Biomedical subjects

J Hakimi

Publications and source records attributed to J Hakimi.

At least 19 recordsLinked to original sources

PubMed2001

Prophylactic and therapeutic effects of a humanized monoclonal antibody against the IL-2 receptor (DACLIZUMAB) on collagen-induced arthritis (CIA) in rhesus monkeys.

CIA in the rhesus monkey is an autoimmune-based polyarthritis with inflammation and erosion of synovial joints that shares various features with human rheumatoid arthritis (RA). The close phylogenetic relationship between man and rhesus monkey makes the model very suitable for preclinical safety and efficacy testing of new therapeutics with exclusive reactivity in primates. In this study we have investigated the prophylactic and therapeutic effects of a humanized monoclonal antibody (Daclizumab) against the alpha-chain of the IL-2 receptor (CD25). When Daclizumab treatment was started well after immunization but before the expected onset of CIA a significant reduction of joint-inflammation and joint-erosion was observed. A therapeutic treatment, initiated as soon as the first clinical signs of CIA were observed, proved also effective since joint-degradation was abrogated. The results of this study indicate that Daclizumab has clinical potential for the treatment of RA during periods of active inflammation and suppression of the destruction of the joint tissues.

Animals↗

PubMed2000

Is uterine papillary serous adenocarcinoma a manifestation of the hereditary breast-ovarian cancer syndrome?

BACKGROUND: Uterine papillary serous carcinoma (UPSC) shares common pathologic, genetic, and clinical features with other serous cancers of müllerian origin. The most common histologic type of ovarian tumor associated with BRCA mutations is papillary serous. Because of these histologic similarities, we postulated that, in some cases, UPSC may be a manifestation of a field defect in BRCA1 carriers, which also includes ovarian carcinoma, fallopian tube carcinoma, and primary peritoneal carcinoma. METHODS: Fifty-six living patients with UPSC were contacted through their treating physicians and agreed to a family history interview and to provide a blood specimen for BRCA testing. The protein truncation test was used to detect mutations in exons 10 and 11 of BRCA1 and in exon 11 of BRCA2. The presence of four common mutations was assessed by PCR-based specific assays. RESULTS: A high proportion of patients had a past history of breast cancer (11%) or a first-degree relative with breast cancer (29%). Four patients were from families with site-specific hereditary breast cancer. However, there was no clear example of the hereditary breast-ovarian cancer syndrome, and none of the 56 patients was found to carry a BRCA1 or BRCA2 mutation. CONCLUSIONS: BRCA mutations do not appear to predispose to UPSC and this type of cancer does not appear to be a manifestation of the classical hereditary breast-ovarian cancer syndrome. The observed association between UPSC and breast cancer may be due to the presence of mutations in other cancer predisposing genes.

Adult↗

PubMed2000

A rapid fluorescent multiplexed-PCR analysis (FMPA) for founder mutations in the BRCA1 and BRCA2 genes.

Mutations of the BRCA1 and BRCA2 genes account for approximately 80% of hereditary breast/ovarian cancer families, but the size of these two genes makes mutation analysis time-consuming and technically challenging. In some populations such as the Ashkenazi Jewish and the French-Canadian, a small number of recurrent founder mutations account for the majority of mutations in cancer families. We have therefore developed two rapid genetic screening tests, which allow us to detect three frequent frameshift mutations in the Ashkenazi Jewish population and five frameshift mutations in the French-Canadian population. These fluorescent non-radioactive methods permit the simultaneous detection of multiple mutations by generating multiplexed PCR-amplified gene fragments, and by discriminating these on the basis of their size in a denaturing polyacrylamide gel. Using these methods, we were able to correctly identify all mutants in a blinded analysis of 276 DNA samples, including 30 derived from paraffin-embedded tumor samples and 10 from buccal-cell brushes, with no false positive or false negative results. These techniques designed for the direct detection of recurrent mutations in the BRCA1 and BRCA2 genes, have the advantages of being efficient, sensitive, cost-effective, and are applicable to large scale screening for epidemiologic studies.

BRCA2 Protein↗

PubMed2000

Successful in vivo blockade of CD25 (high-affinity interleukin 2 receptor) on T cells by administration of humanized anti-Tac antibody to patients with psoriasis.

