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Biomedical subjects

J Punnonen

Publications and source records attributed to J Punnonen.

At least 55 records · Page 3Linked to original sources
PubMed1993

Human Ig production and isotype switching in severe combined immunodeficient-human mice.

Severe combined immunodeficient (SCID) mice were transplanted with different human fetal organs (SCID-hu mice), including thymus, liver, spleen, and omentum, and the serum levels of human IgM, IgG, IgE, and IgA were measured. In all SCID-hu mice significant levels (up to 590 ng/ml) of IgM were detected, irrespective of the organs transplanted. In contrast, IgG was present (up to 530 ng/ml) only when the fetal thymus was transplanted together with the fetal liver, indicating that the presence of human T cell is a prerequisite for in vivo isotypes switching by human B cells in SCID-hu mice. Additional transplantation of fetal spleen did not significantly increase IgG levels. was observed 4 months after transplantation. At that time, analysis by IEF showed that human IgG present in SCID-hu serum was at least oligoclonal. Furthermore, all IgG subclasses were represented in the human IgG pool. Human B cells were undetectable in the peripheral blood, spleen, and bone marrow of these SCID-hu mice; in contrast, B cells expressing CD19 could be isolated from the SCID-hu thymus. Considerable proportions of the CD19+ B cells coexpressed CD5, CD7, CD10, CD40, and CD2. These B cells spontaneously produced IgM and IgG in vitro and could be induced to switch to IgE-producing cells when cocultured with cloned activated CD4+ T cells in the presence of IL-4. Collectively, these data demonstrate that functionally mature B cells able to produce IgM and IgG in vivo, and IgE in vitro, are present in the SCID-hu human thymus.

Animals↗
PubMed1993

The 26-kD transmembrane form of tumor necrosis factor alpha on activated CD4+ T cell clones provides a costimulatory signal for human B cell activation.

Interleukin 4 (IL-4) induces immunoglobulin (Ig)E and IgG4 synthesis in human B cells. In addition to IL-4, costimulatory signals provided by activated CD4+ T cells are required for productive IgG4 and IgE synthesis. Here we report that the 26-kD transmembrane form of tumor necrosis factor alpha (mTNF-alpha), which is rapidly expressed on CD4+ T cell clones after activation, contributes to the costimulatory signals resulting in IL-4-dependent Ig synthesis by B cells, including IgG4 and IgE production. mTNF-alpha expression was induced on T cell clones within 2 h after activation with concanavalin A. Peak expression was observed at 24 h, followed by a gradual decrease, but appreciable levels of mTNF-alpha were still detectable 72 h after activation. The presence of the 26-kD membrane form of TNF-alpha on activated T cell clones was confirmed by immunoprecipitation. Monoclonal antibodies (mAbs) recognizing mTNF-alpha, or the p55 TNF receptor, inhibited IgM, IgG, IgG4, and IgE synthesis induced by IL-4 and activated CD4+ T cell clones in cultures of highly purified surface IgD+ B cells. The anti-TNF-alpha mAbs also blocked Ig production in cultures in which the activated CD4+ T cell clones were replaced by their plasma membranes. Furthermore, pretreatment of the plasma membranes with anti-TNF-alpha mAbs strongly reduced their capacity to stimulate B cells to produce Ig in the presence of IL-4, indicating that the anti-TNF-alpha mAbs blocked the effects of mTNF-alpha. Anti-TNF-alpha mAbs did not affect IgM, IgG, IgG4, or IgE synthesis induced by anti-CD40 mAbs and IL-4 in the absence of CD4+ T cells, supporting the notion that the anti-TNF-alpha mAbs indeed interfered with the costimulatory, contact-mediated signal provided by T cells, or their membranes. Collectively these results indicate that mTNF-alpha, which is rapidly induced after activation of CD4+ T cells, participates in productive T-B cell interactions resulting in IL-4-induced Ig production. This is a novel property of the T cell membrane form of TNF-alpha.

Antibodies, Monoclonal↗
PubMed1993

Interleukin 13 induces interleukin 4-independent IgG4 and IgE synthesis and CD23 expression by human B cells.

