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R P Kimberly

Publications and source records attributed to R P Kimberly.

At least 19 recordsLinked to original sources
PubMed1992

Receptor specific probes for the study of Fc gamma receptor specific function.

Human leukocytes express three distinct families of receptors for the Fc region of IgG (Fc gamma R). We have prepared erythrocytes (E) coated with monoclonal anti-Fc gamma R antibodies for the study of receptor specific phagocytosis using biotin and streptavidin. In this technique, both the E and the monoclonal antibody (mAb) are biotinylated and coupling of the mAb to the E occurs through the use of streptavidin. The same biotin/streptavidin principle was used to prepare E coated with human IgG. Using this technique, receptor specific probes or probes coated with natural ligand (IgG) can be prepared rapidly with the use of small amounts of mAb or IgG. Finally, we have used these receptor specific probes to demonstrate that all three families of Fc gamma R (Fc gamma RI, Fc gamma RII and Fc gamma RIII) expressed on human monocytes and human macrophages are phagocytic receptors.

Antibodies, Monoclonal↗
PubMed1992

Functional characterization of non-human primate erythrocyte immune adherence receptors: implications for the uptake of immune complexes by the cells of the mononuclear phagocytic system.

Erythrocytes from primates express an immune adherence (IA) receptor that binds complement-opsonized immune complexes (IC) both in vivo and in vitro. We have analyzed the immunochemical and functional properties of the IA receptor from erythrocytes from species that have been used for in vivo IC clearance studies and have compared these properties to the human IA receptor (which is called complement receptor type 1, CR1). Erythrocytes from all species (chimpanzee, baboon, rhesus and cynomolgus monkey) bind antibody/double-stranded DNA IC when opsonized with autologous complement. However, IC which are bound to chimpanzee erythrocytes are not released upon addition of chimpanzee serum (which contains factor I activity), while IC bound to baboon erythrocytes and human erythrocytes are released upon addition of autologous serum. Anti-human CR1 monoclonal antibodies (mAb) E11 and HB8592 bind to erythrocytes from all species examined and the number of mAb epitopes per erythrocyte correlated with the number of IC that could bind to the erythrocyte under saturating conditions. However, a number of interesting differences between the species are observed with other mAb. The anti-CR1 mAb 1B4 and 3D9, which block recognition of ligand by CR1, did not bind to chimpanzee erythrocytes and bound partially to rhesus and cynomolgus monkey erythrocytes. In addition, the ability of autologous serum to induce release of erythrocyte-bound IC correlates with the presence of these epitopes. These findings, taken in context with previous clearance studies, suggest that serum-mediated release may not be required for the rapid transfer of the IC from the erythrocyte to the mononuclear phagocytic system.

Animals↗
PubMed1992

Functional capacity of Fc gamma receptor III (CD16) on human neutrophils.

Receptors for the Fc region of immunoglobulin G (IgG) are a structurally diverse group of molecules. Within the three Fc gamma R families (Fc gamma RI, Fc gamma RII and Fc gamma RIII), the presence of distinct genes and alternative splicing variants leads to a variety of receptor isoforms that are most strikingly different in the transmembrane and intracellular regions. An obvious example of structural variation in the transmembrane and cytoplasmic domains is observed in the Fc gamma RIII family. Fc gamma RIIIB, which is nearly identical to Fc gamma RIIIA in the extracellular domains, lacks both transmembrane and cytoplasmic protein domains and is anchored to the cell through a glycosyl phosphatidylinositol anchor. Analysis of Fc gamma RIII function presents a considerable challenge in understanding the role of different Fc gamma R receptors in polymorphonuclear neutrophil (PMN) function. While one hypothesis for the role of Fc gamma RIII in Fc gamma R-dependent PMN effector functions is that Fc gamma RIII serves as a binding molecule which focuses the IgG ligand for more efficient recognition and intracellular signaling by Fc gamma RII, recent observations from a number of laboratories suggest that Fc gamma RIII on PMN can transduce signals across the membrane independent of ligand-dependent engagement of Fc gamma RII. We will review these data and present recent data which suggest that the role of Fc gamma RIII extends beyond direct initiation of functions to a more complex role of synergistic receptor interactions. These findings will be reviewed in the context of the experimental approaches that have been used to examine the roles of Fc gamma RII and Fc gamma RIII on PMN function.

