PubMed Health⌕ Search

Biomedical subjects

R H DeKruyff

Publications and source records attributed to R H DeKruyff.

At least 37 records · Page 2Linked to original sources
PubMed1998

Antigen-primed T cells from B cell-deficient JHD mice fail to provide B cell help.

B cells are effective in presenting Ag to primed T cells, but a specific role for B cells in priming naive T cells has not been clearly established. In this report we demonstrate that Ag administration to B cell-deficient JHD mice primes T cells for Ag-specific proliferative responses, but such primed T cells fail to provide help for isotype switching and IgG production in B cells. Although T cells primed in the absence of B cells could proliferate in response to Ag presented by B cells and could induce Ag-specific IgM production, such T cells failed to produce high levels of IL-4 as are normally induced in T cells by Ag-presenting B cells. These findings suggest that while B cells are not absolutely required for T cell priming, they provide signals to T cells that are not replicated by other APCs and that influence the subsequent ability of T cells to interact with B cells.

Animals↗
PubMed1998

Reduced prevalence of allergic disease in patients with multiple sclerosis is associated with enhanced IL-12 production.

BACKGROUND: We previously showed that the prevalence of allergic disease is decreased in patients with multiple sclerosis (MS); however, the mechanisms that explain this finding have not previously been defined. OBJECTIVES: We have demonstrated that protection of patients with MS from allergic disease may be caused by the production in monocytes from these patients of elevated quantities of IL-12 compared with that observed in monocytes from individuals with allergies. METHODS: Purified monocytes from peripheral blood of subjects with or without allergies and from individuals with MS were directly stimulated with Staphylococcus aureus Cowan strain I in the absence of T cells. IL-12 was quantitated by a sensitive reverse transcription, competitive PCR. RESULTS: IL-12 production was 5-fold greater in monocytes from patients with MS (n = 11) than that from individuals with allergies (n = 10) (for subjects with MS, 1.90+/-0.18 vs 1.24+/-0.19 log10 fmol/microL for individuals with allergies) (P = .02). Although the production of IL-12 in monocytes from patients with MS was slightly higher than that from subjects without allergies, this difference was not statistically significant. CONCLUSIONS: IL-12 production in individuals with MS is much greater than in individuals with allergies. Because IL-12 induces TH1 cytokine synthesis and reduces the production of TH2 cytokines, which amplify and prolong allergic inflammation, these studies suggest that enhanced IL-12 production may protect individuals with MS from the development of allergy but may predispose such individuals toward autoimmune inflammation in the central nervous system.

Adult↗
PubMed1997

Corticosteroids inhibit IL-12 production in human monocytes and enhance their capacity to induce IL-4 synthesis in CD4+ lymphocytes.

We examined the effects of corticosteroids on IL-12 production by human monocytes and on cytokine synthesis in T cells. To distinguish the effects of corticosteroids on the APC used to activate the T cell from direct effects of corticosteroids on the T cell, experiments were performed by exposing the APC and not the T cell to corticosteroids. We found that corticosteroids significantly inhibited the production in monocytes of IL-12, a cytokine that is extremely potent in enhancing IFN-gamma and inhibiting IL-4 synthesis in T cells. We demonstrated that reduced production of IL-12 in corticosteroid-treated monocytes resulted in a decreased capacity of the monocytes to induce IFN-gamma and an increased ability to induce IL-4 in T cells. These results suggest that although corticosteroids may be beneficial for the treatment of asthma or allergic disease due to direct inhibitory effects of corticosteroids on cytokine synthesis in T cells, chronic corticosteroid therapy may indirectly exacerbate the long-term course of allergic disease. This deleterious effect of corticosteroids would result from a limitation in IL-12 production in tissue monocytes and macrophages, which would enhance production of Th2 cytokines (which augment allergic disease), and would reduce production of Th1 cytokines (which attenuate allergic disease) in T cells that subsequently infiltrate the tissues.

Adult↗
PubMed1997

An ovalbumin-IL-12 fusion protein is more effective than ovalbumin plus free recombinant IL-12 in inducing a T helper cell type 1-dominated immune response and inhibiting antigen-specific IgE production.

