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T F Schulz

Publications and source records attributed to T F Schulz.

At least 91 records · Page 5Linked to original sources
PubMed1992

Direct demonstration of binding of aggregated mouse IgG1 to the 40-kDa Fc receptor for IgG (Fc gamma RII) in both high and low responders.

Several directly fluorochrome-conjugated murine monoclonal antibodies (mAb) of the IgG1 subclass and directed against B or T cell antigens were found to bind to monocytes via the 40-kDa Fc receptor for IgG (Fc gamma RII). As expected from the established polymorphism of Fc gamma RII, strong staining was observed in about 75% of individuals. In the remaining 25% staining was clearly weaker, but could be definitely demonstrated with a mAb against the B cell-specific CD19 differentiation antigen. Specificity of binding to Fc gamma RII was confirmed by the ability to block the binding of the CD19 mAb by pre-incubation with aggregated IgG1 or with mAb against Fc gamma RII. The extent of T cell proliferation induced with a CD3 mAb of the IgG1 isotype (a-Leu 4), which is dependent on the interaction of monocyte Fc gamma RII with the Fc portion of the CD3 mAb, exactly correlated with the amount of binding to Fc gamma RII in all individuals. Proliferation was dose-dependent for both high and low responders; cells of low responders did not proliferate at concentrations below 16 ng/ml of mAb, whereas there was a small but unequivocal proliferation at higher concentrations. These results confirm that monocytes from previously characterized "non-responders" are able to bind aggregated murine IgG1 via Fc gamma RII. They also demonstrate that directly labeled mAb can cause extensive nonspecific staining which may not be excluded by the use of control antibodies of the same isotype.

Animals↗
PubMed1992

Species specific monoclonal antibodies to Bacteroides fragilis lipopolysaccharide protect mice from severe infection.

Four monoclonal antibodies which reacted in a species specific manner with Bacteroides fragilis were isolated. They recognised at least two different epitopes of B. fragilis lipopolysaccharide. The monoclonal antibodies protected non-immune mice from longlasting bacteraemia and abscess formation induced by the intraperitoneal administration of B. fragilis in combination with an infection-potentiating agent. The monoclonal antibodies were as efficient as an anti-B. fragilis hyperimmune serum. Only antibodies administered intraperitoneally or intramuscularly were protective.

Animals↗
PubMed1992

Conserved structural features in the interaction between retroviral surface and transmembrane glycoproteins?

Among the retroviruses, the surface (SU) and transmembrane (TM) glycoproteins of lentiviruses are linked exclusively by noncovalent bonds. For some C-type retroviruses, however, a small proportion of the SU proteins has been shown to be linked to their TM proteins by a disulfide bond, with the remainder being noncovalently associated. A region near the carboxyl terminus of the HIV-1 SU glycoprotein has been implicated in contacting the TM glycoprotein. Computer modelling indicates that this region of divergent lentivirus and oncovirus SU glycoproteins forms a structurally conserved "pocket" which could accommodate a "knob"-like protrusion formed by an immunodominant region in the TM protein containing the CxxxxxC (lentiviruses) or CxxxxxxCC (C- and D-type viruses) motif. An anti-idiotypic monoclonal antibody, raised against a monoclonal antibody reacting with a sequence in the "pocket" of HIV-1 gp120, was found to bind to synthetic peptides close to the CxxxxxC motif. It is suggested that part of the SU-TM linkage mechanism for the lentiviruses and oncoviruses is a 'knob and socket' structure and that the interaction between SU and TM proteins is similar in one region for lentiviruses and C-type as well as D-type viruses. The conserved knob and socket linkage may be relevant to a mechanism for viral-cell membrane fusion that is broadly common to all of these retroviruses.

Amino Acid Sequence↗
PubMed1992

HIV-1 gp41 contains two sites for interaction with several proteins on the helper T-lymphoid cell line, H9.

OBJECTIVE: To characterize putative binding sites for HIV-1 gp41 to H9 cells. DESIGN: Based on accumulating evidence in the literature that HIV-1 can bind to cell surfaces independent of CD4, we attempted to clarify whether gp41, the transmembrane HIV-1 protein, contributes to CD4-independent binding. We therefore tested binding of gp41 to cells. METHODS: Using fluorescence-activated cell-sorter analysis, we examined the binding of recombinant gp160 (gp160) and soluble gp41 (sgp41; Env amino acids 539-684) to H9 cells, and located the putative binding site(s) of gp41 by inhibition using 16 HIV-1 Env peptides. Putative HIV-1 receptor proteins in H9 cell lysates were Western blotted and precipitated using sgp41. RESULTS: sgp41 bound to the CD4+ H9 cells and rgp160 bound to H9 cells independent of gp120-binding sites on CD4 molecules. Two gp41 peptides (Env amino acids 591-605 and 651-665) inhibited the binding of sgp41 to H9 cells. Four bands, of 37, 40, 55 and 97 kD, were blotted in H9 cell lysates, and three bands, 40, 97 and 108 kD, were observed in the precipitation analysis using lysates of 125I-surface-labelled H9 cells and sgp41 attached to sepharose beads. CONCLUSIONS: HIV-1 gp41 contains two putative binding sites to H9 cells. These sites may be located within Env amino acids 591-605 (ERYLKDQQLLGIWGC) and 651-665 (TLLEESQNQQEKNEQ). Using two different techniques, five proteins (37, 40, 55, 97 and 108 kD) were identified in H9 lysates as possible candidates for gp41 binding.

