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Results for “T-Lymphocytes, Helper-Inducer”

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At least 19 recordsLinked to original sources
PubMed1978

Modulation of the acquisition and expression of immunity by Tilorone: II. Humoral responsiveness.

Tilorone (2,7-bis[(diethylamino)ethoxy]fluoren-9-one) can enhance the humoral immune response of mice to SRBC although Tilorone has no effect on functional activity of splenic B cells in the absence of immunogen. Tilorone does not alter the effective level of T cell help but does seem to alter the level of effective suppression. Tilorone seems to be an adjuvant only in the sense of removing a normal homeostatic control mechanism, perhaps suppressor T cells.

Adjuvants, Immunologic↗
PubMed1977

Experimental conditions for obtaining suppressor and helper effects on the primary in vitro immune response by lymphocytes activated by polyclonal T-cell activators.

The effect of the polyclonal T-cell activators (PTA) Con A and PHA on the specific immune response to sheep red blood cells (SRC) was studied. Addition of PTA either enhanced or suppressed the anti-SRC response, and two variables were found to affect the results: time of addition of the PTA and the strength of the response in control cultures not given PTA. If the response was high, even suboptimal PTA concentrations induced suppressive effects, but if the control response was low, due to deficient batches of sera or because of the absence of serum, the addition of PTA increased the response or restored it to normal levels. Suppression could be obtained if the PTA were added before or at the same time as the antigen and required high (optimal) PTA concentrations. If addition was delayed for 12-24 h the suppressive effects disappeared and previously suppressive concentrations of the PTA now caused an enhanced response. Analogous results were obtained if preactivated lymphocytes were added to the cultures instead of soluble PTA. Neither Con A, PHA, or lymphocytes preactivated by these PTA suppressed the polyclonal response induced by LPS or PPD. Irrespective of the time of addition and the culture conditions, enhancement of the anti-SRC response occurred at lower PTA concentrations than suppression. It was concluded that suppressor T cells, if they exist, do not act on B cells, but rather on helper cells needed for induction of thymus-dependent responses. The findings in this system are not compatible with the existence of a specific subset of suppressor T cells, but rather with the notion that suppression is caused by too much help.

Animals↗
PubMed1992

Hypothesis for the control of clotting factor VIII inhibitory antibodies by decreasing potency of helper T-cell-recognized epitopes in factor VIII.

The study of the immunobiology of FVIII inhibitors may lead to new therapies for this potentially severe complication of haemophilia A and to new principles for the use of therapeutic proteins. In order to characterize the idiotype-anti-idiotype networks regulating FVIII inhibitors, we developed rabbit anti-idiotypic sera to 7 murine inhibitors and found at least 12 independent FVIII loci to which inhibitors could be raised. Rabbit antisera to the FVIII peptide, Ser1687-Thr1695, characterized one functional site to which about 46% of patients' inhibitor sera reacted. The multiplicity of inhibitor-recognized epitopes in FVIII makes it impractical, at the present time, to develop clinically useful specific anti-idiotypic therapies for FVIII inhibitors. Alternatively, one might induce genomic mutations in recombinant FVIII molecules to decrease immunogenicity of epitopes recognized by T helper cells. Methods to design such altered therapeutic proteins are presented, based on changing the longitudinal hydrophobic strip-of-helix which is in or near many T-cell-presented epitopes.

Animals↗
PubMed1992

Induction of T helper cells and cytokines for mucosal IgA responses.

CD4+ Th cells and their derived cytokines play an important role in the regulation of IgA responses in the mucosal immune system. Th1 and Th2 cells induce different Ig isotype and IgG-subclass responses. Further, cytokines produced by Th2-type cells (e.g., IL-5 and IL-6) have been shown to induce PP sIgA+ B cells to secrete IgA. Our studies have now shown that oral immunization with SRBC selectively induces Th2-type cells in PP while systemic (I.P.) immunization with SRBC predominantly induces Th1-type cells. It is tempting to suggest that Th2 cells which produce IL-5 and IL-6 tend to be predominant in mucosal effector regions, such as the salivary glands and LP tissues and account for the predominant IgA responses which characterize these tissues. The PP contain B cell subsets which respond to IL-5 and IL-6, and these are largely restricted to the PNALo non-GC (memory) sIgA+ B cells. The importance of CD4+ Th cells in the regulation of IgA responses has also been shown by the depletion of CD4+ Th cells in anti-L3T4 (CD4)-treated mice. Loss of CD4+ Th cells from mucosal tissues resulted in dramatically decreased numbers of IgA plasma cells in the small intestine and led to a reduction in IgA SFC in isolated LP cells. The overall size of PP was reduced and the GCs were absent; however, the relative frequency of sIgA+ B cells in PP did not change, possibly suggesting that CD4+ Th cells do not influence switches to IgA.

