Search PubMed⌕ Search

Biomedical subjects

R B Colvin

Publications and source records attributed to R B Colvin.

At least 163 records · Page 9Linked to original sources
PubMed1986

Responder strain-specific enhancement of endothelial and mononuclear cell Ia in delayed hypersensitivity reactions in (strain 2 X strain 13)F1 guinea pigs.

This study was undertaken to test the hypothesis that preferential responder strain-specific Ia expression can be detected in delayed hypersensitivity (DH) skin reactions. Seven adult (strain 2 X strain 13)F1 and two strain 13 guinea pigs were sensitized with poly-L glutamic acid-lysine (GL), poly-L glutamic acid-tyrosine (GT), and bovine insulin in complete Freund's adjuvant, and were skin tested with GL, GT, PPD, bovine insulin, porcine insulin (which has the same B chain as bovine insulin), and saline. Strain 2 guinea pigs react with bovine insulin A chain, GL, and PPD but not with GT or the bovine insulin B chain, whereas strain 13 guinea pigs react with bovine insulin B chain, GT, and PPD but not with GL or bovine insulin A chain. The (2 X 13)F1 animals had positive DH responses to GT, GL, PPD, and bovine insulin. At 24 hr, areas of induration were measured and the test sites and draining lymph nodes were biopsied. Cryostat sections were stained with monoclonal antibodies to strain 2 Ia, strain 13 Ia, and Ia framework determinants with immunoperoxidase. Stained dermal and subdermal inflammatory cells and vessels were counted on coded slides. In GT tests, there was more staining of dermal and subdermal cells and vessels for strain 13 Ia than strain 2 Ia (p less than 0.02). In bovine insulin tests there was more staining of dermal cells and vessels for strain 13 than strain 2 Ia (p less than 0.05). In GL tests there was more staining on dermal vessels and subdermal cells and vessels of strain 2 Ia than strain 13 Ia (p less than 0.05). There was much greater staining of strain 2 Ia of dermal cells and vessels in GL tests compared with strain 2 Ia staining in GT and bovine insulin tests (p less than 0.02, cells; p less than 0.01, vessels). No significant differences between strain 2 and strain 13 Ia expression were found in PPD, porcine insulin tests, saline controls, or in lymph nodes that drained sensitization sites from animals in which GL and GT had been injected on different sides. Anti-Ia framework expression generally correlated with the greater parental strain Ia in each reaction. These findings and previous observations in experimental allergic encephalomyelitis suggest that responder type Ia may be selectively found in vivo on mononuclear and endothelial cells in sites of T cell-mediated hypersensitivity reactions.

Animals↗
PubMed1986

Dietary fish oil reduces progression of established renal disease in (NZB x NZW)F1 mice and delays renal disease in BXSB and MRL/1 strains.

Previous studies have shown that dietary marine lipids containing large quantities of n-3 polyunsaturated fatty acids, administered to (New Zealand black X New Zealand white)F1 and MRL-lpr/lpr mice before the development of renal disease, reduce the severity of glomerulonephritis in mice of these strains. The present study demonstrated that delayed administration of a marine lipid diet, 25% menhaden oil (MO) by weight, until after the onset of overt renal disease, also resulted in significant improvement in rates of mortality, proteinuria, and histologic evidence of glomerular injury, compared with control animals fed a diet that contained mostly saturated fatty acids, 25% beef tallow. The MO diet also reduced the histologic severity of renal disease in male BXSB/MpJ and male MRL-lpr/lpr mice. In contrast, necrotizing vasculitis was more frequent in small and medium-sized renal arteries of the MRL-lpr/lpr mice fed MO than in those fed beef tallow (33.4% versus 7.6%, respectively).

Animals↗
PubMed1986

Usual interstitial pneumonitis is a T-cell alveolitis.