Optimal treatment of allergic diseases requires that the cytokine profile of allergen-specific T cells be redirected, with the conversion of Th2 profiles into Th1 cytokine profiles. This conversion, however, is difficult, since Th2 effector cells have relatively fixed cytokine profiles. To more effectively redirect the cytokine profiles of T cells, we constructed a cytokine fusion protein that contained the Ag OVA, fused to IL-12. Immunization with the OVA-IL-12 fusion protein induced anti-OVA IgG2a Ab and large quantities of OVA-specific IFN-gamma production. The Ag specificity of this response was dependent upon covalent linkage of Ag and IL-12, since immunization of mice with OVA alone induced little or no IFN-gamma, while immunization with OVA and free rIL-12 enhanced T cell production of IFN-gamma, but the IFN-gamma production was not OVA specific. To examine the effects of OVA-IL-12 in reversing ongoing Th2-dominated immune responses, BALB/c mice previously primed with OVA in alum to induce a Th2-dominated response, were vaccinated with the OVA-IL-12 protein. In such mice, OVA-IL-12 was much more effective than OVA plus free rIL-12 in significantly increasing Ag-specific IFN-gamma production and significantly decreasing Ag-specific IL-4 production. Moreover, OVA-IL-12 increased serum anti-OVA IgG2a and decreased anti-OVA IgE. These studies indicate that OVA-IL-12 can convert immune responses characterized by high IL-4 and high IgE synthesis into Th1-dominated responses in an Ag-specific manner.

Animals↗
PubMed1997

Antigen-specific B cells preferentially induce CD4+ T cells to produce IL-4.

The role of Ag presentation by B cells in regulating the development of T cells with restricted cytokine profiles remains controversial. In this report, we compared Ag presentation by naive polyclonal B cells, naive Ag-specific B cells (from Ig receptor transgenic mice), or splenic adherent cells (SAC) and examined the capacity of these cells to influence cytokine production by CD4+ T cells. Freshly isolated naive B cells stimulated vigorous T cell proliferation and very strong T cell cytokine responses, but only when cultured with Ag recognized by the B cell Ig receptor (cognate Ag) and not when cultured with a noncognate Ag. Under these conditions, B cells activated by Ig receptor-mediated endocytosis of Ag induced both naive and Ag-primed CD4+ T cells to produce high levels of IL-4 (300-4000 pg/ml). In contrast, SAC induced the production of very low levels of IL-4 (<100 pg/ml) but much higher maximal levels of IFN-gamma than did Ag-specific B cells. The induction of IL-4 synthesis by Ag-specific B cells was significantly reduced by blocking CD40-CD40 ligand (CD40L) interactions or by the addition of small quantities of rIL-12. These results suggest that B cells activated by their cognate Ag preferentially induce IL-4 synthesis as a result of the interaction of CD40L on T cells with CD40, whereas SAC preferentially induce IFN-gamma synthesis by T cells as a result of their greater production of IL-12 and their limited capacity to trigger CD40L on T cells.

Animals↗
PubMed1997

Novel genetic regulation of T helper 1 (Th1)/Th2 cytokine production and encephalitogenicity in inbred mouse strains.

Development of T helper cell (Th)1 or Th2 cytokine responses is essential for effector and regulatory functions of T helper cells. We have compared cytokine profiles of myelin basic protein (MBP) Ac1-16 peptide-specific T helper cells from inbred mouse strains expressing identical k haplotype-derived MHC class II molecules B10.A and B10.BR, B10.BR T cell lines (TCL) produced Th1 cytokines (including high levels of TNF-alpha) and induced experimental autoimmune encephalomyelitis after adoptive transfer. In contrast, B10.A TCL produced Th2 cytokines (including low levels of TNF-alpha) and were poorly encephalitogenic. The contributions of the genetic origin of the T cells and the APC were explored. Serial restimulations of the B10.BR TCL with B10.A or (B10.A x B10.BR) F1 splenic antigen presenting cells (APC) during the establishment of TCL markedly reduced both Th1 cytokine production and encephalitogenicity. In addition, a single restimulation with B10. A splenic APC reduced IFN-gamma and TNF-alpha production by established Th1 MBP-specific Ak-restricted B10.BR TCL and by a Th1 KLH-specific, Ek-restricted B10.BR T cell clone. These studies suggest that B10.A and B10.BR APC differ in their ability to stimulate IFN-gamma and TNF-alpha production by mature Th1 cells and also influence their Th1/Th2 commitment in vivo. The nature of the downregulatory activity of B10.A APC on IFN-gamma and TNF-alpha production was explored. 2-hour supernatants from antigen-activated B10.A APC/TCL cultures or from B10.A APC activated by LPS had the same inhibitory effects on IFN-gamma and TNF-alpha production by B10.BR TCL. The downregulatory effects of B10.A APC are independent of TNF-alpha, IL-4, IL-10, IL-12p40, IFN-gamma, IL-13, TGF-beta, and PGE2. Thus, genetic difference(s) between B10.A and B10.BR APC appear(s) to control the production or activity of a novel soluble cytokine regulatory factor that influences Th1/Th2 commitment and controls production of IFN-gamma and TNF-alpha by mature Th1 cells.