Amino Acid Sequence↗
PubMed1992

A measles virus isolate from a child with Kawasaki disease: sequence comparison with contemporaneous isolates from 'classical' cases.

We examined the relationship between a measles virus isolate from a child with Kawasaki disease and two contemporaneous wild-type isolates from children with 'classical' measles and the Schwarz vaccine strain. Sequence analysis of 3118 bp from the nucleoprotein, matrix, fusion and haemagglutinin genes of each virus revealed that the isolate from the child with Kawasaki disease was not related to measles vaccine strains and did not contain any of the marked abnormalities previously found in subacute sclerosing panencephalitis isolates, but was more akin to wild-type isolates currently circulating in the U.K. A comparison of our sequences with those obtained from earlier wild-type U.K. isolates suggests significant evolution of measles virus in the U.K. over the last decade.

Amino Acid Sequence↗
PubMed1991

A murine cell line producing HTLV-I pseudotype virions carrying a selectable marker gene.

A murine cell line, EH, expressing the gag and pol proteins of Moloney murine leukemia virus (Mo-MLV) as well as an Mo-MLV recombinant genome with a selectable marker (histidinol dehydrogenase), was transfected with a plasmid coding for the gene of the human T-cell leukemia virus type I (HTLV-I) envelope precursor (gp62), placed under the control of the human cytomegalovirus immediate early promoter. One clone, T. 14, was recovered, in which gp62 RNA and protein were detected. Supernatant from this clone transferred the HisD gene to a panel of cell lines which express receptors for HTLV-I, but was unable to pass the marker gene to cells which do not express receptors. The colony-forming units were sensitive to HTLV-I receptor interference and to specific neutralization by anti-HTLV-I serum. These data show that hybrid virions were produced in which the envelope proteins of HTLV-I had pseudotyped Mo-MLV capside particles containing a selectable recombinant viral genome.

Animals↗
PubMed1991

HTLV-1 envelope sequences from Brazil, the Caribbean, and Romania: clustering of sequences according to geographic origin and variability in an antibody epitope.

We sequenced the envelope genes of Human T-cell leukemia type I viruses (HTLV-I) derived from five Brazilian, two Caribbean, and one Romanian case of adult T-cell leukemia after amplification of the complete env gene by PCR. A comparison with previously reported HTLV-I sequences revealed that, although highly homologous, no two env sequences were identical. All envelope sequences differed from each other by 0.3-2.1% nucleotide differences. The five Brazilian sequences clustered together and were about as different from each other (0.5-0.75% nucleotide difference) as were three previously reported Japanese sequences (0.7-0.95%). In contrast, sequences of Caribbean origin were less homogeneous (0.5-1.9% nucleotide differences within this group). The Romanian sequence was not significantly more divergent than any of the others and was closest to our two Caribbean sequences. We observed two changes in a region (aa 176-209) which has previously been shown to contain a linear antibody epitope recognized by most human sera from seropositive individuals. One of these changes affects the binding of monoclonal antibodies to this epitope demonstrating the variability of an antibody epitope in the HTLV-I envelope.

Amino Acid Sequence↗
PubMed1991

The V3 loops of the HIV-1 and HIV-2 surface glycoproteins contain proteolytic cleavage sites: a possible function in viral fusion?