Antibodies, Monoclonal↗
PubMed1992

Glucocorticoid therapy for rheumatic diseases.

Glucocorticoids are an essential therapeutic agent in the management of many inflammatory, autoimmune, and other rheumatic diseases. Perhaps because of their remarkable potency and widespread use, the literature on steroid treatment has tended to be rather anecdotal. Nonetheless, new information, both on the mechanism of action and on the clinical application, continues to become available. The complexity of the biology of steroid-receptor engagement and gene regulation is unraveling, and carefully designed clinical studies are helping to refine clinical application. However, for the clinician, the need for careful observation and sound judgment with glucocorticoid use remains critically important.

Glucocorticoids↗
PubMed1992

Allelic polymorphisms of human Fc gamma receptor IIA and Fc gamma receptor IIIB. Independent mechanisms for differences in human phagocyte function.

Two different allelic polymorphisms among the isoforms of human Fc gamma receptors have been defined: the low-responder (LR)-high-responder (HR) polymorphism of huFc gamma RIIA expressed on both PMN and monocytes and the NA1-NA2 polymorphism of the neutrophil Fc gamma RIII (huFc gamma RIIIB). To address the issues of whether the LR-HR polymorphism has a significant impact on Fc gamma R-mediated functions in human blood cells and whether any differences in LR-HR might be related to higher Fc gamma R-mediated phagocytosis in NA1 donors, we examined Fc gamma R-specific binding and internalization by donors homozygous for the two huFc gamma RIIA alleles. PMN from LR homozygotes showed consistently higher levels of internalization of erythrocytes opsonized with pooled human IgG (E-hIgG). The absence of an LR-HR phagocytic difference with erythrocytes opsonized with either anti-Fc gamma RIIA MAb IV.3 or rabbit IgG, as opposed to E-hIgG, suggested that the Fc piece of the opsonin might be important for this LR-HR difference. Accordingly, we studied HR and LR homozygotes with human IgG subclass-specific probes. Both PMN (independent of huFc gamma RIIIB phenotype) and monocytes from LR donors bound and internalized erythrocytes coated with human IgG2 (E-hIgG2) efficiently, whereas phagocytes from HR donors did so poorly. E-hIgG2 internalization was completely abrogated by blockade of the ligand binding site of huFc gamma RIIA with IV.3 Fab, indicating that huFc gamma RIIA is essential for the handling of hIgG2 and that the mechanism of the LR-HR phagocytic difference is at the level of ligand binding to huFc gamma RIIA. In contrast, the difference in internalization of E-hIgG between NA1 and NA2 homozygous donors was independent of the huFc gamma RIIA phenotype and did not manifest differences in ligand binding. Thus, the two known allelic polymorphisms of human Fc gamma R have distinct and independent mechanisms for altering receptor function, which may influence host defense and immune complex handling.

Adult↗
PubMed1992

Novel Fc gamma receptor I family gene products in human mononuclear cells.

Unlike the human Fc gamma RII and Fc gamma RIII families, which exhibit considerable diversity at both the nucleic acid and protein levels, the human Fc gamma RI family has only a single recognized product expressed as a 70-kD cell surface receptor with high affinity for monomeric IgG (hFc gamma RIa1). Using both polymerase chain reaction-based amplification and Northern hybridization, we document multiple interferon-gamma-inducible hFc gamma RI RNA transcripts in human mononuclear cells and neutrophils. The sequences of two of these Fc gamma RI related transcripts indicate that they are alternatively spliced products of a second Fc gamma RI family gene, termed Fc gamma RIB. The cDNA derived from the larger of these transcripts, termed hFc gamma RIb1, encodes a surface molecule that is not recognized by Fc gamma RI specific monoclonal antibodies when transfected into COS-7 cells. Unlike the interferon-gamma-inducible hFc gamma RIA gene product, hFc gamma RIb1 does not bind monomeric IgG with high affinity. However, both hFc gamma RIa1 and hFc gamma RIb1 do bind aggregated human IgG. Previously unrecognized diversity within the hFc gamma RI family includes an interferon-gamma-inducible, putative low affinity Fc gamma receptor that may play an important role in the mechanism by which Fc gamma receptors participate in the humoral immune response.

