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Biomedical subjects

M J Caulfield

Publications and source records attributed to M J Caulfield.

At least 37 records · Page 2Linked to original sources
PubMed1997

The atrial natriuretic peptide gene and essential hypertension in African-Caribbeans from St Vincent and the Grenadines.

Atrial natriuretic peptide (ANP) which alters sodium balance, blood volume and vascular tone represents an important candidate for investigating the genetic basis of essential hypertension (EH). Accordingly, we have studied Bgl1 and Xho1 restriction fragment length polymorphisms (RFLPs) of the ANP gene in 147 hypertensive, 141 normotensive and 67 population-based control subjects from a homogenous population of West African origin from St Vincent and the Grenadines. We found no association of either Bgl1 and Xho1 RFLPs with EH. This study suggests that the ANP locus may not exert a major gene effect on EH amongst the black people of St Vincent and the Grenadines.

Adult↗
PubMed1997

The anti-erythrocyte autoimmune response of NZB mice. Identification of two distinct autoantigens.

With age, New Zealand black (NZB) mice spontaneously develop anti-mouse red blood cell (RBC) autoantibodies resulting in the development of autoimmune haemolytic anemia (AIHA). Previously, we characterized a panel of monoclonal autoantibodies derived from unimmunized, adult NZB mice. One of these antibodies (G8) was shown to be pathogenic, inducing AIHA in a non-autoimmune-prone mouse strain (BALB/c). Using G8, and two other antibodies from our panel, we have characterized two distinct autoantigens on the surface of mouse RBCs. The autoantigen, historically referred to as antigen X (AgX), was found to be partially hidden on the surface of the mouse RBC because glycosidase treatment or mild digestion with proteinase K resulted in increased reactivity with autoantibodies. One of the monoclonal antibodies (3H5G1) was found to immunoprecipitate a 110,000 MW protein identified as the erythrocyte anion transporter (band 3) whereas the pathogenic antibody (G8) as well as a third monoclonal antibody (2E6m) were shown to immunoprecipitate a 60,000 MW protein that was not reactive with the anti-band 3 serum. Finally, we show that the autoantigen recognized by G8 is expressed on differentiated mouse erythroleukaemia (MEL) cells. The results suggest that a protein distinct from band 3 can serve as a target for AIHA in NZB mice.

Anemia, Hemolytic, Autoimmune↗
PubMed1997

Priming of cytotoxic T lymphocytes by DNA vaccines: requirement for professional antigen presenting cells and evidence for antigen transfer from myocytes.

BACKGROUND: MHC class I molecule-restricted cytotoxic T-lymphocyte (CTL) responses are induced following either intramuscular (i.m.) injection of a DNA plasmid encoding influenza virus nucleoprotein (NP) or transplantation of myoblasts stably transfected with the NP gene, the latter indicating that synthesis of NP by myocytes in vivo is sufficient to induce CTL. The present study was designed to investigate the role of muscle cells and involvement of professional antigen-presenting cells (APCs) in priming CTL responses following DNA vaccination. MATERIALS AND METHODS: Parent-->F1 bone marrow (BM) chimeric mice were generated whose somatic cells include muscle cells bearing both parental MHC haplotypes, while their professional APCs express only the donor MHC haplotypes. RESULTS AND CONCLUSIONS: Upon injection of NP DNA, or after infection with influenza virus, CTL responses generated in the chimeras were restricted to the donor MHC haplotype. Thus cells of BM lineage were definitively shown to be responsible for priming such CTL responses after infection or DNA immunization. Moreover, expression of antigen by muscle cells in BM chimeric mice after myoblast transplantation is sufficient to induce CTL restricted only by the MHC haplotype of the donor BM. This indicates that transfer of antigen from myocytes to professional APCs can occur, thus obviating a requirement for direct transfection of BM-derived cells.

Animals↗
PubMed1996

Recipient polyclonal B cell activation and immunoglobulin production induced by priming with a retroviral superantigen.