Animals↗
PubMed1992

Development and characterization of Porphyromonas gingivalis-specific rat T-cell clones.

Porphyromonas gingivalis has been implicated as a major pathogen in periodontitis. To determine the role of T cells in the regulation of this disease, a method was developed for the generation and characterization of rat T-cell clones with antigen specificity to P. gingivalis whole cells. The clones studied so far demonstrated a T-helper (Th) phenotype W3/13+, W3/25+, OX8- and OX22-. These T-cell clones proliferated in vitro in response to P. gingivalis, but not to other bacteria (Prevotella intermedia, Actinobacillus actinomycetemcomitans, Wolinella recta, Fusobacterium nucleatum, Streptococcus sanguis). Limiting dilution analysis showed W3/25+, OX8- T cells preferentially respond to P. gingivalis, rather than W3/25-, OX8+ T cells. P. gingivalis-reactive W3/25+ T cells belonged to the OX22- population, suggesting that the OX22- T cells may represent memory cells. All clones tested produced interferon gamma, but not interleukin 2. The cloned T-cell F1 significantly enhanced P. gingivalis-specific antibody production (p < 0.03). The availability of these cloned T cells should bring new insight into the mechanism by which T cells regulate oral health and periodontal disease.

Animals↗
PubMed1992

Anomalous reversed-phase high-performance liquid chromatographic behavior of synthetic peptides related to antigenic helper T cell sites.

Sets of overlapping synthetic peptides for three well characterized proteins (sperm whale myoglobin, hen egg lysozyme, and the circumsporozoite protein from Plasmodium falciparum) were prepared and examined by reversed-phase high-performance liquid chromatography (RP-HPLC). Using retention coefficients to predict the retention time of each peptide, several peptides in each protein set were found that exhibited anomalous behavior (i.e. eluted significantly later than predicted). Previous work with model peptides has shown that this anomalous behavior can be attributed to specific amphipathic arrangements induced by the lipid stationary phase during the RP-HPLC process. In the current study it was found that although not all of the peptides containing an antigenic T cell site displayed anomalously late behavior, all of the peptides which eluted anomalously late during RP-HPLC included the regions of these proteins known from earlier studies to be antigenic T cell sites.

Amino Acid Sequence↗
PubMed1992

A vaccine against Semliki Forest virus consisting of a monoclonal anti-idiotypic antibody cross-linked to a protein which contains virus-specific T-helper cell epitopes.

A recombinantly expressed protein, consisting of cro-beta-galactosidase at the N-terminus and amino acid residues 115 to 151 of the E2 membrane of Semliki Forest virus (SFV) at the C-terminus containing two T-helper cell epitopes of SFV, was cross-linked with glutaraldehyde to a noninternal image monoclonal anti-idiotypic antibody (ab2 alpha MAb) able to induce SFV-neutralizing anti-anti-idiotypic (ab3) antibodies in BALB/c mice. This vaccine, which might potentially induce SFV-specific T-helper cell memory, established in BALB/c mice a state of protective immunity against virulent SFV within 10 days of immunization. A steady rise in serum neutralization titre occurred from day 7 to day 28 after primary anti-idiotypic immunization, levelling off thereafter. In primarily immunized mice significant rises of serum neutralization titres, which could be indicative for an operational T-helper cell memory, were not observed after challenge on day 35 with virulent SFV. The results suggest that SFV is neutralized by ab3 antibodies shortly after challenge, preventing, thereby, virus multiplication to levels sufficient to provoke a measurable booster response.

Animals↗
PubMed2016

Activin A programs the differentiation of human TFH cells.

