B cells by 73 +/- 19%, but from 3 min of incubation the presence of E promoted, in a CR1-dependent manner, a progressive uptake via CR2 by the B cells. CR1 was the dominant receptor in the early IC-uptake by B cells as well as PMN and monocytes, since CR1-blockade inhibited the initial IC-uptake by these populations in a preparation of isolated leucocytes suspended in serum by > or = 84% after 30 seconds of incubation. We conclude, that E exert a substantial buffering effect on the IC-deposition on PMN, monocytes and B cells, while CR1 is the dominant receptor in the uptake by these cells. However, this effect is short-lived and less than expected from the proportion of IC bound to E. Moreover, E are efficient processors of IC-attached C3b/iC3b fragments to C3dg as indicated by a pronounced enhancement by E of IC-uptake via CR2 on B cells. We propose that this mechanism may play a role in preventing phagocyte activation via CR3.

Complement biosynthesis in the central nervous system.

Complement is an important effector arm of the human immune response. Binding of proteolytic fragments derived from activation of complement by specific receptors leads to responses as diverse as inflammation, opsonization, and B-cell activation. The importance of characterizing the expression and regulation of complement in the CNS is highlighted by growing evidence that complement plays a significant role in the pathogenesis of a variety of neurological diseases, such as multiple sclerosis and Alzheimer's disease. In vitro studies have demonstrated that astrocytes, the predominant glial cell type in the brain, are capable of expressing or producing a majority of the components of the complement system. Expression of many complement proteins synthesized by astrocytes is regulated by both pro- and anti-inflammatory cytokines, many of which are also produced by several cell types in the CNS. In addition to astrocytes, ependymal cells, endothelial cells, microglia, and neurons have recently been shown to synthesize various complement proteins or express complement receptors on their cell surfaces. Together, these studies demonstrate that several cell types throughout the brain have the potential to express complement and, in many cases, increase expression in response to mediators of the acute phase response. These studies suggest that complement may play a greater role in CNS immune responses than previously thought, and pave the way for better understanding of the dynamics of complement expression and regulation in vivo. Such understanding may lead to therapeutic manipulation of complement host defense functions in a variety of inflammatory and degenerative diseases in the CNS.

Erythrocyte Complement Receptors

Primate erythrocytes express complement receptors (E-CR), which can extrinsically bind C3b and Cb4. This interaction allows primate erythrocytes to bind complement opsonized particles and immune complexes, a phenomenon historically referred to as immune adherence. The binding of C3b and C4b by E-CR also leads to inhibition of complement activation. The human E-Cr is the complement activation. The human E-CR is the complement receptor type 1, or CR1, which is codominantly expressed as four polymorphic allotypes, ranging in size from 190,000 to 280,000 M(r). Non-human primate E-CR are similar to CR1 in function and antigenicity and are likely homologous to CR1 in structure; however, they are one third to one half the size of CR1. The physiological role of E-CR, determined from studies in monkeys and humans, is to allow erythrocytes to perform as inert shuttles for circulating immune complexes (IC), safely directing IC to the organs of the monocyte phagocytic system, thus preventing indiscriminate IC deposition in vulnerable tissue. In IC-mediated diseases, such as systemic lupus erythematosus (SLE), detectable erythrocyte CR1 levels are reduced, an abnormality that in part is acquired during disease activity. The loss of erythrocyte CR1 may be an important pathogenic factor in the development and severity of SLE.

A biologic basis for altered host defenses in surgically infected abscesses.

This study determines whether there are any differences in several immunologic parameters in circulating peripheral blood leukocytes, serum, and plasma compared with pus leukocytes, and supernatant of various types of abscess. Although there have been reports of high lysozyme levels and low complement levels within pus, there has been no systemic comparison of concentrations of these substances and others within pus compared with those within peripheral blood. Peripheral blood and abscess pus were collected from 31 patients with abscesses and percent and mean channel of monocytes expressing complement receptor and major histocompatibility antigen HLA-DR, the percent and mean channel of polymorphonuclear leukocytes (PMN) expressing complement receptor, lysozyme level, and levels of total hemolytic complement, iC3b, C5b-9, and immunoglobulins were measured within both pus and peripheral blood. Percent of monocytes expressing HLA-DR and percent of monocytes and PMN expressing complement receptor, total hemolytic complement, and IgM were reduced within pus compared with peripheral blood, whereas the mean channel of monocytes expressing HLA-DR and the mean channel of PMNs expressing CR3, C5b-9, and lysozyme were increased in pus. There are marked differences in immunologic parameters measured within pus of abscesses versus that seen in peripheral blood.