The superantigen vSAG-7 (or MIs 1a) is a membrane glycoprotein encoded by the endogenous retrovirus mouse mammary tumor virus 7 (MMTV-7) and is highly stimulatory for V beta 6/CD4+ T cells. Priming of adult MMTV-7-negative mice with vSAG-7-expressing cells initially results in the activation of the peripheral V beta 6/CD4+ T cell compartment and is followed by T cell tolerance to the superantigen. During the course of tolerance induction the number of recipient B lymphocytes increases in the lymph nodes, but not the spleen, of vSAG-7-primed recipients. These B cells also express increased levels of class II MHC and present passively acquired superantigen. In this study we asked if these effects on the host B cell compartment are followed by the production of immunoglobulin. Priming of MMTV-7-negative BALB/c or CB.17 mice with vSAG-7-expressing cells from DBA/2 mice induced increases of both IgM and IgG2a in the serum. Use of Igh congenic CB.17 (IgMb) mice as recipients of the vSAG-7-presenting cells from DBA/2 (IgMa) donors indicated that the IgM and IgG produced were entirely of host origin. Priming with vSAG-7 also amplified (four- to fivefold) the antibody-producing cell response induced to a suboptimal dose of sheep RBC. Priming with purified B cells from vSAG-7 donors resulted in recipient V beta 6/CD4+ T cell activation and increased numbers of recipient B cells in the lymph nodes, but did not induce immunoglobulin production. In contrast, priming with purified CD8+ T cells resulted in increased quantities of serum IgM but not vSAG-7-reactive T cell activation or increased numbers of recipient B cells in the lymph nodes. These results indicate that the T cell activation and increased B cell number with upregulated class II MHC expression initially observed following vSAG-7 priming of adult MMTV-7-negative recipients are not linked to the induction of the recipient-derived immunoglobulin production.

Animals↗
PubMed1995

Absence of genetic linkage between polymorphisms of the insulin receptor gene and essential hypertension.

This study evaluated whether hypertensive siblings had excess sharing of RsaI and SstI alleles of the insulin receptor gene compared with a random population. Thirty families consisting of 60 affected individuals with established hypertension were genotyped for the RsaI and SstI restriction fragment length polymorphisms and the resulting genotype data was analysed using the affected pedigree member method of linkage analysis. The hypertensive siblings were found to have increased sharing of INSR alleles; however, this linkage could not be confirmed using a maximum LOD score method. Thus, the results from this study do not support a role for the INSR gene in the genesis of essential hypertension in the population studied.

Aged↗
PubMed1995

T-cell dependent response to immune complexes abrogates B-cell unresponsiveness to pneumococcal cell wall polysaccharide.

Although > 90% of B cells from M167 (mu, kappa) immunoglobulin transgenic (Tg) mice express surface immunoglobulin that binds phosphorylcholine (PC), we found that these mice are unresponsive to immunization with pneumococcal cell wall polysaccharide (PnC), a type II thymus-independent antigen that contains PC. However, when the PnC antigen was presented as a complex with TEPC-15 or McPC-603 antibodies (which are specific for PnC), a vigorous immune response occurred in which the Tg mice produced 10-50-fold more anti-PnC antibody than when immunized with antigen alone. Interestingly, MOPC-167, which expresses the VH and VL regions used to encode the transgene antibody, was found to be a relatively poor 'carrier' for PnC, eliciting a weak anti-PnC antibody response in M167 (mu, kappa) Tg mice. In vivo administration of anti-CD4 antibody dramatically reduced the response to TEPC-15/PnC complexes, suggesting that the response is mediated by immunoglobulin (idiotype)-dependent helper T cells. The results indicate that unresponsiveness to PnC is due not to tolerance of the transgenic B cells but rather to the lack of T-cell help resulting from T-cell tolerance to the transgene-encoded idiotype.

Animals↗
PubMed1994

Phase I trial of cisplatin, WR-2721, and the murine monoclonal antibody R24 in patients with metastatic melanoma: clinical and biologic effects.