Amino Acid Sequence↗
PubMed1992

Patients with systemic lupus erythematosus at risk for Pneumocystis carinii pneumonia.

We describe 6 cases of patients with systemic lupus erythematosus (SLE) who developed Pneumocystis carinii pneumonia. All were treated with high dose corticosteroids, and all developed the infection within 4 months of beginning new or revised cytotoxic therapy. All patients tested (5 of 6) were negative for human immunodeficiency virus (HIV). Those patients who developed Pneumocystis carinii pneumonia had more severe lymphocytopenia (median 595 vs 833/mm3) and received higher doses of corticosteroids (median prednisone dose = 43 vs 20 mg/day) than other patients with active SLE. A threshold lymphocyte count of 350/mm3 identified 4 of 6 cases but only 1 of 20 controls. Patients with SLE treated with high dose corticosteroids and cytotoxic drugs and with severe lymphocytopenia may be at increased risk for this opportunistic infection.

Adult↗
PubMed1991

Regulation of phagocytosis and [Ca2+]i flux by distinct regions of an Fc receptor.

The binding of multivalent immunoglobulin G complexes to Fc receptors (Fc gamma Rs) on macrophages activates multiple immune functions. A murine macrophage cell line, but not a fibroblast cell line, that was transfected with human Fc gamma RIIA mediated phagocytosis and an intracellular Ca2+ concentration ([Ca2+]i) flux upon cross-linking of human Fc gamma RIIA. Transfected macrophages that expressed a truncated receptor lacking 17 carboxy-terminal amino acids phagocytosed small antibody complexes. However, only wild-type transfectants phagocytosed labeled erythrocytes and fluxed [Ca2+]i. Thus, the cytoplasmic domain of human Fc gamma RIIA contains distinct functional regions.

Animals↗
PubMed1991

Intravenous anti-D treatment of immune thrombocytopenic purpura: analysis of efficacy, toxicity, and mechanism of effect.

The efficacy, toxicity, and mechanism of effect of intravenous Anti-D (Winrho) were studied in 43 Rh+ patients with immune thrombocytopenia purpura (ITP) who had not undergone splenectomy and in three already splenectomized patients. The mean platelet increase for the 43 nonsplenectomized patients was 95,000/microL (median 43,000/microL). Children had greater acute platelet responses than did adults. Human immunodeficiency virus status and duration of thrombocytopenia did not affect response. Maintenance treatment was given to patients as needed: the average interval between infusions was 24 days. The three splenectomized patients had no platelet response whatsoever. Toxicity was minimal; infusions were completed in less than 5 minutes. The generally accepted mechanism of effect of Anti-D has been Fc receptor blockade by substitution of antibody-coated red blood cells for antibody-coated platelets. Evidence is presented suggesting that the effect of IV Anti-D is not limited to Fc receptor blockade, including: (1) no correlation of parameters of hemolysis with platelet increase; (2) a 48- to 72-hour delay before platelet increase; (3) a tendency of the change in monocyte Fc receptor I expression to correlate with platelet increase; and (4) increased in vitro production of antibodies to sheep red blood cells following IV Anti-D infusion.

Adult↗
PubMed1991

Fc gamma receptor III induces actin polymerization in human neutrophils and primes phagocytosis mediated by Fc gamma receptor II.