Recently the cDNA encoding interleukin 13 (IL-13), a T-cell-derived cytokine, was cloned and expressed. The present study demonstrates that IL-13 induces IgG4 and IgE synthesis by human B cells. IL-13-induced IgG4 and IgE synthesis by unfractionated peripheral blood mononuclear cells and highly purified B cells cultured in the presence of activated CD4+ T cells or their membranes. IL-13-induced IgG4 and IgE synthesis is IL-4-independent, since it was not affected by neutralizing anti-IL-4 monoclonal antibody. Highly purified, surface IgD+ B cells could also be induced to produce IgG4 and IgE by IL-13, indicating that the production of these isotypes reflected IgG4 and IgE switching and not a selective outgrowth of committed B cells. IL-4 and IL-13 added together at optimal concentrations had no additive or synergistic effect, suggesting that common signaling pathways may be involved. This notion is supported by the observation that IL-13, like IL-4, induced CD23 expression on B cells and enhanced CD72, surface IgM, and class II major histocompatibility complex antigen expression. In addition, like IL-4, IL-13 induced germ-line IgE heavy-chain gene transcription in highly purified B cells. Collectively, our data indicate that IL-13 is another T-cell-derived cytokine that, in addition to IL-4, efficiently directs naive human B cells to switch to IgG4 and IgE production.

Antibodies, Monoclonal↗
PubMed1993

Interleukin 13, a T-cell-derived cytokine that regulates human monocyte and B-cell function.

We have isolated the human cDNA homologue of a mouse helper T-cell-specific cDNA sequence, called P600, from an activated human T-cell cDNA library. The human cDNA encodes a secreted, mainly unglycosylated, protein with a relative molecular mass of approximately 10,000. We show that the human and mouse proteins cause extensive morphological changes to human monocytes with an associated up-regulation of major histocompatibility complex class II antigens and the low-affinity receptor for immunoglobulin E (Fc epsilon RII or CD23). In addition, they stimulate proliferation of human B cells that have been activated by anti-IgM antibodies or by anti-CD40 monoclonal antibodies presented by a mouse Ltk- cell line transfected with CDw32. Furthermore, the human protein induced considerable levels of IgM and IgG, but no IgA production, in cultures in which highly purified human surface IgD+ or total B cells were cocultured with an activated CD4+ T-cell clone. Based on these findings, we propose that this immunoregulatory protein be designated interleukin 13.

Amino Acid Sequence↗
PubMed1993

The role of T/B cell interactions and cytokines in the regulation of human IgE synthesis.

Induction of immunoglobulin (Ig) isotype switching and isotype production by human B cells requires contact-mediated signals delivered by T helper cells in combination with cytokines. Effective T cell help requires T cell activation resulting in a rapid expression of T cell membrane proteins, which interact with ligands constitutively expressed on B cells. These interactions lead to B cell activation, proliferation and, in the presence of cytokines, to isotype switching and immunoglobulin synthesis. The nature of the T cell antigens involved in these T/B cell interactions, and their role in human B cell activation resulting in IgE synthesis in the presence of IL-4 and IL-13, will be discussed.

Animals↗
PubMed1993

Regulation of IgE synthesis by T cells and cytokines.

Human IgE synthesis is tightly regulated by cytokines. IgE production by normal B cells is specifically induced by IL-4, but requires additional, yet to be defined, signals that are provided by CD4+ T cells. Single surface IgM+ B cells can be induced to proliferate and switch to IgG4 and IgE producing cells, indicating that the induction of IgE synthesis by IL-4 and CD4+ T cells reflects direct isotype switching. Although IL-4 is the sole inducing cytokine of IgE synthesis known thus far, multiple cytokines modulate IL-4 induced IgE synthesis in vitro. IFN-alpha, IFN-gamma TGF-beta and IL-10 are inhibitory, whereas IL-5, IL-6 and TNF-alpha act synergistically with IL-4. Results obtained with animal models, as well as from clinical studies in the human have indicated that IL-4, IFN-alpha and IFN-gamma are operational in vitro. Cocultivation of B cells with allergen-specific CD4+ T cell clones producing high levels of IL-4 and IL-5, but normal to undetectable levels of IL-2 and IFN-gamma, following activation resulted in the synthesis of IgE, in the absence of exogenously added IL-4. These results indicate that aberrant ratio's of IL-4 and IFN-gamma production are sufficient for induction of IgE synthesis in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytokines↗
PubMed1993

Interferon (IFN)-alpha, IFN-gamma, interleukin (IL)-2, and arachidonic acid metabolites modulate IL-4-induced IgE synthesis similarly in healthy persons and in atopic dermatitis patients.

