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Biomedical subjects

P A Morel

Publications and source records attributed to P A Morel.

At least 19 recordsLinked to original sources
PubMed1995

HLA and ethnic associations among systemic sclerosis patients with anticentromere antibodies.

SSc with ACAs is characterized by limited cutaneous involvement and, in most patients, a mild protracted course. We have studied 104 SSc patients, 47 with ACAs and 57 who were negative for both ACAs and anti-topo I antibodies, for HLA-DR and -DQ associations using DNA typing techniques. Normal controls consisted of 181 healthy individuals. A significant association was observed in the ACA-positive patients with DQB1-0501 (p = 0.001, RR 2.6). There was also a significant decrease in the frequency of DQB1-0201 (p = 0.01, RR 0.33). In addition, the ACA-positive SSc patients were significantly different ethnically from both the other SSc patients and the normal controls (p = 0.004). When patients were stratified according to their ethnic origin and the analysis of HLA associations was repeated, the HLA associations persisted. These results strongly suggest that the development of SSc with ACAs is associated with particular DQB1 alleles, and also that ethnic origin plays a role in disease susceptibility.

Adult↗
PubMed1995

Generation of DC from mouse spleen cell cultures in response to GM-CSF: immunophenotypic and functional analyses.

In all tissues that have been studied to date, dendritic leucocytes constitute only a small proportion of total cells and are difficult both to isolate and purify. This study reports on a method for the propagation of large numbers of dendritic cells (DC) from mouse spleen using granulocyte-macrophage colony-stimulating factor (GM-CSF) and their characteristics. Within a few days of liquid culture in GM-CSF, B10 BR (H-2k, I-E+) mouse splenocytes formed loosely adherent myeloid cell clusters. Mononuclear progeny released from these clusters at and beyond 4 days exhibited distinct dendritic morphology and strongly expressed leucocyte common antigen (CD45), CD11b, heat-stable antigen, Pgp-1 (CD44) and intercellular adhesion molecule-1 (ICAM-1; CD54). The intensity of expression of the DC-restricted markers NLDC 145 and 33D1, the macrophage marker F4/80, and Fc gamma RII (CDw32) was low to moderate, whereas the cells were negative for CD3, CD45RA and NK1.1. High and moderate levels, respectively, of cell surface staining for major histocompatibility complex (MHC) class II (I-Ek) and the B7 antigens (counter-receptors of CTLA4, a structural homologue of CD28) were associated with potent stimulation of unprimed, allogeneic T cells (B10; H-2b, I-E-). DC propagated in a similar fashion from DBA/2 mouse spleen proved to be strong antigen-presenting cells (APC) for MHC-restricted, syngeneic T-helper type 2 (Th2) cell clones specifically responsive to sperm whale myoglobin. Footpad or intravenous injection of GM-CSF-stimulated B10.BR spleen-derived DC into B10 (H-2b, I-E-) recipients resulted in homing of the allogeneic cells to T-cell-dependent areas of lymph nodes and spleen, where they strongly expressed donor MHC class II antigen 1-2 days later. These findings indicate that cells can be propagated from fresh splenocyte suspensions that exhibit distinctive features of DC, namely morphology, motility, cell-surface phenotype, potent allogeneic and syngeneic APC function and in vivo homing ability. Propagation of DC in this manner from progenitors present in lymphoid tissue provides an alternative and relatively convenient source of high numbers of these otherwise difficult to isolate but functionally important APC.

Animals↗
PubMed1994

Severe systemic sclerosis with anti-topoisomerase I antibodies is associated with an HLA-DRw11 allele.

SSc is an autoimmune connective tissue disease in which strong HLA associations have not been described. Anti-topo I antibodies are recognized, in general, in SSc patients with diffuse cutaneous involvement, whereas anti-ACAs are found in individuals with limited cutaneous involvement. We studied 95 Caucasian SSc patients, 44 with anti-topo I antibodies and 51 with neither anti-topo I nor ACA, for HLA-DR associations by using DNA typing techniques. We analyzed 181 normal Caucasian individuals in the same fashion. A significant association was observed in the anti-topo-I-positive patients with DRw11 (p = 1.7 x 10(-6), RR 4.2). The distribution of DRw11 alleles in these patients was significantly different from that observed in controls and could be accounted for by an increase in the frequency of the DRB1*1104 allele (p = 1.2 x 10(-9), RR 9.5). The DRw11 alleles were also associated with SSc with more tendon friction rubs (p = 0.006), which is a marker of more severe disease. In addition, a strong association was observed with anti-topo I antibodies and a particular sequence (aa 71-77) of the DQB1 chain (p = 0.02, RR 2.2). HLA associations in the case of SSc patients with anti-topo I antibodies are complex and involve at least two genes: HLA-DRw11, which appears to play a major role in determining the severity of the disease, and a DQ sequence, which associates with the development of the anti-topo I antibodies.