The therapeutic and biologic effects of murine monoclonal antibodies in patients with malignancies have been widely investigated. Attempts to enhance results by combining these agents with cytotoxic drugs are now under study. A Phase I trial was performed to assess the toxicity and biologic effects of escalating doses of R24 (0-40 mg/m2/day 1-5, 8-12), an antibody that binds to the ganglioside GD3 present on melanoma cells, administered in combination with cisplatin (120 mg/m2) and WR-2721 (740 mg/m2) on day 1. Twenty-three patients with metastatic malignant melanoma were treated and are evaluable. The true maximum tolerated dose of R24 given as part of this combination was not reached. The toxicity of the regimen was moderate and included fever and urticaria, which were attributed to R24. Severe but reversible renal failure was noted in six patients in subsequent (two or more) treatment cycles, but when cisplatin was administered in 3% saline, this toxicity was not seen. Responses were seen in 2 of 19 patients receiving all three agents and in 1 of 4 patients receiving only cisplatin and WR-2721. No significant enhancement of natural killer, lymphokine-activated killer, and antibody-dependent cellular cytotoxicity lytic activity or significant changes from baseline in lymphocyte subsets secondary to R24 were seen. In 4 of 10 patients tumor localization of mouse monoclonal antibody was found and appeared greatest at higher R24 doses and during week 1 of therapy. Human anti-mouse antibody responses developed by day 22 in 17 of 19 patients treated with R24, and the coadministration of cisplatin did not appear to abrogate this response. Finally, the half-life and Cmax of cisplatin were not affected by R24. In summary, the combination was well tolerated, responses were few, and significant biologic interactions or immunomodulation were not observed.

Adult↗
PubMed1993

Athymic (nude) mice fail to delete functional self-reactive helper T cells.

We have examined the thymic requirement for the antibody response to a foreign antigen coupled to self erythrocytes. We find that self erythrocytes mediate thymus-independent, carrier specific help for the antibody response to the pneumococcal cell wall polysaccharide antigen, PnC. Thus, athymic nude mice gave a high primary antibody plaque-forming cell (PFC) response to PnC-mouse RBC but a low response to PnC coupled to sheep or burro RBC. The meager response to PnC coupled to foreign RBCs could not be attributed to antigenic competition since the response to the carrier (burro RBC) was < 100 PFC per spleen. Reconstitution of nude mice with splenic T cells from euthymic mice enhanced rather than suppressed the antibody response to PnC-mouse RBC. The results document that in the absence of thymic deletion, functional self-reactive helper cells persist in the nude mouse.

Animals↗
PubMed1992

Expression and regulation of a recurrent anti-erythrocyte autoantibody idiotype in spleen cells from neonatal and adult BALB/c mice.

BALB/c spleen cells depleted of CD8+ T cells generate an autoantibody response to mouse RBC (MRBC) when cultured 5 days in the presence of syngeneic RBC. More than 80% of the cells secreting anti-MRBC antibody are blocked by an antiidiotypic mAb that recognizes the G8 Id. This G8 Id was originally identified in an autoimmune NZB mouse derived anti-MRBC mAb and later characterized as a dominant Id in NZB anti-MRBC autoantibodies. Furthermore, the CD8+ regulatory T cells that control this autoimmune response in BALB/c mice are specifically eliminated by cytotoxic treatment with the G8 mAb + C, suggesting that the regulatory cells recognize the G8 Id. Spleen cells from neonatal BALB/c mice, which lack those regulatory cells can generate an in vitro antibody response to MRBC without depletion of CD8+ cells. More than 80% of these AFC were also found to express the G8 Id. We propose that Id determinants on autoantibodies that are produced neonatally induce Id-specific regulatory cells that maintain peripheral tolerance to self-RBC throughout the life of normal animals.

Animals↗
PubMed1992

A pathogenic monoclonal antibody, G8, is characteristic of antierythrocyte autoantibodies from Coombs'-positive NZB mice.