Usual interstitial pneumonitis (UIP) is an idiopathic inflammatory disorder that produces scarring of the lung parenchyma. We studied open-lung biopsies of 13 patients with UIP using immunohistological staining and monoclonal antibodies. T lymphocytes (Leu 4+) accounted for 59% of cells in the alveolar septal infiltrates in UIP and OKT8+ cells accounted for the majority of T lymphocytes in most cases. OKM1+ granulocytes comprised a smaller percentage (14%) of the alveolar infiltrates. Granulocytes were most frequent within cystic airspaces and inflamed small airways. Class II HLA (Ia) antigens were expressed on lymphocytes, macrophages, endothelial cells, and alveolar type II cells in lungs with UIP. This study demonstrates that altered immunoregulatory subsets are present in the lungs of patients with UIP and suggests the possibility that activated T cells may play a role in the pathogenesis of this disorder.

Adult↗
PubMed1986

Leu-M2 (Mac-120) is a platelet antigen and is not constitutively expressed by macrophages.

Leu-M2 (Mac-120) is a mouse anti-human monoclonal antibody that reacts with an antigen on the surface of most peripheral blood monocytes. The presence of Leu-M2 positivity has been associated with the capacity of monocytes to present antigen to T cells. We found that anti-Leu-M2 does not react with an intrinsic monocyte antigen but instead binds to platelets present on the surface of monocytes. Leu-M2 staining is lost from monocytes after they are treated with calcium chelating agents which remove platelets bound to the monocyte surface. Staining for Leu-M2 can be reintroduced by incubating monocytes with autologous platelets. Human alveolar, peritoneal, and tissue macrophages and the U937 cell failed to stain for Leu-M2 antigen. Leu-M2 does not appear to represent either platelet glycoprotein IIb/IIIa or thrombospondin. Our study underscores the importance of carefully screening antimonocyte antibodies for their reactivity with platelets.

Antibodies, Monoclonal↗
PubMed1986

Monoclonal antibody therapy. Anti-idiotypic and non-anti-idiotypic antibodies to OKT3 arising despite intense immunosuppression.

The frequency, timing, and specificity of the humoral antibody response to a murine monoclonal antibody (OKT3, IgG2a) were measured in 21 consecutive renal allograft recipients. These patients received i.v. OKT3, 1-5 mg/day for 10-20 days as treatment for acute graft rejection. Maintenance immunosuppression consisted of azathioprine and corticosteroids. Using three different assays, an antibody response was detected in 75% of the 20 patients with adequate samples. The ELISA assay of the overall IgM and IgG reactivity to OKT3 revealed that IgM anti-OKT3 appeared in 65% and IgG anti-OKT3 in 50% of the patients, reaching a peak 20-33 days after the last dose of OKT3. The IgM preceeded the IgG in most cases (P less than 0.02) and in 8 cases was detected during therapy. One patient had high levels of IgM anti-OKT3 before therapy, yet responded normally to OKT3. Interference with the therapeutic effectiveness was evident in one patient who developed IgG antibodies during therapy. His serum blocked the binding of F-OKT3 to normal lymphocytes in the presence of normal BALB/c serum. The blocking assay, done by flow cytometry, measured anti-idiotypic (Id) reactivity since the sera did not affect the binding of OKT8 (another IgG2a) or anti-Leu4 (another anti-T3), and the blocking activity remained after affinity absorption with normal mouse IgG. Using this assay, 60% of the patients made an anti-Id response. One made only anti-Id, and several had anti-Id at times when other reactivities were undetectable. Antibodies to non-idiotypic, presumably isotypic, determinants represented on OKT8 occurred in only 44%, while other reactivity (OKT4; IgG2bK) was less common (12%) and weaker. While no adverse allergic reactions occurred in this group of patients, the anti-Id antibodies, which are a prominent feature of the immune response to this and probably other monoclonal antibodies, can block their therapeutic effectiveness and can arise despite intense immunosuppression. This response may require the use of different idiotypes for prolonged or repeated courses of therapy and may be the major obstacle to the use of human monoclonal antibodies.