Human polymorphonuclear leukocytes (PMN) express two classes of Fc gamma R: Fc gamma RII the 42-kDa receptor with a traditional membrane spanning domain and cytoplasmic tail and Fc gamma RIIIPMN the 50- to 80-kDa receptor with a glycosyl-phatidylinositol membrane anchor expressed on PMN. To explore the capacity of Fc gamma RIIIPMN to generate intracellular signals, we have analyzed the ability of Fab and F(ab')2 anti-Fc gamma R mAb to induce actin filament assembly, a prerequisite for motile behaviors. Multivalent ligation of Fc gamma RIIIPMN, independent of Fc gamma RII, results in an increase in F-actin content that is [Ca2+]i dependent. Multivalent ligation of Fc gamma RII also initiates actin polymerization but uses a [Ca2+]i-independent initial pathway. In addition to providing a mechanism for Fc gamma RIIIPMN triggered effector functions, the increase in F-actin and [Ca2+]i generated by Fc gamma RIIIPMN ligation also serves as a "priming" signal to modify PMN responses to other stimuli. Experiments using erythrocytes specifically coated with anti-Fc gamma RII Fab demonstrate that cross-linking of Fc gamma RIIIPMN with anti-Fc gamma RIII F(ab')2 enhances phagocytosis mediated by Fc gamma RII. Thus, Fc gamma RIIIPMN, a glycosyl-phosphatidylinositol anchored protein, may contribute directly to an intracellular program of actin assembly that may trigger and prime neutrophil effector functions.

Actins↗
PubMed1991

A single amino acid distinguishes the high-responder from the low-responder form of Fc receptor II on human monocytes.

The low-affinity Fc receptor on human peripheral blood monocytes (Fc gamma RIIA) is polymorphic with respect to its ability to bind murine IgG1. The two allelic forms of the receptor, high responder (HR) and low responder (LR), yield characteristic patterns after isoelectric focusing and react differently with the anti-Fc gamma RII monoclonal antibody (mAb), 41H16. We recently cloned cDNA encoding the extracellular domains of Fc gamma RIIA on monocytes from one HR and two LR donors, and found that they differed at only a single base. The cDNA isolated from the HR donor had a G at position 519 and would be expected to encode an aginine at residue 133 in the mature protein, while the cDNA isolated from both LR donors had an A at position 519 and would be expected to encode a histidine at the same residue. To determine whether this single amino acid substitution actually accounts for the functional polymorphism involving Fc gamma RIIA, we transfected COS cells with full-length HR and LR Fc gamma RIIA cDNA, and examined them for their ability to react with anti-Fc gamma RIIA mAb and to bind red blood cells (RBC) coated with either murine IgG2b or murine IgG1. Whereas COS cells transfected with either the HR cDNA or the LR cDNA reacted with the anti-Fc gamma RII mAb, IV.3, and bound murine IgG2b-coated RBC, only COS cells transfected with the HR cDNA formed rosettes with murine IgG1-coated RBC and reacted strongly with mAb 41H16. A total of nine LR donors were identified, and all were homozygous for the A substitution at position 519. We conclude that at an A at position 519 in the cDNA encoding Fc gamma RIIA is the primary molecular basis for the LR form of the receptor, and that the amino acid at residue 133 determines whether Fc gamma RIIA efficiently binds murine IgG1.

Adult↗
PubMed1991

Mechanisms of action, dosage schedules, and side effects of steroid therapy.

Two themes are prominent in this year's literature dealing with glucocorticoids and musculoskeletal diseases. First, a high degree of attention has been focused on the use of high-dose intravenous methylprednisolone in rheumatoid arthritis. Despite a number of studies, however, opinion regarding its usefulness as a short-term, adjunctive therapy remains divided. Nonetheless, experience continues to support the view that intravenous methylprednisolone is associated with a relative lack of untoward effects. Second, attention has also been focused on steroid-induced osteoporosis. The heterogeneity of the impact of steroids on bone mineral density is perhaps surprising. The assumption that the effect of glucocorticoids on bone is uniformly large and sustained is clearly open to challenge, although the mechanisms underlying differences in host response are unclear. Definition of patients at higher risk for steroid-induced osteoporosis remains a priority.

Drug Administration Schedule↗
PubMed1991

Preferential expression of human Fc gamma RIIIPMN (CD16) in paroxysmal nocturnal hemoglobinuria. Discordant expression of glycosyl phosphatidylinositol-linked proteins.