Adoptive Transfer↗
PubMed1997

Ly1- (CD5-) B cells produce interleukin (IL)-10.

Interleukin (IL)-10 enhances humoral immunity by inhibiting macrophage activation and promoting the development of Th2 cytokine synthesis. In this study we investigated the ability of conventional Ly-1- (CD5-) B cells to produce IL-10 protein. Highly purified normal, naive splenic B cells from both BALB/c and C57BL/6 mice produced IL-10 in response to stimulation with the mitogen LPS. In addition, B cells from antigen primed mice also produced IL-10 upon antigen restimulation in vitro, as analyzed by ELISA and by bioassay. Removal of Ly-1+ B cells did not appreciably reduce IL-10 production, indicating that conventional Ly-1- B cells produced IL-10. These results indicate that normal Ly-1- B cells produce significant quantities of IL-10 during mitogen- or antigen-driven immune responses. The production of IL-10 by conventional B cells may enhance their capacity to promote humoral immune responses.

Animals↗
PubMed1997

Antigen-driven but not lipopolysaccharide-driven IL-12 production in macrophages requires triggering of CD40.

We demonstrated that two distinct pathways exist for the induction of IL-12 in APC. The first pathway for IL-12 production occurred during responses to T cell-dependent Ags such as OVA and required triggering of CD40 molecules on the APC. IL-12 production in this T cell-dependent system increased in direct proportion to Ag concentration and required TCR ligation but not CD28 costimulation. The second pathway occurred when bacterial products such as LPS or heat-killed Listeria monocytogenes were used to activate macrophages to produce IL-12 in the complete absence of T cells. In this second pathway, IL-12 production was completely independent of CD40 triggering. In both pathways, the presence of IFN-gamma was not required for induction of IL-12 synthesis when splenic adherent cells (SAC) from normal mice were used. However, addition of IFN-gamma to cultures of Th2 T cells and SAC increased IL-12 production two- to fivefold, and addition of rTNF-alpha with IFN-gamma further enhanced IL-12 production. The addition of TNF-alpha in the absence of IFN-gamma, however, had no effect on IL-12 production in the T cell-dependent pathway. Similarly, addition of TNF-alpha in the presence or the absence of IFN-gamma to cultures of LPS or heat-killed Listeria and SAC did not increase IL-12 production, but addition of IFN-gamma alone greatly enhanced IL-12 production, consistent with the idea that bacterial stimuli induce significant quantities of endogenous TNF-alpha production. These results indicate that the requirements for the induction of IL-12 production in T cell-dependent and T cell-independent responses differs mainly with regard to CD40 triggering. Furthermore, these results suggest that IL-12 production can be induced by bacterial products in patients with hyper-IgM syndrome who lack CD40 ligand expression and in those treated with soluble gp39 to interrupt CD40-CD40 ligand interactions.

Adjuvants, Immunologic↗
PubMed1997

DNA vaccination with cytokine fusion constructs biases the immune response to ovalbumin.