With age, NZB mice develop anti-RBC autoantibodies resulting in the development of autoimmune hemolytic anemia. We now have evidence that this spontaneous autoantibody response consists of antibodies that are similar in specificity and Id expression to a pathogenic autoantibody (G8) that was cloned from an autoimmune NZB mouse. Similar to autoantibodies eluted from Coombs'-positive mouse E (MRBC), the G8 mAb recognizes native (unmodified) MRBC but not RBC from other species. Interestingly, G8 and four additional mAb bind with a higher titer to bromelain-treated MRBC than to native MRBC. Nucleotide sequence analysis reveals, however, that unlike "natural" antibodies that react solely with bromelain-MRBC, G8 is encoded by a J558 VH gene and a V kappa 12,13 L-chain gene. Thus G8 is clearly distinct from antibodies to bromelain-MRBC which are encoded by unrelated V genes. Instead, the sequence of the G8 VH chain was found to be nearly identical to that of an anti-DNA mAb derived from an MRL-lpr/lpr mouse. The results suggest Coombs'-positive autoantibodies from NZB mice are not derived from "natural" antibodies, but rather, consist of a restricted set of autoantibodies expressing the G8 IdX.

Animals↗
PubMed1991

Coexistence of autologous antibodies and decay-accelerating factor, an inhibitor of complement, on human renal tumor cells.

Autologous immunoglobulin was detected on the cell surface of tumor cells freshly isolated from cancerous kidneys of patients with renal cell carcinoma by flow cytometry after staining with murine anti-human IgG monoclonal antibodies. Cells isolated in parallel from macroscopically normal regions of the tumorous kidneys were not specifically stained with the anti-human IgG reagents. In further studies, tumor cells were stained with an antibody to decay-accelerating factor (DAF), a known inhibitor of complement. Flow cytometry of these cells revealed that nearly all tumor cells expressed DAF, and that the intensity of staining with the anti-DAF monoclonal antibody correlated with the staining of cells with anti-IgG. The results suggest that tumor cells coated with autologous antibody may be resistant to complement-mediated cytotoxicity in vivo through the expression of high levels of DAF.

Antibodies, Monoclonal↗
PubMed1990

Evidence for regulation of the autoimmune anti-erythrocyte response by idiotype-specific suppressor T cells in NZB mice.

The present study demonstrates that specific CD8+, CD4- suppressor T cells (Ts) actively regulate the autoimmune anti-mouse red blood cell (MRBC) antibody response in spleen cell populations of young, Coombs-negative NZB mice. These Ts appear to bind a monoclonal NZB autoantibody (G-8 mAb) to unmodified MRBC which expresses a dominant idiotype (Id) in the spontaneous anti-MRBC autoantibody response of NZB mice. Treatment of normally nonauto-responsive spleen cells from young NZB mice with the G-8 mAb + C prior to culture allows these cells to develop, in 4-5 days, an autoantibody response to MRBC. The level of response obtained after depletion of the G-8-binding cells is comparable with that obtained after generalized depletion of Ts by treatment with anti-CD8 + C, suggesting that the G-8-binding cells make up a major portion of the regulatory Ts in this response. Yet, G-8 + C treatment depletes a very small subset of cells and not the total CD8+ T cell population. The regulatory cells appear to be neither isotype nor allotype specific, nor do they appear to have MRBC antigens bound to or expressed on their membranes. Rather, these cells are more likely G-8 idiotype specific. The regulatory G-8-binding cells are CD8+ T cells, not B cells. Furthermore, Ts-enriched populations when depleted of G-8-binding cells lose their ability to suppress in vitro anti-MRBC responses of spleen cells from Coombs-negative NZB mice depleted of CD8+ cells, as well as those of unfractionated spleen cells from Coombs-positive NZB mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1990

Phase Ia-Ib trial of an anti-GD3 monoclonal antibody in combination with interferon-alpha in patients with malignant melanoma.

