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S Faas

Publications and source records attributed to S Faas.

9 recordsLinked to original sources
PubMed2000

Evidence for superantigen involvement in preeclampsia.

PROBLEM: Preeclampsia is the leading cause of maternal morbidity and premature fetal delivery in the United States, most likely involving the immune system in disease genesis. In this report, we tested the hypothesis that a superantigen phenomenon is an important factor in the pathogenesis of the disease. METHOD OF STUDY: A semi-quantitative polymerase chain reaction (PCR) was used to assess T-cell receptor (TCR) beta chain variable (Vbeta) regions as an indicator of T-cell expansion in both peripheral blood and basal plate of preeclamptic patients. All the subjects were also molecularly typed to identify their HLA-class II alleles. RESULTS: In peripheral blood of the majority of the patients, there was a high abundance of the Vbeta4 gene family, which was not observed in the control group. Polyclonality of this Vbeta gene family was confirmed by analysis of the Valpha chain and the complementary determining region 3 (CDR3). The majority of patients carried the Human Leukocyte Antigens (HLA)-DRB1*13 allele. CONCLUSION: We present evidence for the existence of a superantigen-like effect in at least a subset of patients with preeclampsia.

Alleles↗
PubMed2000

Virus- and bradykinin-induced airway hyperresponsiveness in guinea pigs.

The involvement of bradykinin in virus-induced airway hyperresponsiveness (AHR) in guinea pig airways in vivo was determined with the B(2)-receptor antagonist Hoe 140. The efficacy of Hoe 140 treatment was assessed through its effect on the bradykinin-induced (up to 2.5 microgram/100 g B.W. administered intravenously) decrease in blood pressure (BP). Hoe 140 (0.1 micromol/kg), administered subcutaneously twice a day for 5 d almost completely blocked bradykinin-induced changes in BP. Four days after parainfluenza-3 (PI-3) virus infection, guinea pigs showed AHR; excessive airway contraction was found with histamine-receptor stimulation. This hyperresponsiveness was completely inhibited by pretreatment with Hoe 140 (0.1 micromol/kg) administered subcutaneously twice a day for five consecutive days, starting 1 d before virus inoculation. Interestingly, nebulized delivery of bradykinin itself to captopril-treated animals induced an AHR comparable to that observed in virus-treated guinea pigs. Viral infection also caused influx of bronchoalveolar cells into the lungs. Both histologic examinations and lung lavage experiments showed that this cell influx could not be inhibited by pretreatment with Hoe 140. In summary, the results of the study show that bradykinin is involved in a cascade of events leading to AHR after a viral infection in guinea pigs, without affecting bronchoalveolar cell influx.

Adrenergic beta-Antagonists↗
PubMed1996

The t(5;17) variant of acute promyelocytic leukemia expresses a nucleophosmin-retinoic acid receptor fusion.

We have studied an acute promyelocytic leukemia (APL) patient with a variant t(5;17)(q32;q12). This translocation fuses the gene for the nucleolar phosphoprotein nucleophosmin (NPM) to the retinoic acid receptor alpha (RARA). Two alternatively spliced transcripts are expressed, which differ in 129 bases immediately upstream of the RARA sequence. The NPM sequences contained in the shorter NPM-RAR cDNA are identical to the NPM sequences contained in the NPM-ALK fusion gene expressed in t(2;5) lymphomas. The RARA sequences are the same as the RARA sequences found in the PML-RAR and PLZF-RAR fusion seen in t(15;17) and t(11;17) APL, respectively. Both NPM-RAR transcripts fuse NPM and RARA sequence in the same reading frame, to generate translation products of 57 kD and 62 kD. Both NPM-RAR proteins are expressed in the patient's leukemic cells, along with wild-type RARA derived from the uninvolved allele. In transcriptional assays using a retinoic acid response element reporter construct, both NPM-RAR fusion proteins act as retinoic acid-dependent transcriptional activators. This case defines a third class of APL rearrangements, all of which generate fusion proteins of RARA.

Animals↗
PubMed1995

Genetic background and environment contribute synergistically to the onset of autoimmune diseases.