DNA vaccination may work through direct transfection of antigen presenting cells (APC), or by secretion of the encoded protein by muscle or skin cells for uptake by APC. If cytokines are attached to the antigen, they may influence APC or responding T cells to drive the response toward a Th1 or Th2 direction, and/or potentiate it in an antigen-specific manner. To test this concept, expression vectors were constructed containing the ovalbumin (OVA) gene either alone, or linked to cytokine genes including GM-CSF, IFN-gamma, IL-2, IL-4, IL-12, or a sequence encoding nine amino acids of IL-1 beta. These constructs expressed OVA-cytokine fusion proteins in vitro which retained cytokine bioactivity. C57BL/6 mice were injected intramuscularly with the DNA constructs. Little if any OVA-specific antibody was produced in response to any of the DNA constructs, except for OVA-IL-4. However, lymphocytes from BALB/c mice vaccinated with OVA-IL-12 and OVA-IL-1 beta constructs produced more IFN-gamma and less IL-4 during in vitro restimulation assays than did other groups. All constructs elicited OVA-specific cytotoxic responses which were maintained or even increased over 16 weeks. The OVA-IL-12 and OVA-IL-1 beta peptide constructs elicited the strongest cytotoxic responses at 2 weeks postinjection. Cytotoxic responses were seen in all animals, even those lacking OVA-specific Ab, and were not related to Ab level. These studies indicate that the humoral, cytokine, and cytotoxic responses to DNA vaccination can be effectively altered by certain cytokine fusion constructs.

Animals↗
PubMed1997

Th1 and Th2 CD4+ cells in the pathogenesis of allergic diseases.

Our understanding of the molecular and genetic etiologies of allergic disorders, which affect 20%-30% of the general population, has greatly improved over the past several years. Previously, research focused on examination of immediate hypersensitivity reactions, initiated by the cross-linking of IgE molecules on the surface of mast cells/basophils, resulting in the release of a host of mediators, which cause symptoms typified by acute anaphylaxis. Although there has been substantial progress in understanding the molecular biology of mast cell and basophil activation and of the regulation of IgE synthesis, recent studies have shifted attention to the cellular and molecular mechanisms that cause a broader allergic inflammatory response and underlie the more chronic and severe symptoms of allergy and asthma. In this report, we will review a substantial body of recent experimental work that has provided the basis for our new understanding of the allergic inflammatory response and the pathogenesis of allergic diseases. We will describe the recent progress in defining the immunological basis for allergic disease, and how subsets of helper CD4+ T cells secreting a specific array of cytokines (Th2 cytokines) regulate/cause allergic inflammation. We will review the cell biology of Th2 cells, the role of Th2 cells in allergic disease, and biological, genetic, and therapeutic mechanisms that influence the differentiation of CD4+ T cells and enhance or suppress cytokine synthesis in Th2 cells. These mechanisms control the expression of allergic diseases, which occur in some but not all individuals following environmental exposure to allergens.

Animals↗
PubMed1996

Reconstitution of germinal center formation in nude mice with Th1 and Th2 clones.

We investigated the ability of hemocyanin (KLH)-specific cloned CD4+ T cells expressing defined cytokine profiles to support germinal center (GC) formation in syngeneic athymic recipients in response to hapten-KLH challenge. Th1 clones producing IL-2 and IFN-gamma did not by themselves increase GC production above background, while Th2 cells producing IL-4 and IL-5 did. However, the combination of Th1 and Th2 cytokines was more effective than Th2 cytokines alone, suggesting a synergistic effect in this aspect of their help for B cells. In contrast to GC formation, antibody production could be induced with Th1 or Th2 clones given separately (Th1 clones inducing IgG2a, and Th2 clones inducing IgG1 and IgE). These results indicate that the T cell requirements for GC production are different from those for isotype switching and Ig secretion. It is postulated that the synergy between Th1 and Th2 cells in the induction of GC formation reflects the synergy between Th1 and Th2 cytokines, such as IFN-gamma and IL-5, in promotion of GC cell proliferation.

Adoptive Transfer↗
PubMed1996

Cross-linking of the CD40 ligand on human CD4+ T lymphocytes generates a costimulatory signal that up-regulates IL-4 synthesis.