Antibodies, Anti-Idiotypic↗
PubMed1986

OKT3 monoclonal antibody plasma levels during therapy and the subsequent development of host antibodies to OKT3.

OKT3 levels and the presence of human antibodies to OKT3 were determined in the plasma of 66 patients receiving OKT3 monoclonal antibody (5 mg i.v. daily) for the treatment of acute renal allograft rejection. Plasma 24-hr trough levels of OKT3 rose over the first three days and then remained in a steady state over the remainder of the 14-day period of OKT3 therapy, with a mean level of 902 +/- 71 ng/ml (mean + SEM). On termination of OKT3 therapy plasma levels of OKT3 dropped to very low levels after 3 days. Host antibodies, usually of low titer, developed in a number of patients, usually 2-3 weeks after the start of OKT3 therapy. 37/43 patients (86%) who received OKT3 alone developed IgG anti-OKT3 antibodies; 9/23 patients (39%) who received Cytoxan in addition to OKT3 developed IgG anti-OKT3 antibodies, a significantly lower (P = 0.0002) incidence. The present regimens permitted maintenance of adequate levels of circulating OKT3 for 2 weeks, a sufficient time to reverse acute renal allograft rejection in most patients.

Antibodies, Anti-Idiotypic↗
PubMed1986

Response of pulmonary macrophages to hyperoxic pulmonary injury. Acquisition of surface fibronectin and fibrin/ogen and enhanced expression of a fibronectin receptor.

The in vivo acquisition of coagulation plasma proteins on the surface of pulmonary macrophages was studied in guinea pigs breathing 95% oxygen. Fibrin/ogen and fibronectin appeared rapidly and concurrently on the surfaces of macrophages in the bronchoalveolar lavage fluid, which was judged by immunohistologic examination and flow cytometry. Pulmonary macrophages showed a parallel increase in the expression of a surface fibronectin receptor. Hyperoxic lung injury was accompanied by deposition of an extravascular pulmonary matrix of fibronectin and fibrin/ogen and depressed plasma levels of fibronectin. Binding to clot matrix proteins may lead to aggregation and retention of macrophages at sites of acute lung injury as well as alteration of cell function.

Animals↗
PubMed1986

Induction of MHC-determined antigens in the lung by interferon-gamma.

Recombinant murine interferon-gamma (IFN-gamma) was administered in 6 to 9 daily intraperitoneal injections to B10.BR (H-2k) mice. The distribution of some selected class I and II major histocompatibility complex-determined antigens was localized by immunocytochemistry with the use of anti-H-2Kk and anti-IAk monoclonal antibodies and avidin-biotin-peroxidase in unfixed, frozen lungs for light microscopy and in fixed lungs for electron microscopy. In normal control mice no class I antigens were detected in the lung either by light microscopy or by ultrastructural immunocytochemistry. After 6 to 9 days of IFN-gamma administration, class I antigens were detectable on the endothelium of major vessels and diffusely throughout the alveolar region, presumably on alveolar capillary endothelium. Class I antigens did not withstand chemical fixation, therefore, could not be localized at the ultrastructural level. In normal, control mice class II antigens were detectable on a few interstitial macrophages, on some circulating monocytes, and on elongated cells adjacent to airways and major vessels. After 6 to 9 daily injections of IFN-gamma, larger numbers of macrophages and elongated cells, believed to be dendritic cells, were present around major airways and vessels. In addition, numerous round cells stained throughout the alveolar region. By electron microscopy these round cells included intraalveolar macrophages, although not all alveolar macrophages expressed IAk, circulating monocytes in capillary lumens, and type II pneumocytes. Type I pneumocytes had no detectable IAk. Reaction product in type II cells was limited to the basolateral membranes. Airway epithelium and endothelium remained unstained. These observations indicate that in addition to monocytes/macrophages IFN-gamma induces the expression of class II antigens on type II pneumocytes.

Animals↗
PubMed1986

The in situ cellular immune response in acute herpes simplex encephalitis.