Adult↗
PubMed1993

Characterization of the Fc mu receptor on human natural killer cells. Interaction with its physiologic ligand, human normal IgM, specificity of binding, and functional effects.

After treatment with human normal IgM, 78 +/- 8% of purified CD3-CD56+ resting human NK cells and 93 +/- 6% of IL-2-activated NK cells selected by adherence to plastic reacted with FITC-goat anti-human IgM. Binding of IgM to the FcR for IgM (Fc mu R) on human NK cells was not species specific because mouse myeloma IgM also bound to these cells. The percentage of CD56+ cells binding IgM after incubation with anti-CD16 mAb was similar to that of cells incubated with medium alone (95 +/- 1% vs 93 +/- 4%). Binding of anti-CD16 mAb to Fc gamma RIII on NK cells was unaffected by pretreatment with IgM (65 +/- 12% vs 69 +/- 4%). The CD7 molecule has been reported to be the Fc mu R on the surface of T cells. Two-color flow cytometry showed that 94 +/- 3% of CD3-CD56+ resting NK cells and 71 +/- 16% of activated NK cells were CD7+. Preincubation of NK cells with three anti-CD7 mAb (Leu-9, 8H8-1, and LAU-A1) failed to block the binding of IgM to the Fc mu R. Modulation of the CD7 molecule off the cell surface (CD7+ = 1.5% +/- 0.3) did not reduce IgM binding, thus excluding the possibility that IgM anti-CD7 might bind to different epitopes of the same molecule. These data indicate that the Fc mu R is a specific Ig-binding structure, distinct from the Fc gamma RIII (CD16) or CD7. The Fc mu R on NK cells functions as a signal-transducing molecule because the addition of 0.2 mg/ml IgM to R-NK cells caused a rapid increase in [Ca2+]i (delta = 40 nM). One of the early events that followed signaling through the Fc mu R was the down-modulation of IFN-gamma gene expression and IFN gamma production in NK cells. The presence of IgM during culture of NK cells consistently decreased the expression of HLA-DR (16% vs 40% in control). Thus, the Fc mu R, a constitutively-expressed receptor on human NK cells, seems to be an important functional molecule, which delivers negative regulatory signals to NK cells.

Antigens, CD↗
PubMed1993

A dual mechanism of immunosuppression by FK-506. Differential suppression of IL-4 and IL-10 levels in T helper 2 cells.

FK-506 is known to suppress the transcription of several genes encoding cytokines (e.g., IL-2, IFN-gamma) thought to play an important role in the allograft response. This general inhibition of cytokine gene transcription and protein production was previously thought to be the main mechanism by which FK-506 suppressed the immune response. We have studied the pattern of cytokine suppression caused by FK-506 in differentiated murine Th 2 cell lines. Supernatants from Th2 cells treated with FK-506 showed marked suppression of IL-4 but only moderate suppression of IL-10 levels. To determine whether this differential effect on IL-4 and IL-10 could also be seen at the mRNA level, total cellular RNA was isolated from cells treated with (1) media, (2) Con A (2 micrograms/ml), (3) FK-506 (50 ng/ml), or (4) Con A + FK-506. Reverse transcription-polymerase chain reaction and northern blot analysis were used to measure IL-4 and IL-10 mRNA. Similar to results at the protein level, FK-506 suppressed steady state levels of IL-4 mRNA markedly but had a lesser effect on steady state levels of IL-10 mRNA. Furthermore, FK-506 completely abrogated Con A-induced upregulation of IL-4 mRNA, but only slightly suppressed Con A-induced upregulation of IL-10 mRNA. IL-10 (cytokine synthesis inhibitory factor) is a cytokine with immunosuppressive properties that itself inhibits the production of IL-2 and IFN-gamma murine helper cells. IL-10 also downregulates MHC II expression and antigen presentation by monocytes. Therefore, the ability of FK-506 to differentially suppress the mRNA levels of immunostimulatory cytokines such as IL-2, IL-4, and IFN-gamma more than the mRNA levels of the immunosuppressive cytokine IL-10 suggests that the effective immunosuppression seen in vivo with FK-506 may be a combination of these 2 effects.