Although there is good evidence that the induction of IL-4 synthesis in CD4+ T lymphocytes is favored by Ag presentation by B cells and not macrophages, the precise molecular signals provided by B cells to T cells that enhance IL-4 synthesis are not clear. To examine this issue, we established an APC-independent system to activate highly purified T cells and induce cytokine synthesis, using immobilized mAbs against several T cell surface molecules, including CD3, CD28, and the CD40 ligand (CD40L). The counter-receptors for all three of these molecules are expressed on B cells, and include CD40, which is expressed primarily on B cells, but also on dendritic cells and thymic epithelium. We found that IL-4 synthesis was greatly enhanced by triggering of CD40L on the T cell surface in conjunction with ligation of CD3/TCR and CD28, whereas ligation of CD3/TCR and CD28 in the absence of CD40L triggering resulted in little or no IL-4 synthesis. CD40L costimulation greatly enhanced IL-4 synthesis both in T cells from normal nonallergic adult subjects as well as in naive T cells from cord blood. Furthermore, we demonstrated that IL-4 synthesis was optimally enhanced when the strength of the CD3/TCR signal was limiting, while IL-4 synthesis was inhibited when CD3/TCR stimulation was maximal. These studies confirm that IL-4 synthesis can be induced in normal T lymphocytes in the absence of exogenous IL-4, and demonstrate that CD40L costimulation is of fundamental importance in regulation of IL-4 production. In addition, these findings provide a mechanism by which B cells preferentially enhance IL-4 synthesis in T cells at low Ag concentrations.

Adult↗
PubMed1996

Ligation of TAPA-1 (CD81) or major histocompatibility complex class II in co-cultures of human B and T lymphocytes enhances interleukin-4 synthesis by antigen-specific CD4+ T cells.

We have previously shown that CD4+ T cells from allergic individuals are predisposed to producing interleukin (IL)-4 in response to allergens. IL-4 production could be modulated by antigen concentration as well as by the type of antigen-presenting cells (APC), with B lymphocytes inducing greater quantities of IL-4 than monocytes. Using this system we examined IL-4 synthesis after culture of CD4+ T cells with B cells, monocytes, or both, as APC in the presence of allergen and a monoclonal antibody against CD81 (TAPA-1), a member of the TM4 superfamily of proteins that regulates activation, proliferation and trafficking of B cells. Addition of anti-CD81 mAb during culture enhanced IL-4 synthesis by 2- to 70-fold over that using an isotype-matched control mAb. Furthermore, anti-CD81 mAb enhanced IL-4 synthesis in CD4+ T cells only when CD4+ T cells were cultured with B cells but not monocytes as APC, indicating that anti-CD81 mAb affected IL-4 synthesis in T cells via interactions with B cells. However, pretreatment of either population separately with anti-CD81 mAb prior to culture had no effect on subsequent IL-4 synthesis, suggesting a requirement for temporal or cooperative interactions between T and B lymphocytes. In addition, anti-CD81 mAb enhanced IL-4 production but reduced CD4+ T cell antigen-specific proliferation, demonstrating that IL-4 production and proliferation by CD4+ T cells were inversely related. Finally, mAb to major histocompatibility complex class II but not to anti-CD19 also enhanced IL-4 synthesis when B lymphocytes were used as APC. In all instances, enhancement of CD4+ IL-4 synthesis correlated with the presence of large cell aggregates in T-B lymphocyte cocultures. These results indicate that the capacity of B cells to induce IL-4 can be significantly enhanced by ligation of particular molecules on their surface and should aid in the design of treatments for diseases in which modulation of the cytokine profile would be beneficial.

Antibodies, Monoclonal↗
PubMed1996

Differential production of IL-12 in BALB/c and DBA/2 mice controls IL-4 versus IFN-gamma synthesis in primed CD4 lymphocytes.