The isoform of Fc gamma RIII (CD16) expressed on PMN has a GPI membrane anchor, and in paroxysmal nocturnal hemoglobinuria (PNH) there is a deficiency in Fc gamma RIII expression on PMN. Contrary to expectation, however, CD16 expression is preserved (albeit at reduced levels) in all affected PNH PMN that completely lack the GPI-anchored proteins DAF (CD55) and CD59. Fc gamma RIII negative PMN are not observed in any of the six PNH patients examined in this study. Analysis of the molecular weight of both glycosylated and deglycosylated Fc gamma RIII from PMN with reduced Fc gamma RIII expression indicates no variations in size relative to normal donor Fc gamma RIIIPMN. Indeed, the Fc gamma RIII expressed at intermediate levels is phosphatidylinositol-specific phospholipase C (PI-PLC)-sensitive. Thus, there is no evidence suggestive of expression of a transmembrane isoform and all data indicate that Fc gamma RIIIPMN on affected cells in PNH is a GPI-linked isoform. With Fc gamma RIIIPMN expression preserved at reduced levels on affected cells in PNH, PMN from PNH patients retain the capacity to internalize the Fc gamma RIIIPMN-specific probe E-ConA (at reduced levels) as well as IgG-opsonized erythrocytes. Reduced expression of GPI-anchored molecules on PNH PMN is not restricted to Fc gamma RIIIPMN since intermediate levels of CD59 were observed in the PNH PMN that were decay-accelerating factor (DAF)-negative and Fc gamma RIIIPMN intermediate. In addition, discordant expression of GPI-linked molecules in individual cells is not restricted to PMN since DAF+/CD14- monocytes were observed in one PNH patient. These data suggest that, when analyzed on an individual cell level, the GPI anchor defect in PNH is not absolute and must involve either a hierarchy of access of different protein molecules to available GPI anchors, distinct anchor biochemistries for the different proteins, or differential regulation of protein-anchor assembly.

Antigens, CD↗
PubMed1990

Fc gamma RIII expressed on cultured monocytes is a N-glycosylated transmembrane protein distinct from Fc gamma RIII expressed on natural killer cells.

Fc gamma RIII is a family of protein isoforms encoded by at least two distinct, yet highly homologous, genes. Fc gamma RIII on neutrophils is a glycosylphosphatidylinositol-linked protein with an allelic polymorphism (NA1/NA2) while Fc gamma RIII on NK cells (Fc gamma RIIINK) is an exclusively transmembrane protein without the NA polymorphism. The relationship of the isoform of Fc gamma RIII expressed on cultured monocytes (Fc gamma RIIIM phi) to these two forms, however, is unclear because some evidence suggests lowered expression of Fc gamma RIIIM phi in paroxysmal nocturnal hemoglobinuria (unlike Fc gamma RIIINK) and a unique deglycosylated m.w. for Fc gamma RIIIM phi. In this study we demonstrate that, as with Fc gamma RIIINK, Fc gamma RIIIM phi is resistant to the action of phosphatidylinositol-specific phospholipase C and is expressed at normal levels on affected (glycosylphosphatidylinositol-anchor negative) cultured monocytes from patients with paroxysmal nocturnal hemoglobinuria. Fc gamma RIIIM phi is also shed from the cell surface upon incubation at 37 degrees C. However, Fc gamma RIIIM phi and Fc gamma RIIINK have different m.w. as glycosylated proteins despite the same deglycosylated m.w. Thus, each cell type appears to express distinct glycoforms. These differences in glycosylation may influence the functional properties of the receptor.

Antigens, Differentiation↗
PubMed1990

The glycosyl phosphatidylinositol-linked Fc gamma RIIIPMN mediates transmembrane signaling events distinct from Fc gamma RII.