CD11b is a calcium-dependent epitope in human neutrophils

Human neutrophils expressing complement receptor 3 (CR3) were treated with various concentrations (0.04-10 mM) of Ca2+/Mg(2+)-chelating agent EDTA and the expression of CD11b, the CR3 alpha chain antigenic epitope, was examined using monoclonal antibodies and flow cytometry. EDTA caused a dose-dependent decrease in the reactivity of two anti-CD11b monoclonal antibodies, Leu15 and IOM1. The reduced expression of CD11b in EDTA-treated cells was partly restored by the addition of Ca2+ ions whereas the addition of Mg2+ ions had no effect on CD11b level. The expression of the CR3 beta chain epitope, CD18, was markedly decreased only by 10 mM EDTA. These results suggest that the CD11b epitope may be associated with the Ca(2+)-binding domains of CR3 alpha chain and its recognition by antibodies depends on the presence of bound Ca2+.

Ph 1-positive CML-derived myeloid-monocytoid precursor cell line producing substance(s) that stimulates normal CFU-C

A new Ph 1-chromosome positive cell line, KOPM-28, was established from a patient with chronic myelogenous leukemia (CML) in blast crisis. KOPM-28 cells were phenotypically immature: without azurophilic granules; negative for myeloperoxidase and positive for specific and nonspecific esterases. The nonspecific esterase reaction was intensified by TPA, and retinoic acid reinforced the specific esterase reaction without inducing morphological changes. KOPM-28 cells were not phagocytic. The cells expressed complement receptors, myeloid-monocytoid antigens, an Ia-like antigen and T4 antigen. CALLA, T-lymphocyte specific antigens, B-lymphocyte related antigen and platelet-megakaryocyte-megakaryoblast specific antigen were not detected. KOPM-28 cells formed colonies in semi-solid medium; this ability was augmented by GM-CSA. The addition of culture medium conditioned by KOPM-28 cells to normal bone marrow cells resulted in the increase of the CFU-C colonies. These findings indicate that KOPM-28 cells have features of myeloid and monocytoid precursor cells and that they are producing substance(s) which stimulates normal CFU-C.

Complement receptor expression of primates and non-primates detected by the rosette formation technique

The expression of complement receptors were studied on erythrocytes and platelets from 14 non-human primates and 3 non-primate species by rosette formation. It was found that the reactivity of erythrocytes with the cell bound complement is deeply dependent on which species are used as the complement source. The erythrocytes from Prosimian do not react with any kind of complement, while their platelets react with many kinds of complement. New World monkey erythrocytes do not react with indicator cells binding complements from guinea pig or man, while some of them react with indicators binding complements from non-human primate species. Contrarily Old World monkey erythrocytes react with complements from guinea pig, man and non-human primate. Hominoidea erythrocytes reacted with all the complements tested. Rabbit expresses C3 receptors on their erythrocytes for rabbit C3 and on their platelets for rabbit, guinea pig or mouse C3. Guinea pig expresses receptors on their erythrocytes for guinea pig and mouse C3, and on their platelets for guinea pig, mouse, rabbit and human C3. It becomes clear that not all of erythrocytes from primate and platelets from non-primate always express complement receptors as has been stated in the text books.

Human dendritic cells. Enrichment and characterization from peripheral blood.

Previous studies demonstrated that lymphoid tissues of mice and rats contain small numbers (less than 1 percent of nucleated cells) of dendritic cells (DC) with special cytologic, surface, and functional properties. We show here that similar DC represent 0.1-0.5 percent of human peripheral blood mononuclear cells. DC can be enriched to 20-60 percent purity by a multistep procedure analogous to that used in mice. Adherent peripheral blood mononuclear cells are cultured overnight, and the released cells are depleted of monocytes and B cells by readherence to plastic, rosetting with erythrocytes coated with anti-human IgG, and centrifugation in dense albumin columns. Enriched DC have similar cytologic features to rodent DC by light and electron microscopy. DC express HLA, and HLA-DR and the leukocyte-common antigens. They lack phagocytic capacity, receptors for antibody-coated and neuraminidase-treated erythrocytes, surface and intracellular Ig, esterase, peroxidase, and azurophilic granules. DC do not react with several monoclonal antibodies directed to phagocytes (OKM 1, "mac-1," 63D3, and 61D3) and T cells (OKT 3, 6, 8). Unlike the mouse, human DC express complement receptors. When maintained in culture for 4 d, human DC did not give rise to either B cells or monocytes. Therefore, DC identified by cytologic criteria are distinct from other leukocytes. Enriched populations of DC have been compared to fractions enriched in monocytes, B cells, and T cells in three functional assays: stimulation of the primary allogeneic mixed leukocyte reaction, stimulation of the primary syngeneic MLR, and accessory function for the proliferation of periodate- modified T cells. In each case, the DC fraction was 10-fold or more active than other cell fractions. We conclude that DC circulate in man, and represent the principal cell type required for the initiation of several immune responses.