A phase Ia-Ib study was undertaken to treat melanoma patients with a constant dose of the anti-GD3 monoclonal antibody, R24, in combination with increasing dose levels of recombinant interferon-alpha (rHuIFN alpha-2a). Fifteen patients were treated on days 1-5 and 8-12 with a continuous 6-h i.v. infusion of R24 (8 mg/m2) and escalating i.m. doses of rHuIFN alpha-2a. Peripheral blood lymphocytes were obtained at multiple times before and during treatment and monitored for changes in lymphocyte subpopulations and changes in natural killer and antibody-dependent cellular toxicity functional activity. There were no consistent changes in most immune parameters; however, there was a decrease from pretreatment levels in the suppressor T cell (CD8+, CD11b+) subset and a dose-dependent decrease in the helper/inducer (CD4+, Leu-8+) T cell subset. The peak serum concentration of R24 was reached on day 5 of the study and was 9.4 micrograms/ml. During the second week of treatment, peak serum levels of R24 fell to less than 4 micrograms/ml. This finding was related to the development of human antimouse antibody, which would be detected as early as day 8 of the study. Binding of mouse Ig (R24) within the tumor bed was observed in 5 of 12 biopsy specimens. The maximal tolerated dose of the combination was dose level IV, in which patients received 8 mg/m2 of R24 and 50 x 10(6) units of rHuIFN alpha-2a on days 1-5 and 8-12 of treatment.

Adult↗
PubMed1989

Characterization of two cell lines with distinct phenotypes and genotypes established from a patient with renal cell carcinoma.

Two human renal carcinoma cell lines have been established from the same patient. One cell line (CCF-RC1) was obtained from the primary tumor and the second (CCF-RC2) was established from cells of the renal vein effluent of the perfused tumorous kidney. Although they were established from the same patient, the cell lines differed in certain biological properties. They have been passaged up to 50 times in vitro for about two years. Each has an epithelial morphology and exhibits mutilayering. Cell cycle time of CCF-RC1 and CCF-RC2 was 34 and 36 h, respectively. They exhibited anchorage independent growth, and the plating efficiency of CCF-RC2 in soft agar was higher than that of CCF-RC1. Both lines induced tumors in nude mice at the site of s.c. injection closely resembling the original tumor in histological examination. Electron microscopic features of both tumors in nude mice were consistent with epithelial origin. Doubling time of CCF-RC1 and CCF-RC2 in nude mice was 11 and 12 days, respectively. CCF-RC1 and CCF-RC2 have hypotetraploid karyotype and modal numbers of 83 and 73, presenting two and three marker chromosomes, respectively. Immunocytology with commercial monoclonal antibodies against renal carcinoma (URO-3) and cytokeratin (Mac 6) showed positive reactions with both lines, suggesting that these cell lines derived from renal epithelium. A murine monoclonal antibody (2E11) was generated against CCF-RC2 by the hybridoma technique; 2E11 reacted with CCF-RC2, but not with CCF-RC1. These cell lines may provide a useful model for the study of tumor heterogeneity and its relationship to metastasis.

Animals↗
PubMed1989

Characterization of the spontaneous autoimmune (anti-erythrocyte) response in NZB mice using a pathogenic monoclonal autoantibody and its anti-idiotype.

A monoclonal anti-mouse RBC antibody (G-8) has been prepared that appears to represent a pathogenic autoantibody related to those that arise spontaneously in aging NZB mice and which cause autoimmune haemolytic disease (AIHD). When G-8-producing hybridoma cells were grown as tumours in BALB/c mice, the mice developed AIHD characterized by a decrease in the number of erythrocytes (haematocrit) and the development of Coombs-positivity. An anti-idiotypic antibody (E8) was prepared against G-8 and was found to recognize an idiotypic determinant present on most autoantibody-forming cells derived from old (Coombs-positive) NZB mice. The results suggest that the IgM autoantibody response of NZB mice to self-erythrocytes is restricted to a limited number of clones, most of which express the G-8 idiotype.

Anemia, Hemolytic, Autoimmune↗