Animals↗
PubMed1992

Modulation of myeloid proliferation and differentiation by monoclonal antibodies directed against a protein that interacts with the interleukin-3 receptor.

Hematopoietic cells can be transformed through the acquisition of autocrine growth factor production. Because of their ability to inhibit autocrine growth, antibodies directed against the growth factor or its receptor may have therapeutic potential. However, these agents may also inhibit normal cell development. We have developed two monoclonal antibodies, 4G8 and 2F2, directed against a protein of 110 to 150 Kd that interacts with the interleukin-3 (IL-3) receptor (R) complex. These antibodies inhibit IL-3-induced proliferation of nonleukemic and leukemic IL-3-dependent cell lines, as well as the autonomous growth of WEHI-3B in vitro and in vivo. These results suggest the possibility that anti-IL-3R antibodies may be useful in the treatment of some leukemias. However, the effect of anti-IL-3R antibodies on normal myeloid development in vitro has not been examined. We examined the effect of 4G8 and 2F2 on the growth in vitro of colony-forming unit granulocyte-macrophage (CFU-GM) colonies induced by IL-3, granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage CSF (GM-CSF), and macrophage-CSF (M-CSF). Our results show that while 4G8 and 2F2 inhibited CFU-GM colony formation induced by IL-3, they augmented colony formation induced by the other hematopoietins. 4G8 and 2F2 also enhanced G-CSF-induced proliferation of 32Dc13 and GM-CSF-induced proliferation of PT18, confirming that the effect on CFU-GM was a direct effect. Finally, 4G8 and 2F2 inhibited G-CSF-induced differentiation of 32Dc13, similar to low levels of IL-3; yet, neither 4G8 nor 2F2 blocked binding of G-CSF to its receptor. These results indicate that, in the absence of IL-3 and in the presence of other hematopoietins, 4G8 and 2F2 can function as weak IL-3 agonists. These studies suggest that antibodies such as 4G8 and 2F2, directed against components of the IL-3R, could potentially augment myeloid growth in vivo, rather than inhibit myeloid growth.

Animals↗
PubMed1991

Inhibition of growth of mouse leukemic cell lines in vitro and in vivo by a monoclonal antibody that recognizes an interleukin 3 receptor-associated protein.

Myeloid cell lines that have achieved leukemic transformation may also have acquired the ability to produce hematopoietic growth factors. In certain instances, neutralizing antibodies directed against the growth factor have inhibited growth, supporting an autocrine mechanism in their transformation. The effect of anti-receptor antibodies on their growth and transformed phenotype has not been reported. We have developed a monoclonal antibody, 4G8, directed against a protein that is associated with the IL-3 receptor complex; 4G8 inhibits IL-3 binding and signal transduction in nonleukemic IL-3-dependent cell lines. In this study, we examined the effect of 4G8 on the growth in vitro and in vivo of leukemic cell lines, including WEHI-3B, which spontaneously produces IL-3, and NFS-60, an IL-3-dependent cell line. Our results demonstrate that the 4G8 antigen can be detected in both WEHI-3B and NFS-60 cells by flow cytometry and Western blotting; 4G8 inhibits the autonomous growth of WEHI-3B and the IL-3-dependent growth of both WEHI-3B and NFS-60. In addition, s.c. administration of 4G8 prolonged the survival of syngeneic mice given s.c. injections of WEHI-3B. These results support the conclusion that an autocrine mechanism involving IL-3 and its receptor plays a critical role in the growth and transformed phenotype of WEHI-3B and raises the possibility that anti-IL-3 receptor antibodies may be useful in the treatment of some leukemias.

Animals↗
PubMed1991

Identification of a novel protein capable of interacting with the IL-3 receptor.