Follicular helper T cells (TFH cells) are CD4(+) T cells specialized in helping B cells and are associated both with protective antibody responses and autoimmune diseases. The promise of targeting TFH cells therapeutically has been limited by fragmentary understanding of extrinsic signals that regulate the differentiation of human TFH cells. A screen of a human protein library identified activin A as a potent regulator of TFH cell differentiation. Activin A orchestrated the expression of multiple genes associated with the TFH program, independently or in concert with additional signals. TFH cell programming by activin A was antagonized by the cytokine IL-2. Activin A's ability to drive TFH cell differentiation in vitro was conserved in non-human primates but not in mice. Finally, activin-A-induced TFH programming was dependent on signaling via SMAD2 and SMAD3 and was blocked by pharmacological inhibitors.

Activins↗
PubMed2026

TGF-&#x3b2; and IL-2 differentially shape T follicular regulatory cell differentiation and stability in vitro.

T follicular helper (Tfh) cells and T follicular regulatory (Tfr) cells play critical roles in regulating the activity of the germinal center (GC), which is essential for the generation of high-affinity antibodies. In the GC, Tfh cells help B cells to&#xa0;proliferate and to&#xa0;differentiate into memory B cells and long-lived plasma cells. In contrast, Tfr cells, a specialized subset of regulatory T cells (Tregs), modulate the humoral immune response by suppressing excessive or autoreactive B-cell activity. Here, we established an in vitro differentiation protocol for mouse CD4&#x207a; T cells that yielded CXCR5&#x207a;FoxP3&#x207a; Tfr cells that exhibited a Bcl6hiPD-1hiCD25loGITRint phenotype and were distinct from Treg and Tfh cells. Functionally, in vitro-generated Tfr cells potently suppressed Tfh cell-driven B-cell class switching to IgG1 and downregulated the expression of B-cell costimulatory ligands. While in vitro-generated Bcl6-deficient Tfh cells were impaired in providing help to B cells for efficient class switching to IgG1, in vitro-generated Bcl6-deficient Tfr cells failed to inhibit Tfh cell-driven B-cell class switching to IgG1. Mechanistically, we showed that Tfr cells emerged from FoxP3+ precursors in low-IL-2 environments through a TGF-&#x3b2;- and c-Maf-dependent pathway, allowing for reprogramming and reinforcement of the follicular regulatory cell program in CD4+ T cells in vitro.

Animals↗
PubMed1977

Generation of T-helper cells in vitro. I. Cellular and antigen requirements.

A sequential mouse cell culture system is described for the induction and assay of T-helper cells. Unprimed, cortisone-resistant, nylon wool-purified thymocytes cultured with adherent peritoneal exudate cells can be primed in vitro with soluble carrier protein to generate carrier-reactive helper cells. These cultured cells enhance the anti-hapten plaque-forming response of hapten-primed spleen cell cultures to hapten carrier conjugates. The culture conditions, cellular manipulations, and antigen requirements for the optimal induction of helper cells with these purified cell populations is presented. The active helper cell generated in this culture system is a thymus-derived cell which requires macrophages for its induction and must be proliferate in vitro before the manifestation of helper-cell function. Helper cells generated in vitro stimulate both carrier-specific and nonspecific enhancement of splenic anti-hapten responses. The carrier-specific and nonspecific enhancement can be distinguished by the requirement for antigen in the helper cell and spleen cell cultures, the dose of helper cells added to the spleen cell cultures, and by the requirement for additional splenic adherent accessory cell interactions.

Animals↗
PubMed1977

Generation of T-helper cells in vitro. II. Analysis of supernates derived from T-helper cell cultures.

Supernates derived from in vitro generated T-helper cells have been analyzed for their capacity to substitute for T-cell carrier reactivity. T-helper cell supernates stimulate both a carrier-specific and nonspecific anti-DNP-PFC response to DNP-carrier conjugates in cultures of hapten-primed spleen cells. The carrier-specific and nonspecific activity can be distinguished by dosage optimum, antigen requirements, binding specificity for carrier, and in the requirement for additional splenic adherent accessory cell involvement. The active factors produced in this system are heat labile and sensitive to trypsin and periodate. They are removed by absorption with alloantisera directed toward the strain from which the supernate was derived but not by a variety of anti-immunoglobulin sera.

