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Results for “Thymic Factor, Circulating”

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At least 19 recordsLinked to original sources
PubMed1979

Neonatal thymus grafts. I. Studies on the regulation of the level of circulating thymic factor (FTS).

The level of circulating thymic factor (FTS) tested by its action on spleen rosette-forming cells from adult thymectomized mice, has been shown to be stable in young animals. This stability suggests a regulatory mechanism. An approach of this regulation has been attempted by disrupting the FTS level either by neonatal thymus grafting in adult normal and thymectomized animals, or by injections of synthetic thymic factor into normal, thymectomized mice, grafted or ungrafted. In all cases, after an initial increase over the normal value, FTS levels returned close to the previous range, indicating the existence of some homeostatic mechanism of FTS secretion.

Animals↗
PubMed1977

Structural study of circulating thymic factor: a peptide isolated from pig serum. II. Amino acid sequence.

The amino acid sequence of a circulating thymic factor (FTS, facteur thymique sérique) isolated from pig serum has been established as less than Glu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn-OH. This sequence was obtained by Edman analysis both on the intact peptide and after tryptic digestion. The COOH-terminal residue was identified by carboxypeptidase A digestion. A synthetic peptide was prepared which showed the same biological activities as native pig circulating thymic factor, thus confirming the proposed primary structure.

Amino Acid Sequence↗
PubMed1976

Thymic function in NZB mice. II. Regulatory influence of a circulating thymic factor on antibody production against polyvinylpyrrolidone in NZB mice.

Administration of a circulating thymic factor isolated from normal pig blood prevented the development of the exaggerated production of anti-polyvinyl pyrrolidone (PVP) antibody in young NZB mice. However, treatment was ineffective if initiated after the 4th week of life at a time when endogenous serum thymic factor (TF) normally disappears in these mice. These data suggest that circulating TF is necessary for the survival of short-lived suppressor T cells normally implicated in the regulation of the production of antibodies against PVP, a thymus-independent antigen. In older NZB mice, TF treatment increased paradoxically anti-PVP antibody production, which suggests that "amplifier" T cell activity could also be under TF influence.

Age Factors↗
PubMed1977

Structural study of circulating thymic factor: a peptide isolated from pig serum. I. Isolation and purification.

A circulating thymic factor (FTS) has been characterized by a bioassay based on its ability to render theta-negative rosette-forming cells theta-positive and azathioprine-sensitive. FTS was sequentially purified and finally isolated from 1000 liters of pig serum by ultrafiltration, gel filtration, and ion exchange chromatography. Its amino acid composition and apparent molecular weight estimated by Sephadex G-25 chromatography, indicate that FTS is a nonapeptide of composition lysine, aspartic acid (or asparagine), serine 2, glutamic acid (or glutamine) 2, glycine 2, and alanine.

Amino Acids↗
PubMed1980

Effect of long-term treatment with circulating thymic factor on murine lupus.

Mice from three different strains (NZB, B/W, and Swan) which spontaneously develop a lupus-like disease and show a premature decline of their secretion of the circulating thymic factor, Facteur Thymique Sérique (FTS), were treated repeatedly with FTS and followed for the evolution of their autoimmune disease. The autoimmune sialoadenoitis (Sjögren's syndrome) appearing in NZB and B/W mice, evaluated here by a scintigraphic method, was completely prevented or even cured by FTS treatment. The increase in anti-erythrocyte autoantibody production was transiently delayed in aged NZB mice. Conversely, antiDNA antibody production either remained unaffected or was accelerated (in B/W mice) by FTS treatment. These results demonstrate that the restoration of the failing thymic secretion does influence autoantibody production, in a manner depending primarily on the autoantigen eliciting the autoimmune response. However, caution is urged in the application of this approach to human lupus without further studies.

Age Factors↗
PubMed1976

Effects of antithymic reticuloepithelial cells serum on the levels of circulating thymic factor and on the sensitivity to azathioprine of spleen spontaneous rosette-forming cells.

Swiss mice treated with an antithymic reticuloepithelial cells serum (ATRES) showed a drastic and prolonged depression of the serum thymic factor. A similar but less pronounced effect was also observed following the administration of the antithymocyte (ATS) and the antilymphocyte (ALS) sera. Conversely, the azathioprine sensitivity of spleen spontaneous rosette-forming cells was highly modified by the ATRES but not by the ATS or the ALS. The probable mechanisms of such effects are discussed.

Animals↗
PubMed1976

[Biochemical characterization of a circulating thymic factor].

A serum thymic factor has been isolated from pig serum. Its amino-acid sequence has been determined by Edman technique, modified by Gray: Gln-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn. A nonapeptide, synthesized on the basis of this sequence is active in the rosette assay used for the isolation of the biological product, both in vitro (10(-15) M) and in vivo (0.1 ng per Mouse).

Amino Acid Sequence↗
PubMed1980

Clinical and laboratory features of canine lupus syndromes.

Determination of the specificities of antinuclear antibodies in the sera of 20 dogs presenting with symptoms of a lupus-like syndrome permitted their separation into 2 groups. The first group of 14 dogs all had antibody activity to DNA-histone antigen(s), and 4 of them also had antibodies to native DNA (nDNA). The Farr test with standard buffer was found to be unsatisfactory for the measurement of anti-nDNA antibodies in dog sera due to a high incidence of false positive reactions; these could be eliminated by the inclusion of sodium dodecyl sulfate in the buffer system. The second group of 6 dogs was characterized by the presence of antibodies to extractable nuclear antigen. In every serum tested diseased dogs had a diminished level of circulating thymic factor as compared to controls of the same age, suggesting that a diminution of suppressor T cells may be an etiologic factor.

Animals↗
PubMed1980

Synthesis of analogs of the serum thymic nonapeptide, "facteur thymique serique" (FTS). Part II.

New analogs of FTS (Facteur Thymique Sérique), less than (Formula: see text), a circulating thymic factor, were prepared by replacing the amino acid residues in positions, 1, 3, 4, 5, 6 and 3 and 6 together. Five other analogs of C-terminal heptapeptide were prepared by replacing the amino acid residues in position 3 or 6. These peptides were synthesized using conventional synthesis in solution.

Amino Acid Sequence↗
PubMed1981

Thymoma with hypersecretion of thymic hormone.

A 78-yr-old patient presented with a malignant thymoma with a predominance of epithelial cells. Lymphocyte markers (E rosettes, T-cell-specific xenoantigen and surface Ig) and electrophoretic studies showed that more than 95% of the peripheral blood lymphocytes were T cells. High levels of circulating thymic factor were repeatedly found before treatment (irradiation and chemotherapy). It is suggested that inappropriate hypersecretion of thymic hormone is responsible or can contribute to the immunological abnormalities found in this patient.

Aged↗
PubMed1980

Characterization of facteur thymique sérique (FTS) in the thymus. II. Direct demonstration of the presence of FTS in thymosin fraction V.

Thymosin fraction V was submitted to the same purification procedure as used for the isolation of the circulating thymic factor (FTS) from pig serum: an FTS-like material was isolated from this fraction and shown to have similar activity, molecular weight, charge and amino acid composition as FTS. These data, together with previous experiments showing the binding of anti-FTS antibodies to reticulo-epithelial cells, provide a direct argument in favour of the presence of FTS in the thymus.

Amino Acids↗