To characterize the in situ cellular immune response in acute herpes simplex encephalitis (HSE), the authors stained frozen brain specimens from 19 patients with HSE and 8 controls with a panel of monoclonal antibodies, which allowed them to identify inflammatory cell subsets and expression of activation markers and major histocompatibility complex (MHC) molecules. Parenchymal and meningeal inflammatory infiltrates were composed of T cells, with fewer natural killer and B cells, and variable numbers of granulocytes and macrophages. T4+ and T8+ cells were present in equal numbers. Inflammatory cells expressed interleukin-2 receptor, MHC Class I (HLA-alpha chain, beta-2 microglobulin), and MHC Class II (HLA-DR, HLA-DQ) molecules. There was increased MHC molecule expression in HSE on resident cells, including neurons and vascular endothelium, and vascular expression of HLA-DR was greater than that of HLA-DQ (P less than 0.01). No correlations between immune parameters with amount of corticosteroid therapy or duration of illness before biopsy was performed or outcome were found. T cell-mediated cytotoxic and delayed hypersensitivity mechanisms may contribute to tissue injury in HSE.

Antibody Formation↗
PubMed1986

Macrophage migration in fibrin gel matrices.

Macrophage migration has been extensively studied in vitro on artificial substrates but in vivo macrophages migrate through connective tissue and fibrin gel meshworks that comprise the stroma of many inflammatory reactions and solid tumors. Studies were therefore undertaken to investigate macrophage migration in this more biologically relevant matrix cast either with or without nitrocellulose filter support. Macrophage migration in fibrin gels depended on both fibrin and thrombin concentrations and on the nature of fibrin crosslinking. With gamma-chain crosslinking only, macrophage migration was enhanced as compared with untreated filters at fibrin concentrations of up to 5 mg/ml. However, when fibrin alpha-chains were also crosslinked, as occurs in vivo, macrophage migration was inhibited at approximately 3 mg/ml fibrin and was stopped altogether at 5 mg/ml. Thrombin concentrations of 1 unit/ml favored maximal macrophage migration. Depletion of contaminating fibronectin did not affect these results. The pore size of fibrin gels is well below the minimum that permits macrophage migration through nitrocellulose filters. Thus, to penetrate fibrin gels, macrophages could enlarge effective pore size by local fibrinolysis or by pushing apart fibrin strands. If fibrinolysis is responsible, this process must be highly localized because only small amounts of fibrinolysis accompanied extensive macrophage migration in fibrin gels; moreover, fibrinolysis inhibitors did not affect macrophage migration. We conclude that the fibrin deposited in inflammatory reactions and solid tumors is present in forms and concentrations that either facilitate or inhibit macrophage migration; fibrin may therefore regulate macrophage participation in these and other pathologic reactions.

Animals↗
PubMed1985

Widespread and selective induction of major histocompatibility complex-determined antigens in vivo by gamma interferon.

gamma Interferon (IFN-gamma) caused remarkable increases in class I (H-2Kk) and class II (I-Ak) antigens throughout the body by 6-9 d. Heart, kidney, and adrenals showed increases of 4-8 times their previous levels of class I antigen content, while the pancreas and small intestine increased 13-17-fold. Lesser increases were found in spleen, liver, and lung, which showed higher resting antigenic potency. Increases of class II antigenicity of 6-10-fold were found in heart, kidney, pancreas, lung, liver, adrenal, and small intestine, with lesser increases in thymus and spleen, and none in lymph node. Topographical analysis revealed that IFN-gamma induced class I and II antigens on most tissues in a highly selective fashion. For example, the renal proximal tubules expressed large amounts of both class I and II antigens, whereas the distal tubules and collecting ducts did not. In some epithelial cells class I and II determinants were induced only on the basal aspects of the cell membrane. IFN-gamma caused a remarkable increase in class II-positive dendritic cells in the liver, pancreas, salivary glands, and thyroid. Whether these cells were of local or systemic origin is uncertain, but the finding of a simultaneous depletion of dendritic cells from lymph nodes and spleen raises the possibility that they may have been derived, at least in part, from these sites. The dynamic and selective induction of class I and II antigen expression by IFN-gamma is likely to be important in regulation of the immune response in tissues.