Located close to the crown of the V3 type-specific neutralization loop of the human immunodeficiency virus type 1 (HIV-1) (IIIB) SU glycoprotein gp120, are several potential sites that should be susceptible to proteolytic cleavage by enzymes of trypsinlike or chymotrypsinlike specificity, or by aspartic proteinases. The linkages potentially sensitive to chymotryptic/aspartic proteinase cleavage are retained also within the equivalent domain of HIV-2 (ROD) gp105. We show that thrombin and tryptase cleave HIV-1 gp120 specifically at the tryptic site (GPGR decreases AFVT), and that cathepsin E, an endosomal aspartic proteinase, cleaves at the chymotrypsinlike site (GPGRAF decreases VT). HIV-2 gp105 is also cut by cathepsin E at a site (QIML decreases MSGH) in its V3 loop. Cleavage of HIV-1 gp120 by thrombin is enhanced by sCD4 binding, but is prevented by transient exposure of gp120 to nonionic detergent. Thrombin treatment of HIV-1 gp120 destroys the binding sites for some neutralizing monoclonal antibodies (MAbs) on the V3 loop, but does not affect the affinity of gp120 for sCD4. Conversely, binding of neutralizing MAbs to the HIV-1 V3 loop prior to addition of thrombin or cathepsin E blocks the cleavage reactions, and the binding of some HIV-positive sera to gp120 blocks thrombin cleavage. Analysis of published sequences suggests that all HIV-1, HIV-2, and simian immunovirus (SIV) isolates contain potential proteolytic cleavage sites at similar positions in their V3 loops or equivalent domains. We suggest that cleavage of the V3 loop by a cell surface or endosomal proteinase occurs during the HIV-cell fusion reaction, and that neutralizing antibodies directed against the V3 loop might act by inhibition of this reaction.

Amino Acid Sequence↗
PubMed1991

Human monoclonal antibodies neutralizing cytomegalovirus (CMV) for prophylaxis of CMV disease: report of a phase I trial in bone marrow transplant recipients.

The safety and pharmacokinetics of the two neutralizing human IgG1 monoclonal antibodies to cytomegalovirus (CMV) SDZ 89-104 and 89-109 in bone marrow transplant (BMT) recipients was assessed in an open phase I trial. Thirteen patients, 8 seropositive and 5 seronegative for CMV, were treated with allogeneic or autologous bone marrow transplantation. SDZ 89-104 was given to 5 and SDZ 89-109 to 8 patients. Patients were divided into high- and low-dose groups. A fixed prestudy dose of 0.1 mg/kg was given 4 days before BMT. On days 3, 17, 31, 45, 59, and 73, patients were treated with either 0.5 or 2 mg/kg of the respective antibody. Results indicate that doses of 2 mg/kg of SDZ 89-104 or SDZ 89-109 in alternating weeks can be safely administered to BMT patients. Serum trough levels measured by antiidiotype ELISA were approximately 10 micrograms/ml after administration of 0.5 mg/kg and approximately 50 micrograms/ml after treatment with 2 mg/kg of SDZ 89-104 or SDZ 89-109. High serum levels defined by antiidiotype ELISA techniques closely paralleled increased neutralizing activity. Serum half-lives calculated from these data were approximately 6 days.

Adolescent↗
PubMed1990

Adult T-cell leukaemia/lymphoma in Brazil and its relation to HTLV-I.

In a series of fourteen patients with adult T-cell lymphoma-leukaemia (ATLL) in Brazil the main features were lymphadenopathy, hepatosplenomegaly, hypercalcaemia, and high leucocyte counts, with abnormal lymphoid cells which had irregular nuclei. The series included the youngest patient with ATLL so far (18 months). Analysis with monoclonal antibodies showed a mature T-cell phenotype (CD4+, CD8-). Antibodies to HTLV-I and/or integration of HTLV-I proviral DNA were found in eleven patients. In the other three HTLV-I DNA could not be demonstrated even by means of the polymerase chain reaction; they therefore had HTLV-I-negative ATLL. This report of ATLL in Brazil corroborates serological reports that HTLV-I may be endemic in some parts of that country. Follow-up studies are required to identify precisely the main route of transmission of HTLV-I in South America and the risk factors for the development of ATLL in carriers.

Adult↗
PubMed1990

Characterization of monoclonal antibodies to human immunodeficiency virus type 1 gp41 by HIV-1 polypeptides expressed in Escherichia coli.

Two monoclonal antibodies (MAbs) were produced in Balb/c mice by immunization with recombinant gp41 derived from expression of lambda-BH10 cDNA of the human immunodeficiency virus-1 (HIV-1) in the prokaryotic expression vector pEX-41. Characterization of the epitopes recognized by these MAbs was done with HIV-1 envelope (env) fusion proteins expressed in Escherichia coli encoding ten distinct segments of the env proteins. In comparison, another mouse MAb, M25, a human MAb directed against gp41, which was produced by the xeno hybridoma line 3D6 and a pool of human patient sera containing antibodies to HIV-1 were tested. We were able to demonstrate that the epitopes recognized by our MAbs are located between arg732 and ser759 of the HIV-1 env glycoprotein gp160 of HTLV-III strain B. M25 reacted with epitopes between ser647 and pro731, which includes the hydrophobic transmembrane region of gp41. The human MAb against gp41, 3D6 reacts with epitopes between ile474 and trp646, a polypeptide stretch consisting of gp120 and gp41 specific amino acids. The human serum pool, positive for HIV-1 antibodies, reacted predominantly with antigenic determinants located between ile474 and leu863. The recombinant env fusion proteins were initially produced to test the immunoreactivity with patient sera and to characterize epitopes which are relevant for immunodiagnostic purposes. In this study, we showed that the set of recombinant env proteins is also a simple and accurate tool for the characterization of MAbs directed to the HIV envelope proteins.