Animals↗
PubMed1977

A requirement for antigen-specific helper T cells in the generation of cytotoxic T cells from thymocyte precursors.

Thymocytes cultured with irradiated, allogeneic stimulator cells yield no cytotoxic effector cells after a period in culture. If, however, a population of irradiated spleen cells syngeneic to the responder cells are added to these cultures, cytotoxicity is generated. The helper activity present in the irradiated syngeneic spleen cells was found to be mediated by a cell bearing theta antigens. Furthermore, it was found to be antigen specific; helper cells which were tolerant of the stimulator cell antigens were unable to help the thymocyte responder cells, although these tolerant cells did contain helpers specific for a third party antigen. These experiments are consistent with a requirement for associative recognition of linked determinants in the induction of killer precursors which is thus strictly analogous to the induction of B-cell precursors via collaboration with helper T cells. In more extensive studies, it was found that histoincompatible helper cells (H-2b, H-2p, H-2q) were able to help a cytotoxic T cell (H-2k) response to a third party stimulator cell antigen (H-2d); that is, the helper T cells which interact with cytotoxic T-cell precursors are not strain specific. It seems likely that the histocompatible helper cells induce killer precursors in an antigen-specific cooperation event similar or identical to normal syngeneic cooperation.

Animals↗
PubMed1992

Processing and presentation of insulin. III. Insulin degrading enzyme: a neutral metalloendoproteinase that is non-homologous to classical endoproteinases mediates the processing of insulin epitopes for helper T cells.

Presentation of a protein antigen to T cells generally requires that the antigen be enzymatically processed into an immunogenic peptide(s). The identification of a protease(s) and its mechanism of action in the proteolysis of such an antigen is therefore a primary goal in the study of antigen processing. We show here that insulin degrading enzyme (IDE), a neutral thiol metalloendoproteinase that is structurally non-homologous to the classical metallo, thiol, acid, or serine proteinases, is relatively specific in its proteolytic activity for insulin and digests human insulin (H(I)) into peptides that are presented by murine TA3 B cell antigen presenting cells (APCs) to HI/I-Ad-reactive T cells. These peptides are, however, not presented by fixed TA3 APCs. Anti-IDE mAbs, after their internalization by TA3 cells, significantly inhibit the presentation of H(I) by these APCs. Immunoblotting experiments demonstrate that this inhibition is mediated by the reactivity of these mAbs with a 110 kDa protein, the known M(r) of IDE. These data show that IDE is an endoproteinase that is involved in the processing of insulin and that this IDE-mediated proteolysis is necessary but not sufficient for the recognition of insulin by T cells. Furthermore, we demonstrate that reduction of the disulfide bonds of a pre-processed A-loop containing heterodimeric insulin peptide is required to further process insulin into a T cell epitope.

Animals↗
PubMed1992

Identification of lymphocyte subsets in the human fallopian tube.

PROBLEM: Immunohistochemical investigations for the detection of lymphocyte subsets in the human oviduct have been performed. Knowledge about local immunity especially cell-mediated immunity, in the fallopian tube has been, up to now, limited. As an essential structure for the human reproduction process, the tubal mucous membrane is exposed to a variety of antigens. METHOD: A total number of 20 tubal biopsies obtained from fertile women during gynecological operations like tubal ligations or hysterectomy were examined by the immunoperoxidase technique. Seven specimens were obtained during the proliferative phase, ten during the secretory phase and three during a caesarean section with tubal ligations. RESULTS: It could be established that the presence of lymphocytes in the oviductal mucous membrane is physiological. These cells can be identified by their typical immunohistochemical patterns. There were no significant differences of the type and number of lymphocytes in the mucosa within the phases of menstrual cycle. The dominant cell types in the tubal mucosa were the CD3+ and CD8+ lymphocytes. CONCLUSIONS: It can be suggested that the lymphocytes in the tubal mucosa may involved in the process of immune tolerance, which could realize the transport of sperms and blastocysts through the oviduct under normal conditions without activation of local immune mechanisms. The lymphoid tissue of the oviduct is a specialized form of mucosal-associated lymphoid tissue (MALT).

Adult↗