Animals↗
PubMed1985

Immunoferritin electron microscopic studies with antibasophil serum of guinea pig basophil degranulation and regranulation in vitro.

We have previously shown that degranulated guinea pig basophils in vitro do not die. Rather, they recover, and these mature cells rebuild granules in the absence of nuclear changes of immaturity or of mitoses. This ability to survive the explosive release of cytoplasmic granules and to rebuild granules was the first such demonstration for a mature granulocyte. We utilized this model of antigen-induced basophil degranulation and recovery in vitro, in conjunction with a specific antibasophil serum (ABS) and indirect immunoferritin electron microscopy, in order to localize the anatomic sites of expression of the antigen(s) recognizing ABS during the secretory and recovery events. Basophil surface membranes were labeled prior to degranulation, during degranulation, after degranulation, and as mature, polynuclear, granule-free cells began to rebuild new granules. In addition, the plasma membranes of non-granule-containing, glycogen positive, small mononuclear cells were labeled. These were few in number and were thought to be precursor cells in the basophil lineage. Controls, either nondegranulated basophils at a variety of culture intervals, or basophils following degranulation and during recovery, were done using normal rabbit serum (NRS) and an indirect immunoferritin electron microscopic technique. These were all negative. Moreover, contaminating eosinophils, neutrophils, and lymphocytes were also negative. Extruded granules were labeled with ferritin (ABS) on their membrane-free, finely granular exteriors, but not within the lamellar array of their matrixes. Extruded granules were not labeled in control experiments. When tested with ABS, membrane-bound granules in the cytoplasm prior to release and membrane-free, released granules contained within degranulation sacs, were negative, as was the membrane of sacs. Immature, membrane-bound granules were also negative. Ferritin binding to membranes was seen in narrow channels, vesicles, and larger vacuoles, as well as in multivesicular bodies, present in the peripheral cytoplasm. This distribution of labeled sites was not observed in neutrophils, eosinophils, and lymphocytes which were also routinely present in these preparations. These sites were not labeled in basophils or other cells in control studies using ferritin and NRS. This indicates the necessity for specific binding to basophils in order to visualize this process. Whether most such sites represent residual endocytosis at 4 degrees C or binding to open invaginations near surfaces of cells does not detract from their specificity and thus expression of specific antigen(s)-binding sites in basophils.

Animals↗
PubMed1985

The immunopathology of experimental allergic encephalomyelitis (EAE). III. Differential in situ expression of strain 13 Ia on endothelial and inflammatory cells of (strain 2 x strain 13)F1 guinea pigs with EAE.

This study was undertaken to determine if there is differential expression of the relevant strain-specific Ia antigen on endothelial and parenchymal inflammatory cells in the central nervous systems (CNS) of guinea pigs (GP) with acute experimental allergic encephalomyelitis (EAE). Adult inbred GP were sensitized with GP spinal cord homogenate and complete Freund's adjuvant. Strain 13 GP and (2 x 13)F1 hybrids developed clinical disease within 2 to 3 wk after sensitization, whereas strain 2 GP did not, although all sensitized GP had CNS mononuclear inflammatory infiltrates. By using monoclonal antibodies to strain-specific and framework Ia epitopes with an immunoperoxidase technique, the distribution and amount of the strain 2 and strain 13 Ia were analyzed. Equivalent strain 2 and strain 13 Ia expression was found in normal tissues from F1 animals. Strain 2 and strain 13 GP sensitized for EAE had increased strain-specific Ia staining of CNS vessels and inflammatory cells over controls. However, F1 GP with EAE had markedly increased strain 13, but not strain 2, Ia on CNS parenchymal vessels and mononuclear inflammatory cells (p less than 0.001, for both). These results suggest for the first time that specific major histocompatibility complex gene products are selectively expressed on endothelial and inflammatory cells in situ in immune reactions in the target organ of individuals of heterogeneous immunogenetic composition.