IL-3 has numerous functions in hematopoiesis yet its receptor has not been fully characterized. We have developed two mAb, 4G8 and 2F2, that markedly inhibited IL-3-dependent proliferation whereas only marginally affecting IL-2 or IL-4-induced proliferation. On Western blots, both antibodies identified the same protein, which varied in size from 115 to 145 kDa in six cell lines tested. The 4G8/2F2 Ag was detected at moderate density, on a wide variety of cells including IL-3-dependent cell lines and T lymphocytes. Radioligand binding studies revealed that 4G8, but not 2F2, could inhibit the binding of 125I-IL-3 to the high affinity IL-3R. These data suggest that the mAb 4G8 and 2F2 recognize different epitopes on the same Ag, and suggest furthermore that the inhibition of IL-3-dependent proliferation mediated by 2F2, in particular, does not occur via inhibition of ligand binding. Neither antibody showed an enhanced level of fluorescent staining of Cos 7 cells transfected with the low affinity IL-3R cDNA. In addition, 4G8 did not inhibit IL-3 binding to L cells transfected with the cloned IL-3R or IL-4R despite the fact that 4G8 was expressed on these cells. These data suggest that the 4G8/2F2 Ag is a unique cell surface protein that can interact with the endogenous functional IL-3R.

Animals↗
PubMed1990

Shared molecular markers of genetic predisposition to seropositive rheumatoid arthritis.

Rheumatoid arthritis is associated with the human class II major histocompatibility complex antigens known as HLA-DR4. HLA-DR4 can be subdivided by cellular typing into five subtypes: Dw4, Dw10, Dw13, Dw14, and Dw15. By traditional serologic methods, 60-80% of rheumatoid arthritis patients type HLA-DR4 compared to approximately 20% of the general population. It has been demonstrated, using a panel of four alloreactive T-cell clones, each of which recognized HLA-DR4, Dw14 homozygous typing cells, that cells from all of a group of 23 rheumatoid arthritis patients could be recognized by one or more of these clones regardless of the patients' serologic typing. As the expressed polymorphism of the DR molecule is accounted for by the beta 1 gene, this gene was amplified, using the polymerase chain reaction, and sequenced. Seven patients whose cells were recognized by one of the DR4, DW14-specific T-cell clones, T431, were analyzed. All of these patients shared a common sequence in the third hypervariable region of the DR beta 1 chain gene. The sequence identified is the one normally associated with DR4, Dw14 and DR1. Patients and DR4-positive controls whose cells did not stimulate this clone did not share this sequence. These results suggest that this hypervariable region might be an important contribution to a restriction site for the putative causative agent(s) in rheumatoid arthritis.

Amino Acid Sequence↗
PubMed1989

Use of 8-methoxypsoralen and long-wavelength ultraviolet radiation for decontamination of platelet concentrates.

Transmission of viral diseases through blood products remains an unsolved problem in transfusion medicine. We have developed a psoralen photochemical system for decontamination of platelet concentrates in which platelets are treated with long wavelength ultraviolet radiation (UVA, 320-400 nm) in the presence of 8-methoxypsoralen (8-MOP). Bacteria, RNA viruses, and DNA viruses ranging in genome size from 1.2 x 10(6) daltons, encompassing the size range of human pathogens, were inoculated into platelet concentrates and subjected to treatment. This system inactivated 25 to 30 logs/h of bacteria Escherichia coli or Staphylococcus aureus, 6 logs/h of bacteriophage fd, 0.9 log/h of bacteriophage R17 and 1.1 logs/h of feline leukemia virus (FeLV) in platelet concentrates maintained in standard storage bags. Platelet integrity and in vitro function before, immediately following photochemical treatment, and during prolonged storage after treatment, were evaluated by measuring: (1) extracellular pH; (2) platelet yields; (3) extracellular lactate dehydrogenase (LDH) levels; (4) platelet morphology; (5) platelet aggregation responsiveness; (6) thromboxane beta-2 (TXB-2) production; (7) dense body secretion; and (8) alpha granule secretion. These assays demonstrated that this photochemical inactivation system inactivated bacteria and viruses in platelet concentrates with minimal adverse effects on the in vitro function of platelets in comparison to untreated control concentrates maintained under current, standard blood bank conditions.

Blood Platelets↗
PubMed1988

A new look at the shared epitope hypothesis.