Autoimmune diseases result from the breakdown of "self" tolerance. Environmental factors appear to be responsible for triggering this errant immune response, directed against self-tissue determinants, only when a susceptible genetic background is present in an individual. Autoimmune diseases, normally characterized by their association with certain HLA alleles, also share other features: the presence of autoantibodies, autoreactive T lymphocytes, and an intermittent clinical course of exacerbations and remissions. In cases of organ-specific diseases, as well as in cases of multi-system autoimmune diseases, viruses are increasingly implicated as such environmental triggers. Current molecular biology techniques have permitted a fine dissection of the genetic background of susceptible individuals and have enabled a more complete characterization of the immunocompetent cells involved in this autoaggression. Molecular approaches will soon allow us to pinpoint the characteristics of the environmental stimuli, so that protective strategies could be formulated to spare susceptible individuals from their ill effects.

Autoimmune Diseases↗
PubMed1988

SV40 T-antigen is a histocompatibility antigen of SV40-transgenic mice.

Although the extensive family of non-H-2 histocompatibility (H) antigens provides a formidable barrier to transplantation, the origin of their encoding genes are unknown. Recent studies have demonstrated both the linkage between H genes and retroviral sequences and the ability of integrated Moloney-murine leukemia virus to encode what is operationally defined as a non-H-2 H antigen. The experiments described in this communication reveal that skin grafts from an SV40 T-antigen transgenic C57BL/6 mouse strain are rejected by coisogenic C57BL/6 recipients with a median survival time of 49 days, which is comparable to those of many previously defined non-H-2 H antigens. The specificity of this response for SV40 T-antigen was demonstrated by the identification of SV40 T-antigen-specific cytolytic T lymphocytes and antibodies in multiply-grafted recipients. Although these cytolytic T lymphocytes could detect SV40 T-antigen on syngeneic SV40-transformed fibroblasts, they neither could be stimulated by splenic lymphocytes from T-antigen transgenics nor could they lyse lymphoblast targets from T-antigen transgenics. These observations suggest a limited tissue distribution of SV40 T-antigen in these transgenics. These results confirm the role of viral genes in the determination of non-H-2 histocompatibility antigens by the strict criteria that such antigens stimulate (1) tissue graft rejection and (2) generation of cytolytic T lymphocytes. Furthermore, they suggest that the SV40 enhancer and promoter region can target expression of SV-40 T-antigen to skin cells of transgenic animals.

Animals↗
PubMed1985

A subset of Ly-1 inducer T cell clones activates B cell proliferation but directly inhibits subsequent IgG secretion.

We find that a fraction of Ly-1+2- inducer T cell clones inhibits differentiation of memory B cells into IgG-secreting plaque-forming cells. Inhibition of secondary antibody responses was not the result of induction of Ly-2+ T suppressors. Instead, inducer cells directly inactivated B cells, requiring an antigen bridge as well as identity at the major histocompatibility complex (I-A) locus. The interaction between the inducer T cell clone and hapten-specific B memory cells results in an early proliferative response and subsequent failure of B cells to secrete antibody in response to T helper cell signals. Possible mechanisms for this novel type of B cell inactivation are explored.

Animals↗
PubMed1985

Class I and class II restriction pattern polymorphisms associated with independently derived RT1 haplotypes in inbred rats.

This communication reports the DNA level identification of class I and class II sequences associated with 20 RT1 haplotypes which have been assigned previously to eight RT1 groups. Sixteen to 22 bands in genomic blots hybridized with the mouse pH-2III class I cDNA probe. Only the three RT1k haplotypes associated with identical class I restriction fragment patterns. Differences in restriction bands between putatively identical RT1 haplotypes were either less than or equal to 6%, or greater than 50%, suggesting a relatively high level of recombination between serologically identified RT1.A genes and the majority of class I sequences. Restriction fragment patterns associated with three RT1u haplotypes differed by less than 6%. However, intra-RT1a, intra-RT1b, and intra-RT1l restriction fragment differences were between 50 and 64%. In specific cases, different RT1 haplotypes associated with identical class I restriction patterns, e.g., RT1m (MNR) and RT1d (MR); higher resolution confirmed the difference (two bands) between RT1m and RT1d. Results of hybridization with the human DC1 beta probe confirmed that the AVN RT1a and NSD RT1b haplotypes were generated by recombinations within the vicinity of the RT1.B:RT1.D regions. These results demonstrate that a previous classification of RT1 haplotypes was incomplete and did not include the majority of class I and class II sequences which distinguish RT1 haplotypes.

Animals↗