Differentiation between benign and malignant human lymph nodes by means of immunologic markers

A surface-marker assay combining immunofluorescence with anti-human immunoglobulin or anti-human brain serum (AHBS) and the formation of rosettes with untreated (E), antibody-sensitized (EA) and complement-coated (EAC) sheep erythrocytes was used to study mononuclear cell suspensions of human lymph nodes. The frequency of cells expressing more than one marker was increased in lymphoma nodes as compared to normal and hyperplastic nodes. The cells which simultaneously expressed complement receptors, surface immunoglobulin and the marker identified by AHBS represented the most prominent and characteristic subpopulation identified in neoplastic nodes. Distributions of cells with double and triple markers were studied by combining immunofluorescence with rosetting on frozen tissue sections. The multiple-marker cells had distributions that were characteristic in different human lymphomas. Benign and malignant human nodes could be distinguished on the basis of frequency and distribution of mononuclear cell populations carrying distinctive combinations of T- and B-cell surface markers.

Lymph node plasmacytoma in a child: Clinical and immunological findings with special reference to S-Ig and complement receptor subtypes

A ten year-old girl presented with increased susceptibility to infection, massive enlargement of the cervical lymph nodes, a high erythrocyte sedimentation rate and an extremely high serum IgA (peak level 66 g/l). The diagnosis of plasmacytoma was confirmed by the identification of a monoclonal immunoglobulin (IgAk) in the serum and in the plasma cells present in a cervical lymph node biopsy. Her disturbed blood coagulation and thrombelastogram, serum hyperviscosity, cryoglobulinemia, hyponatremia and constantly positive test for rheumatoid factor without evidence of rheumatic disease were attributed to the effects of the myeloma proteins. Other signs often associated with plasmacytoma (bone pain, osteolytic lesions, anemia, bone marrow failure or infiltration) were absent indicating that the plasmacytoma originated in a lymph node, which is unusual. This case is the second well-documented childhood plasmacytoma to be reported. With combined melphalan and prednisone therapy, the greatly enlarged lymph nodes regressed in size and the plasma IgA concentration fell to normal. Immunological investigations revealed a considerable reduction of blood T cells, and abnormal skin tests at the time of diagnosis indicated a disturbance of cellular immunity. There were also abnormalities in the B-cell system. The blood B lymphocytes were found to carry only complement receptors for C3b and mainly for IgA, whereas in normal individuals blood B cells bear complement receptors for both C3b and C3d and mainly surface Ig of the IgM class. In the lymph node biopsy, there were many primary follicles expressing complement receptors for both C3b and C3d among the dense plasma cell infiltrates, but germinal centers, which mainly serve to renew B cells, were completely absent. In conjunction with data from the literature, we concluded 1) that the production of normal B lymphocytes is blocked, probably due to a secondary T cell deficiency, and 2) that the majority of the residual blood and bone marrow B cells and the plasmacytoma cells are parts of the same neoplastic cell clone.

Immunofluorescent Method for Positive Identification of Null-Cell Type Acute Lymphocytic Leukemias: Use of Heterologous Antiserum

AbstractAcute lymphoblastic leukemia (ALL) patients could be subclassified into two groups depending on whether or not their leukemia cells expressed a B-lymphocyte antigen. The antigen was detected by an indirect immunofluorescence test using rabbit antisera. In the positive group, consisting of 26 of 32 patients, the leukemia cells were of the “null”-cell type, i.e., they did not appear to express currently recognized T- and B-cell markers. Absorption studies indicated that the positive null-cell group expressed a common antigen which was not expressed on the negative group. Of the 6 negative cases, 5 expressed complement receptors and 3 expressed T-cell markers. The negative group was also characterized by high white cell counts and the presence of a mediastinal mass.