Animals↗
PubMed1984

A flow cytometric technique for quantitation of B-cell activation.

A flow cytometric method for enumeration of intracytoplasmic antibody-containing cells was developed. Flow cytometry was found to yield results comparable to traditional fluorescence microscopy in cells stimulated to produce intracytoplasmic antibody by either pokeweed mitogen or Epstein-Barr virus. This technique offers several advantages over traditional fluorescence microscopy, including objective measurement of fluorescence intensity and rapid analysis of large numbers of cells.

Antibody-Producing Cells↗
PubMed1984

Antigenic polymorphism of the T4 differentiation antigen expressed on human T helper/inducer lymphocytes.

The human TH lymphocyte population has been established to express a differentiation antigen (T4) which appears to function in cellular collaboration and T cell recognition of Class II MHC alloantigens. Because we observed altered immunofluorescence staining of the TH cells of some individuals using the OKT4 mAb, a systematic investigation on both the epitopic structure of the T4 glycoprotein molecule and possible polymorphism of these epitopes was undertaken. From competitive blocking assays using eight murine anti-T4 mAbs coupled with quantitative flow cytometry, at least five and possibly seven different epitopes can be recognized on the T4 molecule. Population studies showed some individuals had a reduced phenotypic expression of the OKT4 reactive determinant to one-half that of normal and others completely lacked this epitope. The OKT4 reactive epitope variations are common but have so far been racially restricted to American Blacks and do not appear related to the stage of TH cell differentiation, any identifiable immune abnormality in vitro, or a definable disease process. The OKT4 epitope cannot be unmasked by neuraminidase treatment or T cell stimulation with lectins, soluble antigens, or allogeneic lymphocytes. Coupled with a family study, the alterations in OKT4 phenotype are best explained by autosomal, codominant expression of the T4 gene product. The significance of this polymorphism on TH cell function remains unclear.

Antibodies, Monoclonal↗
PubMed1984

Basement membrane components in healing rabbit corneal epithelial wounds: immunofluorescence and ultrastructural studies.

The nature of the substrate that supports epithelial migration in vivo is of interest, particularly with respect to mechanisms of wound healing. Immunofluorescence and electron microscopy were used to search for common substrate components in prototype rabbit corneal wounds: epithelial scrape wounds, in which the corneal or conjunctival epithelium migrated over the denuded lamina densa of the corneal basement membrane (CBM), and superficial keratectomy, in which the corneal epithelium migrated over a bare stroma without CBM. The corneal epithelium moved rapidly over the CBM or stroma to cover the defect within 2-3 d, whereas the conjunctival epithelium required 1-2 wk. In all wounds, fibronectin and fibrin/fibrinogen were deposited onto the bare surface within 8 h after wounding and persisted under the migrating epithelium until migration was complete. Bullous pemphigoid antigen (BPA), a normal component of the CBM, was removed with the epithelium upon scrape wounding and reappeared in the CBM after migration was completed. In contrast, the conjunctival epithelium had a continuous subepithelial band of BPA out to the migrating tip. Laminin, also a normal component of the CBM, was not removed in the scrape wounds, indicating that the region of least resistance to shear stress was between the BPA and laminin layers. Laminin was removed by superficial keratectomy and was not detectable under the leading edge of the migrating cells. Laminin and BPA were restored in the CBM by 2-4 wk. Type IV collagen could not be detected in normal CBM, but was conspicuously present in conjunctival basement membrane and in blood vessels. Focal bands of type IV collagen did appear in the newly synthesized CBM 2-4 wk after keratectomy. These results argue that BPA, laminin, and type IV collagen are not essential for the migration of corneal epithelium during wound healing and support the hypothesis that fibronectin and fibrin/fibrinogen are the common, perhaps the essential, components of the provisional matrix that serves as a substrate until the permanent attachment components are regenerated.

Animals↗