The striking correlation observed between T cell recognition and the sharing of the DR-beta-1 gene sequences (position 67-74) among patients with rheumatoid arthritis studied suggests that the third hypervariable region might be an important contribution to one restriction site for the putative causative agent(s) in rheumatoid arthritis. The fact that this sequence was found in DR1, DR4,Dw14, and DR4,Dw15 beta-1 genes lends support to the hypothesis that, in some cases, human leukocyte antigen and disease association may involve the association of discrete disease-related epitopes rather than entire human leukocyte antigen genes and that these epitopes are immunologically relevant in terms of T cell recognition. The association of these polymorphisms with susceptibility to rheumatoid arthritis would then support the hypothesis that binding and presentation of "arthritogenic peptides" by major histocompatibility complex class II molecules is one of the pathogenic events in developing rheumatoid arthritis.

Animals↗
PubMed1988

Aspartic acid at position 57 of the HLA-DQ beta chain protects against type I diabetes: a family study.

One hundred seventy-two members from 27 randomly selected multiple case Caucasian families of patients with insulin-dependent diabetes mellitus (IDDM) were studied at the DNA level to ascertain the reliability of codon 57 of the HLA-DQ beta-chain gene as a disease protection/susceptibility marker. The analysis was carried out by polymerase chain reaction amplification of DNA encoding the first domain of the DQ beta chain and by dot blot analysis of the amplified material with allele-specific oligonucleotide probes. One hundred twenty-three randomly selected healthy Caucasian donors were also tested. The results demonstrated that haplotypes carrying an aspartic acid in position 57 (Asp-57) of their DQ beta chain were significantly increased in frequency among nondiabetic haplotypes (23/38), while non-Asp-57 haplotypes were significantly increased in frequency among diabetic haplotypes (65/69). Ninety-six percent of the diabetic probands in our study were homozygous non-Asp/non-Asp as compared to 19.5% of healthy unrelated controls. This conferred a relative risk of 107 (chi 2 = 54.97; P = 0.00003) for non-Asp-57 homozygous individuals. Even though the inheritance and genetic features of IDDM are complex and are not necessarily fully explained by DQ beta chain polymorphism, this approach is much more sensitive than HLA serolog in assessing risk for IDDM.

Aspartic Acid↗
PubMed1987

Correlation of T cell receptor V beta gene family with MHC restriction.

We have studied a panel of DBA/2 T cell clones specific for sperm whale myoglobin (SpW Mb) for TCR (T cell receptor) beta chain gene expression by FACS analysis using the monoclonal antibodies F23.1 and KJ16 specific for the V beta 8 family of the TCR beta chain genes. Within any given specificity group, all the clones tested came from different mice. 10 of 11 I-Ed-restricted SpW Mb-specific T cell clones were F23.1+; 8 of these were also KJ16+. Only one of the three I-Ad-restricted clones tested was F23.1+; this clone was KJ16 negative. This study has demonstrated that I-Ed-restricted T cell clones from DBA/2 mice express members of the TCR V beta 8 family irrespective of the epitopes of SpW Mb recognized. These data suggest an apparent correlation between TCR V beta expression and MHC restriction.

Animals↗
PubMed1986

Interferon-gamma-induced IA expression in WEHI-3 cells is enhanced by the presence of 1,25-dihydroxyvitamin D3.

It has been suggested recently that 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] is involved in the regulation of the immune functions of lymphocytes and in the differentiation of monocytic cells. This report examined the possibility that 1,25(OH)2D3 influences immune functions mediated by monocytic cells by studying its effect on the murine myelomonocytic line WEHI-3. We found that WEHI-3 cells possess 3.3S receptor proteins with high affinity (Kd = 3.3 X 10(-10) M) for 1,25(OH)2D3 that are capable of binding to DNA. Also we found that 1,25(OH)2D3 enhances the interferon-gamma (IFN-gamma)-induced expression of the class II major histocompatibility complex antigens (Ia molecules), and such enhancement leads to increased capacity of the WEHI-3 cells to stimulate antigen-specific Ia-restricted T cell activation. Finally, 1,25(OH)2D3 inhibits the proliferation of WEHI-3 cells, and this inhibition is enhanced in the presence of IFN-gamma. The 1,25(OH)2D3 modulation of IFN-gamma induction of Ia antigens suggests that the hormone might promote monocytes to function more efficiently as antigen-presenting cells.

Animals↗