Immunofluorescent method for positive identification of null-cell type acute lymphocytic leukemias: use of heterologous antiserum

Acute lymphoblastic leukemia (ALL) patients could be subclassified into two groups depending on whether or not their leukemia cells expressed a B-lymphocyte antigen. The antigen was detected by an indirect immunofluorescence test using rabbit antisera. In the positive group, consisting of 26 of 32 patients, the leukemia cells were of the “null”- cell type, i.e., they did not appear to express currently recognized T- and -b-cell markers. Absroption studies indicated that the positive null-cell group expressed a common antigen which was not expressed on the negative group. Of the 6 negative cases,, 5 expressed complement receptors and 3 expressed T-cell markers. The negative group was also characterized by high white cell counts and the pressence of a mediastinal mass.

Human B cell line deficient in the expression of B cell-specific glycoproteins (GP 27,35).

A human B lymphoid cell line, P3HR-1, expresses only low levels of the 27 000 and 35 000 mol.wt. B cell-specific glycoproteins (GP 27,35). Indirect antibody-binding and quantitative absorption tests with a xenoantiserum against the antigens showed that P3HR-1 cells have on their surface about 1% of the amount found on other human B lymphoblastoid cell lines. The deficit of the glycoproteins on the surface of P3HR-1 cells could be accounted for by a reduced rate of synthesis in these cells. A simple relationship between the reduced expression of GP 27,35 on P3HR-1 cells and their inability to bind Epstein-Barr virus (EBV) or express complement receptors was excluded because other B lymphoid cells which expressed neither virus-binding sites nor complement receptor had normal amounts of GP 27,35 on their surface. However, antibodies against GP 27,35 could block the absorption of EBV by EBV receptor-positive B cells.

Induction of human granulocyte differentiation in vitro by ubiquitin and thymopoietin

Human bone marrow cells were separated according to density by centrifugation on Ficoll-Hypaque gradients and then according to size by velocity sedimentation. This procedure resulted in fractions enriched for immature granulocytes, mature granulocytes, and lymphocytes. Cells in these fractions were analyzed for their expression of certain surface and functional differentiation markers and for their ability to respond to thymopoietin and ubiquitin with the expression of additional differentiation markers. A higher percentage of band form and segmented granulocytes than of more immature granulocytes expressed complement receptors on their surfaces. Thymopoietin and ubiquitin induced a significant percentage of the cells in the immature granulocyte fraction to express this marker. These data suggested that the complement receptor may be viewed as a differentiation marker on human granulocytes, the expression of which can be induced in vitro by thymopoietin and ubiquitin. Furthermore, fractions containing predominantly band form granulocytes were induced by ubiquitin (but not thymopoietin) to develop the capacity to respond to chemotactic agents, and cell fractions containing predominantly myelocytes and metamyelocytes were induced by thymopoietin and ubiquitin to develop the capacity to phagocytose latex particles. These findings indicated that thymopoietin and ubiquitin, two agents known to induce a number of stages of human and mouse lymphocyte differentiation, are also capable of inducing some stages of human granulocyte differentiation in vitro.

Induction of Human Granulocyte Differentiation In Vitro by Ubiquitin and Thymopoietin

Human bone marrow cells were separated according to density by centrifugation on Ficoll-Hypaque gradients and then according to size by velocity sedimentation. This procedure resulted in fractions enriched for immature granulocytes, mature granulocytes, and lymphocytes. Cells in these fractions were analyzed for their expression of certain surface and functional differentiation markers and for their ability to respond to thymopoietin and ubiquitin with the expression of additional differentiation markers. A higher percentage of band form and segmented granulocytes than of more immature granulocytes expressed complement receptors on their surfaces. Thymopoietin and ubiquitin induced a significant percentage of the cells in the immature granulocyte fraction to express this marker. These data suggested that the complement receptor may be viewed as a differentiation marker on human granulocytes, the expression of which can be induced in vitro by thymopoietin and ubiquitin. Furthermore, fractions containing predominantly band form granulocytes were induced by ubiquitin (but not thymopoietin) to develop the capacity to respond to chemotactic agents, and cell fractions containing predominantly myelocytes and metamyelocytes were induced by thymopoietin and ubiquitin to develop the capacity to phagocytose latex particles. These findings indicated that thymopoietin and ubiquitin, two agents known to induce a number of stages of human and mouse lymphocyte differentiation, are also capable of inducing some stages of human granulocyte differentiation in vitro.