The role of cytokines and arachidonic acid metabolites in the regulation of IgE production in healthy persons and in atopic dermatitis patients with elevated IgE levels was studied. Interleukin-4 (IL-4) induced IgE production in peripheral blood mononuclear cells (PBMCs) of all donors, and no significant difference was found between the amounts of IgE produced by healthy persons and atopic dermatitis patients. Similarly, recombinant interferon (IFN)-alpha and IFN-gamma, as well as IL-2, inhibited IL-4-induced IgE production to a similar extent in both study groups. To evaluate the role of arachidonic acid (AA) metabolites in the regulation of IgE production, we added indomethacin, an inhibitor of the cyclooxygenase pathway, or nordihydroguaiaretic acid (NDGA), an inhibitor of the lipoxygenase pathway, to IL-4-treated cultures. Both indomethacin and NDGA strongly inhibited IL-4-induced IgE production. They also inhibited IL-4-induced IgG4 synthesis. No significant difference in the amount of inhibition was found between the two study groups. We were unable to restore the NDGA-induced inhibition of IgE-production by adding leukotrienes B4, C4, D4, or 5-HETE to the NDGA-treated cultures. PGE2 also failed to restore the indomethacin-mediated inhibitory effect. Consequently, NDGA- and indomethacin-mediated inhibitory effects do not appear to be mediated by any single factor studied. Collectively, our results show IFNs and IL-2 to be similar in effect in the modulation of IL-4-induced IgE synthesis in healthy and atopic persons.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Induction of isotype switching and Ig production by CD5+ and CD10+ human fetal B cells.

In the present study the capacity of early fetal B cells to produce Ig was investigated. It is shown that B cells from fetal liver, spleen, and bone marrow (BM) can be induced to produce IgM, IgG, IgG4, and IgE, but not IgA, in response to IL-4 in the presence of anti-CD40 mAb or cloned CD4+ T cells. Even splenic B cells from a human fetus of only 12 wk of gestation produced these Ig isotypes. IFN-alpha, IFN-gamma, and transforming growth factor-beta inhibited IL-4-induced IgE production in fetal B cells, as described for mature B cells. The majority of B cells in fetal spleen expressed CD5 and CD10 and greater than 99% of B cells in fetal BM were CD10+. Highly purified CD10+, CD19+ immature B cells and CD5+, CD19+ B cells could be induced to produce Ig, including IgG4 and IgE, in similar amounts as unseparated CD19+ B cells. Virtually all CD19+ cells still expressed CD10 after 12 days of culture. However, the IgE-producing cells at the end of the culture period were found in the CD19-,CD10- cell population, suggesting differentiation of CD19+,CD10+ B cells into CD19-,CD10- plasma cells. Pre-B cells are characterized by their lack of expression of surface IgM (sIgM). Only 30 to 40% of BM B cells expressed sIgM. However, in contrast to sIgM+,CD10+,CD19+ immature B cells, sorted sIgM-,CD10+,CD19+ pre-B cells failed to differentiate into Ig-secreting cells under the present culture conditions. Addition of IL-6 to these cultures was ineffective. Taken together, these results indicate that fetal CD5+ and CD10+ B cells are mature in their capacity to be induced to Ig isotype switching in vitro as soon as they express sIgM.

Antibody Formation↗
PubMed1992

Transforming growth factor-beta directs IgA switching in human B cells.

Transforming growth factor (TGF)-beta added to cultures of highly purified human splenic B cells induced high levels of IgA synthesis in the presence of PWM and activated cloned CD4+ T cells. TGF-beta had no effect on IgM or IgG production. The induction of IgA synthesis by TGF-beta reflected IgA switching, because a strong induction of IgA production was also observed, when sIgA- B cells were cocultured with cloned activated CD4+ T cells in the presence of pokeweed mitogen. Resting CD4+ T cell clones or activated CD8+, TCR-gamma delta + CD4-,CD8- T cell clones failed to provide the co-stimulatory signal that in addition to TGF-beta and pokeweed mitogen was required for induction of IgA switching and IgA synthesis. mAb against CD4 or class II MHC molecules inhibited TGF-beta induced IgA synthesis, indicating that CD4-class II MHC interactions are required for productive T-B cell contacts resulting in IgA production. In contrast, anti-LFA-1, anti-CD2, and anti-class I MHC mAb were ineffective. TGF-beta failed to induce IgA synthesis by sIgA+ B cells under these culture conditions. Interestingly, induction of IgA production by sIgA- B cells required neutralization of TGF-beta activity by addition of the anti-TGF-beta mAb 1D11.1G 24 h after onset of the cultures. IgA production was prevented when the anti-TGF-beta mAb was added at the start of the cultures, indicating the specificity of the reaction. IgA synthesis was completely suppressed when TGF-beta was present during the total culture period of 11 days. These findings indicate that TGF-beta can act as a specific switch factor for IgA, provided it is only present at early stages of the cultures.