Animals↗
PubMed1990

Biological and molecular variability of human immunodeficiency virus type 2 isolates from The Gambia.

Seven new human immunodeficiency virus type 2 (HIV-2) isolates (CBL-20 to CBL-26) from The Gambia were characterized. Their cytopathogenicity and growth in vitro correlated with the severity of clinical disease. CBL-22 was highly sensitive to neutralization by HIV-2 sera and was cross-neutralized by some HIV-1 sera. These findings, the differing sizes of envelope glycoproteins of individual isolates, and the sequence analysis of amplified regions of the viral DNAs show that these HIV-2 isolates from one geographical region in West Africa exhibit biological and genome variability comparable to that observed for HIV-1.

Adult↗
PubMed1990

Expression of the C3d/EBV receptor and of other cell membrane surface markers is altered upon HIV-1 infection of myeloid, T, and B cells.

Human cell lines (the T-cell lines H9, Jurkat, and HUT102, the myeloid lines U937 and HL60, and the Raji B cell line) were infected with HIV-1. HIV-1 antigen could be detected by immunofluorescence analysis in more than 50% of T cells and myeloid cells 15 days after infection. Infection of Raji cells took more than 2-3 months. Studies of cell surface marker expression revealed remarkable changes after HIV-1 infection of Raji cells: expression of CR2 (C3d/EBV receptor, CD19, CD20, CD22, CD23, CD10, and surface IgM) were highly reduced, in the case of CR2 and membrane-IgM from 100 to 0%, whereas levels of CD37 and CD38 remained unaltered by HIV-1 infection. U937 cells showed a reduction of CD4 expression from 14 to 5% after HIV-1 infection; the CR3 expression slightly increased from 25 to 30%. In contrast, HLA-DR was only expressed (21%) after HIV-1 infection but not in uninfected U937 cells. Expression of HLA-DR could be detected also in HL60 cells (33%) after HIV-1 infection. In H9 cells, CD4 was reduced from 60 to 30% after HIV-1 infection, whereas HLA-DR and CD25/IL-2 receptor expression increased from 16 to 90% and from 0 to 50%, respectively. CD4 was reduced from 70 to 0% from Jurkat cells after HIV-1 infection, whereas expression of CR2 was only slightly diminished from 8 to 4%. Expression of CR1 and HLA-DR was slightly increased in these cells (1 to 3%).(ABSTRACT TRUNCATED AT 250 WORDS)

Antigens, Differentiation, B-Lymphocyte↗
PubMed1990

[Human immunodeficiency virus (HIV): a review].

Since its discovery in 1983, a lot of knowledge about the human immunodeficiency virus (HIV) has been accumulated. Our paper gives a brief survey on what is known at present about the structure, molecular biology, and the cell tropism of this virus. We discuss its relationship to other lentiviruses as well as its possible origin; in addition, we refer to the immune response to HIV and its interactions with the infected host. We also briefly summarize the difficulties encountered in the attempts to produce a vaccine against HIV and highlight some promising approaches in the development of such a vaccine.

DNA Replication↗
PubMed1989

Expression of 7F7-antigen, a human adhesion molecule identical to intercellular adhesion molecule-1 (ICAM-1) in human carcinomas and their stromal fibroblasts.

The 7F7-antigen is a widespread 85-kDa membrane adherence molecule involved in heterotypic adhesion between PHA-blasts and fibroblasts. Immunofluorescence analysis of COS cells transfected with clone pICAM-I indicated that 7F7-antigen is identical with ICAM-I, the ligand for the contact molecule LFA-I. We have investigated the expression of ICAM-I on several human carcinomas. Tumor cells in most carcinomas, with the exception of squamous-cell carcinomas, expressed very little ICAM-I or none at all. In contrast, marked expression of this molecule was observed on fibrous tissue in the vicinity of carcinoma cells, its intensity correlating with lymphatic infiltration in these tumors. We also examined the expression of ICAM-I on carcinoma cell lines and its induction by treatment with interferon-gamma (IFN-gamma). The inducibility of ICAM-I expression on cultured fibroblasts by several lymphokines suggests that the expression of ICAM-I in the vicinity of carcinoma cells is effected by lymphokines produced by activated lymphocytes/macrophages within the tumor.

Antigens, Surface↗
PubMed1989

Origin of HIV.

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Acquired Immunodeficiency Syndrome↗