To investigate the ability of FcgammaRIII(PMN), the GPI-anchored isoform of FcgammaRIII (CD16) in polymorphonuclear leukocytes (PMN), to mediate transmembrane signaling events, we measured changes in membrane potential with DiOC(5) and in intracellular calcium with indo-1. FcgammaR were ligated by anti-FcgammaRIII mAb 3G8 (IgG and Fab), anti-FcgammaRII mAb IV.3 (IgG and Fab), and human IgG aggregates. Cell bound mAbs were also crosslinked by goat F(ab')(2) anti-mouse IgG. 3G8 IgG elicited a rapid change in [Ca(2+)](i), which was unaffected by EGTA, Vibrio cholerae toxin (CT), or Bordetella pertussis toxin (PT), and was abolished by BAPTA . Univalent receptor binding with 3G8 Fab gave no response but crosslinking with F(aV)2 GAM gave a rapid [Ca2,](i) response. Neither IV.3 Fab, IV.3 IgG, nor crosslinking of IV.3 Fab elicited a calcium signal. PI-PLC-treated PMN with the density of FcgammaRIII(PMN) reduced to that of FcgammaRII showed an unattenuated change in [Ca(2+)](i), with a 3G8 stimulus. The effects of IgG aggregates paralleled those of 3G8 mAb. These data indicate that multivalent ligation of FcgammaRIII(PMN) initiates an increase in [Ca(2+)];, derived from intracellular stores, that is distinct from both the FMLP- and FcgammaRII-induced responses. Ligand-dependent interaction with FcgammaRII is not required. Since FcgammaRIII(PMN) can internalize the FcgammaRIII-specific probe Con A-opsonized E and lyse anti-FcgammaRIII heteroantibody-opsonized chick E, this GPI-anchored molecule mediates both signal transduction and integrated cell responses.

Antibodies, Monoclonal↗
PubMed1990

Steroids.

Explore the source record for details and available documents.

Glucocorticoids↗
PubMed1990

Fc gamma receptor III on human neutrophils. Allelic variants have functionally distinct capacities.

As a model system to explore the functional consequences of structural variants of human Fc gamma receptors (Fc gamma R), we have investigated Fc gamma R-mediated phagocytosis in relation to the NA1-NA2 polymorphism of Fc gamma RIII (CD16) on neutrophils (Fc gamma RIIIPMN). The neutrophil-specific NA antigen system is a biallelic polymorphism with codominant expression demonstrating a gene dose effect with the anti-NA1 MAb CLB-gran 11 in a large donor population. To explore the impact of this allelic variation of Fc gamma RIIIPMN on phagocytosis, we used two Fc gamma RIII-dependent probes, IgG-sensitized erythrocytes (EA) and concanavalin. A-treated erythrocytes (E-ConA). Comparison of Fc gamma R-mediated phagocytosis by PMN from NA1 subjects and from NA2 subjects showed lower levels of phagocytosis of both probes by the NA2 individuals. The difference was most pronounced with lightly opsonized EA: at the lowest level of sensitization the phagocytic index was 72% lower for NA2 donors, whereas at the highest level of sensitization it was 21% lower (P less than 0.003). Blockade of Fc gamma RII with MAb IV.3 Fab amplified by threefold the difference between NA1 and NA2 donors. NA1 and NA2 individuals had identical phagocytic capacities for the non-Fc gamma RIII probes, serum-treated and heat-treated zymosan. These individuals did not show differential quantitative cell surface expression of Fc gamma RIIIPMN measured by a panel of anti-CD16 MAb (3G8, CLB FcR-gran 1, VEP13, BW209/2) and by Scatchard analysis of 125I-IgG dimer binding. The difference in Fc gamma R-mediated phagocytosis was not explicable on the basis of differential collaboration of Fc gamma RIIIPMN alleles with Fc gamma RII, since (a) the difference in phagocytic capacity between NA1 and NA2 individuals was readily apparent with the E-ConA probe (which is independent of Fc gamma RII) and (b) the difference in phagocytosis of EA was magnified by Fc gamma RII blockade. The demonstration that allelic polymorphisms in Fc gamma R can have significant consequences for physiological functions implies that within the structural complexity of human Fc gamma Rs, including both allelic forms and cell type-specific isoforms, there will be differences in quantitative, and perhaps qualitative, function with potential importance for disease processes.

Adult↗