Antibodies, Monoclonal↗
PubMed1992

Ontogeny of immunosuppressive activity, MHC antigens and leukocytes in the rat testis.

The levels of immunosuppressive activity and the presence of MHC antigens and leukocytes were studied in the immature and the sexually mature rat testis. The immunosuppressive activities were measured from high-molecular weight (greater than 5 kDa) fractions of testis extracts using the protectin bioassay. The presence of MHC antigens and leucocytes was studied using the indirect immunoperoxidase method. In the immature rats, clusters of class I MHC antigen positive cells and a few cells expressing class II MHC antigen were present in the testicular interstitium. In the sexually mature rats, all the cells were MHC I+, and MHC II+ cells were numerous in the testicular interstitium. The seminiferous epithelium was MHC-negative in both the immature and the sexually mature testis. W3/25+ leukocytes were present in the interstitium and the tubular wall in both the immature and the sexually mature rat testis, but not in the seminiferous epithelium at any age. At 20-30 days of age, the testicular extracts were neutral or slightly stimulated 3H-TdR incorporation into peripheral blood lymphocytes, but at 44-60 days of age they inhibited lymphocyte proliferation significantly. In gel filtration, a peak of immunosuppressive activity was observed at approximately 400 kDa (protectin A) in both 20- and 60-days-old rat testes. A smaller peak was present at approximately 200 kDa in both age groups. This study shows that the testicular immunoregulatory microenvironment is different in the immature and the sexually mature rats. This may be important in such age-dependent human diseases as mumps orchitis and the testicular relapses of acute lymphoblastic leukemia.

Age Factors↗
PubMed1992

Demonstration of tumor necrosis factor-alpha in preovulatory follicular fluid: its association with serum 17 beta-estradiol and progesterone.

In the present study we have measured the concentrations of interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) in preovulatory follicular fluid (FF) samples obtained from patients undergoing ovulation induction with human menopausal gonadotropin/human chorionic gonadotropin. In 13 of the 24 (54%) FF samples obtained from 20 patients, TNF-alpha was detected. In contrast, IL-1 beta was observed in none of the 16 samples assessed. In the samples with detectable levels of TNF-alpha, the mean concentration was 40.1 pg/ml (range 20-74 pg/ml). In addition, we found an association between the presence of TNF-alpha in the FF and the serum level of 17 beta-estradiol (E2) and progesterone (P). The E2 and P levels were significantly lower in patients with detectable levels of TNF-alpha in FF than in patients with no detectable TNF-alpha in FF. In summary, the present study shows the presence of TNF-alpha and the absence IL-1 beta in hyperstimulated human preovulatory FF. In addition, our results show an association between the presence of TNF-alpha in FF and low E2 and P levels in serum, suggesting a role for TNF-alpha in the regulation of human steroidogenesis.

Estradiol↗
PubMed1991

Production of interleukin-1 beta and tumour necrosis factor-alpha in patients with benign or malignant ovarian tumours.