The profile of cytokines produced by CD4 T cells is profoundly influenced by the presence of IL-12. Here we demonstrate that during re-stimulation of antigen-specific immune responses in vitro, antigen-primed lymph node cells from DBA/2 mice produced 3- to 30-fold more IL-12 than did cells from BALB/c mice, which are identical at the major histocompatibility locus. The strain differences in IL-12 production were observed only in antigen-driven responses (and not in responses induced by bacterial products), and were dependent upon an interaction between CD4 T cells and lymph node adherent cells. In addition, differences in the quantity of IL-12 produced by DBA/2 and BALB/c antigen-presenting cells (APC) was not dependent on differential production of IFN-gamma by T cells, since APC from DBA/2 mice still produced much greater quantities of IL-12 than did BALB/c APC when each was cultured with the same H-2d-restricted Th2 clones, in the complete absence of IFN-gamma, or when each was cultured with primed (BALB/c x DBA/2)F1 T cells. The level of IL-12 produced in the cultures critically affected cytokine production in CD4 T cells, since neutralization of endogenous IL-12 in DBA/2 cultures, which are predisposed towards developing Th1 responses, reduced IFN-gamma production and enhanced IL-4 synthesis to levels normally seen in BALB/c cultures, which are predisposed toward developing Th2 responses. We propose therefore that differential production of antigen-driven IL-12 is a mechanism by which the genetic background in DBA/2 and BALB/c mice can affect the pattern of cytokine synthesis by T cells during the development of adaptive immune responses.

Adjuvants, Immunologic↗
PubMed1995

IL-12 inhibits the production of IL-4 and IL-10 in allergen-specific human CD4+ T lymphocytes.

IL-12 influences cytokine synthesis in unprimed CD4+ T cells by enhancing IFN-gamma synthesis and enhancing the development of Th1 cells, but its effects upon Ag-primed T cells, which are thought to have relatively fixed cytokine profiles, is less clear. We investigated the capacity of IL-12 to modify cytokine synthesis in allergen-specific human CD4+ T lymphocytes from allergic donors after in vitro stimulation. CD4+ T cells were obtained from the peripheral blood of subjects with allergic rhinitis, depleted of activated T cells, and cultured with APCs and allergen. IL-12 dramatically inhibited the development of IL-4 and IL-10 synthesis, while it enhanced T cell secretion of IFN-gamma and IL-2, and enhanced Ag-specific T cell proliferation. The inhibitory effect of IL-12 on IL-4 synthesis was not dependent on the presence of IFN-gamma, was greatest when IL-12 was added at the initiation of culture, and was minimal when added late, indicating that resting memory CD4+ T cells were more sensitive than activated CD4+ T cells to the effects of IL-12. The effect of IL-12 on IL-4 and IL-10 synthesis was not dependent on the APC type, because IL-12 decreased IL-4 synthesis when either B cells or monocytes served as APCs. These results indicate that IL-12 may be therapeutically beneficial in the treatment of allergic diseases in which allergen-specific T cells characteristically produce enhanced quantities of IL-4 and IL-10.

Antigen-Presenting Cells↗
PubMed1995

IL-12 inhibits IL-4 synthesis in keyhole limpet hemocyanin-primed CD4+ T cells through an effect on antigen-presenting cells.

Although IL-12 is known to enhance IFN-gamma synthesis in unprimed CD4+ T cells, the effect of IL-12 on IL-4 synthesis in primed CD4+ T cells, which are thought to have relatively fixed cytokine profiles, has not been clearly examined. We examined the effects of IL-12 on cytokine production by CD4+ keyhole limpet hemocyanin (KLH)-primed memory lymph node T cells and by already established KLH-specific CD4+ T cell clones. First, we found that the presence of IL-12 greatly reduced the development of IL-4 synthesis in resting but not activated memory CD4+ T cells. Although IL-12 did not inhibit the production of IL-4 in cloned Th2 effector cells, it greatly inhibited the development of IL-4 synthesis in primed CD4+ T cells taken from the lymph nodes of mice previously immunized with KLH. Secondly, we found that IL-12 inhibited IL-4 synthesis either when directly added to cultures of T cells or when APC were preincubated in IL-12. Inasmuch as the enhancing effect of IL-12 on IFN-gamma synthesis occurred optimally only when the T cells were cultured directly in IL-12, these studies indicate that IL-12 affects IL-4 synthesis via a mechanism that involves APC, a process that differs from that by which it affects IFN-gamma synthesis. These studies also indicate that the administration of IL-12 would be clinically useful in treating patients, for example those with allergic disease or lepromatous leprosy, in whom memory T cells inappropriately overproduce IL-4.

Animals↗