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R DeKruyff

Publications and source records attributed to R DeKruyff.

6 recordsLinked to original sources
PubMed1994

Peptides corresponding to the CD8 and CD4 binding domains of HLA molecules block T lymphocyte immune responses in vitro.

CD4 and CD8 are cell surface glycoproteins that serve as co-receptors for Ag with the TCR. Recent studies have shown that both CD4 and CD8 interact with conserved regions of MHC class II and class I, respectively. To investigate further the roles of CD4 and CD8 in the immune response, we prepared synthetic peptides corresponding to the HLA sequences with which CD4 and CD8 are thought to interact. The peptide corresponding to residues 222 to 235 of the HLA class I heavy chain blocked the differentiation of human CTL precursors into active effect cells but affected neither the ability of PBLs to proliferate in response to mitogen nor the cytotoxic activity of established CTLs. In contrast, the peptide corresponding to residues 134 to 152 of the HLA-DR beta-chain inhibited the differentiation of CTL precursors, the proliferative response of freshly isolated PBL, and the proliferation of an established alloreactive CD4+ T cell clone to Ag. The inhibitory effect of the DR.134-152 peptide on CTL differentiation could be overcome by addition of exogenous IL-2 to the limiting dilution cultures, whereas the effect of the HLA-1.222-235 peptide was unaffected by exogenous IL-2. These results directly demonstrate a functional role for these regions of MHC molecules and underscore the central role of both CD4 and CD8 in the effective initiation of a CTL response.

Base Sequence↗
PubMed1987

Cloning and characterization of a novel T cell activation gene.

We have used the technique of subtractive hybridization to identify a T cell gene selectively expressed during activation via the antigen-receptor pathway. This gene, termed TCA3 (for T cell activation) encodes a mRNA which is expressed following concanavalin A (Con A) activation of T cell clones at levels of approximately 1% total poly(A)-containing mRNA. The cDNA isolate, termed TCA3.0, is 512 bases in length excluding poly(A) and encodes a predicted 92-amino acid protein having the characteristics of a secreted polypeptide of approximately 69 amino acids. The genomic organizations of TCA3 was determined for two lambda phage clones and was found to be a single copy gene containing at least three exons dispersed over less than 4.7 kb. The temporal appearance of TCA3 mRNA in response to several activating agents was examined. It is not transcribed in response to interleukin 2 stimulation, but is transcribed in response to either antigen or Con A stimulation and can be detected as early as 1 hr poststimulation. Expression TCA3 in response to Con A is blocked by cyclosporin A treatment. The combined data suggest that TCA3 may represent a new lymphokine.

Amino Acid Sequence↗
PubMed1985

B cell activation: role of dendritic and T cell factors in the response to thymic-independent and -dependent antigens.

We described a cloned dendritic cell, clone Den-1, that is a potent accessory cell for some B cell responses. Clone Den-1 produces a novel lymphokine that is distinct from previously described factors produced by T cells. In the present study, we compare the role of nonspecific helper factors produced by Den-1 (Den-1 SN) or the T cell thymoma EL4 (EL4-SN) in promotion of B cell plaque-forming cell (PFC) responses to a variety of antigens. We find that the antigen in culture determines the B cell requirement for dendritic and/or T cell factors. B cell PFC responses to TNP-Brucella abortus (BA) and TNP-lipopolysaccharide (LPS) are greatly increased by EL4-SN but show little, if any, enhancement with Den-1 SN. Responses to TNP-polyacrylamide are reconstituted by either Den-1 SN or EL4-SN, whereas responses to TNP-Ficoll, TNP-dextran and TNP-levan are reconstituted by Den-1 SN and are much less sensitive to factors present in EL4-SN. Responses to SRBC require the presence of both Den-1 SN and EL4-SN. We also show that the time at which Den-1 SN must be provided to the B cell is dependent on the antigen in culture. Our findings are discussed in terms of present classification of antigens based on their ability to stimulate various B cell subpopulations.

Acrylic Resins↗
PubMed1985

Activation requirements of cloned inducer T cells. I. Differential inhibition by anti-L3T4 or anti-I-A is determined by the accessory cell population.

We have described a trinitrophenyl (TNP)-specific inducer clone, clone Ly-1-T1, which responds to a variety of different stimuli, including a) soluble TNP-protein conjugates plus syngeneic (H-2d) spleen cells, b) TNP directly coupled to syngeneic or allogeneic spleen cells, and c) activated I-A identical B cells in the absence of nominal antigen. In the present study we used a panel of antibodies to investigate the recognition structures involved in the activation of clone Ly-1-T1 by these different stimuli. We show that allogeneic spleen cells must be conjugated by using relatively high concentrations of TNBS to be efficient stimulators of the clone. In contrast, syngeneic spleen cells conjugated by using a much wider range of concentrations will activate the clone. The response of the clone to TNP-coupled allogeneic spleen cells is inhibited by anti-L3T4 and anti-Ia antibodies. In contrast, stimulation of the clone with syngeneic spleen cells coupled by using the same concentrations of TNBS is not inhibited with either anti-Ia or anti-L3T4 antibody. The inhibition pattern observed with anti-Ia and anti-L3T4 antibodies was also determined by the nature of the accessory population used to present soluble TNP-protein conjugates. Anti-I-Ad antibodies blocked the activation of clone Ly-1-T1 by TNP-protein plus splenic adherent cells, indicating the involvement of polymorphic I-A determinants in this response. Anti-L3T4 antibody had little or no effect on this response, suggesting that a significant L3T4-Ia interaction is not required. Finally, the response of the clone to activated B cells in the presence or absence of TNP-protein is exquisitely sensitive to inhibition by anti-L3T4 as well as anti-I-A antibodies. The data suggest that the requirement for an L3T4-I interaction depends on the combination of antigen and accessory cell type used to stimulate the clone.

Animals↗
PubMed1983

Sequential expression of new gene programs in inducer T-cell clones.

We have prepared a cDNA probe that detects genes that are rapidly and abundantly expressed after exposure of inducer T-lymphocyte clones to antigen or mitogen. All inducer cells tested express a characteristic set of new mRNA, and these mRNAs are not expressed after activation of other lymphocytes. This initial burst of mRNA synthesis is paralleled by synthesis and secretion of a family of polypeptides that mediate inducer cell activity, including T- and B-cell growth factors, interferon, and molecules that bind to antigen. Expression of this initial genetic program precedes mitosis and is replaced within 74 hr by a different genetic program, which may control further cell division. The action of these sequential sets of genetic programs defines two stages of the cell's differentiation and accounts for altered expression of the cell's immunological functions.

Animals↗