To assess the role of interleukin-1 beta (IL-1 beta) and tumour necrosis factor alpha (TNF alpha) in the physiological host defence mechanisms against malignancies, the production of these cytokines in sera, ascitic and cyst fluids and in the tumour tissues of patients with benign or malignant ovarian tumours was studied. IL-1 beta was found neither in the sera nor in the ascitic fluids of these patients. It was also virtually absent from the cyst fluid samples. However, a mean value of 790 pg IL-1 beta/g tumour was found. Like IL-1 beta, TNF alpha was virtually absent in the serum samples. It was, however, detectable in the ascitic and cyst fluids and tumour tissues. The TNF alpha concentrations were highest in the tumour tissues, with a mean level of 328 pg/g tumour. When comparing the level of IL-1 beta and TNF alpha in patients with benign tumours to that seen in patients with malignant tumours, no differences in production were observed, regardless of the origin of the test samples. Our results indicate the production of IL-1 beta and TNF alpha in patients with ovarian tumours. More importantly, the finding that the production of these cytokines in patients with benign tumours is similar to that in patients with malignant tumours supports the conclusion that the production of these cytokines is more a nonspecific indicator of an inflammatory process than a specific response to a malignant process.

Adult↗
PubMed1991

Regulation of IgE synthesis by cytokines.

Considerable progress has been made in our understanding of the mechanisms underlying regulation of human IgE synthesis. Interleukin-4 induces IgE production specifically, but costimulatory signals provided by T cells are required. Other cytokines modulate interleukin-4-induced IgE synthesis. The roles of T cells and cytokines in regulating IgE switching are discussed.

Antibody Diversity↗
PubMed1990

Regulation of the testis.

The testicular cells are regulated by factors produced locally in the testis. These factors include peptide growth factors, pro-opiomelanocortin derivatives, neuropeptides and steroids. Several agents able to affect steroido- and spermatogenesis can also affect leukocytes and many of the testis-regulating factors are produced by immune cells, suggesting that testicular cells and leukocytes may interact. In the present article, the effects of various testicular cell and leukocyte produced factors on steroido- and spermatogenesis are reviewed. The possibility that leukocytes may produce substances able to affect the testicular functions suggests that inhibition of immune system activation in the testis may be important also for reasons other than protection of autoantigenic germ cells from an autoimmune attack.

Androgens↗
PubMed1989

The effect of storage of antigen-coated polystyrene microwells on the detection of antibodies against Borrelia burgdorferi by enzyme immunoassay (EIA).

Qualitative and quantitative changes in the antigenic mosaic of coated solid-phase matrices occurring during storage may have a pronounced effect on the comparability of results obtained by enzyme immunoassay (EIA). We have used, as a model antigen for studying the effects of storage, a sonic extract of Borrelia burgdorferi and a totally automatic EIA procedure. The IgM antibody concentrations of the sera originally determined to be high decreased by almost one half during 1 week's storage of the solid phase of 4 degrees C. In contrast, the IgM values of other sera, originally measured at medium or low, doubled upon storage. Thus, after storage the rank order of the sera was markedly affected compared to the values obtained with antigen freshly applied to the wells. In parallel determinations of IgG antibody levels the EIU relative unitage values of the test sera generally remained constant upon storage. The only exception was the serum with the highest original antibody concentration. Its relative antibody unitage more than tripled over the storage time. It is recommended that the coating of solid-phase matrices should be done immediately before each run in all EIAs where microbial extracts are used as antigens.

Antibodies, Bacterial↗
PubMed1989

Interferon-alpha and interferon-gamma as regulators of human adult and newborn B-cell function.

The role of interferon-alpha (IFN-alpha) and interferon-gamma (IFN-gamma) in the regulation of B-cell function was studied using highly purified tonsillar B-cells and unfractionated mononuclear cells from healthy adults and newborns. Recombinant IFN-gamma (rIFN-gamma) was found to enhance Staphylococcus aureus Cowan I (SAC)-induced proliferation of purified B-cells. Recombinant IFN-alpha (rIFN-alpha) neither enhanced nor inhibited the function of purified B-cells. However, when unfractionated mononuclear cells were studied, no enhancement in SAC- or pokeweed mitogen (PWM)-induced proliferation was found in response to these IFNs. In fact, the responses in these cultures were mainly inhibitory. The effects were dependent on the mitogen used for activation of the cells and on the source of the cells. The IFNs acted in a more inhibitory way in cultures stimulated with PWM than in those stimulated with SAC. In addition, they acted more suppressively in cord blood mononuclear cells (CBMCs) than in adult peripheral blood mononuclear cells. PWM was found to decrease CD4+/CD8+ T-cell ratio, and cells with suppressor function physiologically dominate among CBMCs. Thus, the effect of these interferons on B-cell function seems to depend on the magnitude of suppressor cell function among the cell population.

B-Lymphocytes↗