BACKGROUND: Daclizumab is a humanized antibody to the alpha-subunit (CD25) of the interleukin 2 (IL-2) receptor that blocks normal IL-2 binding to this receptor. Because IL-2 is a major stimulus for T-cell growth, blockade of the IL-2 receptor could be useful in treating T-cell-mediated (autoimmune) diseases. OBJECTIVE: Our purpose was to determine whether adequate concentrations of antibody were achieved in circulating blood and in psoriatic skin lesions to saturate CD25 receptors. We also intended to measure clinical effect and safety of this agent when used alone (without other immunosuppressive drugs) in psoriasis. METHODS: Nineteen patients with psoriasis in two centers received daclizumab at an initial dose of 2 mg/kg, then 1 mg/kg at weeks 2, 4, 8, and 12. To determine whether CD25 was blocked in vivo, flow cytometric studies measured (1) expression of CD25 on CD3(+) T cells derived from blood and (2) immuno-histochemistry measures of CD25(+) cells done on pretreatment and posttreatment biopsy specimens. Patients were followed up clinically with photographs and Psoriasis Area and Severity Index scores. RESULTS: This study showed a consistent blockade of CD25 in peripheral blood and tissue during the first 4 weeks of therapy while the dosing was every 2 weeks. Variable desaturation of receptors began after 4 weeks, which correlated with a reversal in disease improvement. Patients with a pretreatment Psoriasis Area and Severity Index score of less than 36 showed a mean reduction in severity by 30% at 8 weeks (P =.02). During the 16 weeks of treatment, a 44.8% decrease in expression of the IL-2 receptor alpha-subunit was found. The absolute T-cell counts were calculated and showed no significant changes during the course of the study. No significant adverse events were produced by daclizumab during this study. CONCLUSION: We therefore conclude that daclizumab is a well-tolerated agent that blocks CD25 expression in peripheral blood and skin. Furthermore, it may be useful in treating psoriasis in some patients.

Adult↗

PubMed2000

Significance of the CAG repeat polymorphism of the androgen receptor gene in prostate cancer progression.

PURPOSE: The CAG repeat polymorphism of the androgen receptor gene has been associated with an increased prostate cancer risk, and the repeat length correlated with cancer stage and grade at presentation. Men with an allele length of </= 18 CAG repeats have a 2-fold increase in risk for high-stage or high-grade prostate cancer, compared with patients with a longer CAG repeat. We examined the significance of the CAG repeat polymorphism of the androgen receptor gene for predicting prostate cancer progression among 318 patients treated by radical prostatectomy for clinically localized prostate cancer between 1987 and 1994. MATERIALS AND METHODS: Leukocyte DNA was collected and genotyping of the CAG repeat polymorphism was performed using a PCR-based direct sequencing method. Risk ratios were calculated for developing biochemical recurrence for patients associated with an allele length of </= 18 CAG repeats, compared with patients with an allele length of >18 CAG repeats, controlling for grade, stage and serum PSA level at diagnosis using Cox proportional hazard modeling. RESULTS: Overall, the CAG repeat allele was not predictive of recurrence; tumor grade, stage and PSA level at diagnosis were the only predictors of recurrence in a multivariate analysis. However, for patients at low risk for recurrence (Gleason score 2 to 6, stage pT2, and PSA </= 10 ng./ml.), the relative risk of recurrence associated with an allele of </= 18 CAG repeats was 8.07 (95% C.I., 2.02 to 32.2, p = 0.004), compared with patients with an allele length of >18 CAG repeats. In contrast, for patients at high risk of recurrence (Gleason score >/= 7, stage pT3/4, or PSA >10 ng./ml.), the relative risk associated with the </= 18 CAG repeat allele was 0.72 (95% C.I., 0.33 to 1.57, p = 0.41), compared with patients with the >18 CAG repeat allele. CONCLUSIONS: The length of the CAG repeat polymorphism of the androgen receptor gene may be important for prostate cancer recurrence among patients who are otherwise at low risk for recurrence after radical prostatectomy. These findings have potential implications for patient selection for adjuvant treatment, and for the development of novel treatments.

Alleles↗

PubMed1998

Collagen-induced arthritis in rhesus monkeys: evaluation of markers for inflammation and joint degradation.

The objective of this study was to analyse parameters in rhesus monkey collagen-induced arthritis (CIA) with which the inflammation and destruction of the joints can be described in quantitative terms. CIA was induced in genetically susceptible and resistant monkeys, which can be distinguished on the basis of the dominant resistance marker Mamu-A26. The disease course was monitored daily using a semiquantitative scoring system. Plasma samples were collected once or twice weekly and analysed for C-reactive protein (CRP). Urines were collected overnight once a week and analysed for excretion rates of the collagen cross-links hydroxylysylpyridinoline (HP) and lysylpyridinoline (LP). The results show that periods of active CIA are characterized by substantial weight loss and increased plasma CRP levels, followed shortly thereafter by increased excretion rates of the collagen cross-links HP and LP. Remission of the disease can be recognized by a decline in plasma CRP levels and especially an increase in body weight. The highest CRP levels were found in the most severely arthritic monkeys, indicating a possible relationship of the absolute plasma CRP levels to the severity of inflammation. During periods of active arthritis, increased excretion rates of collagen cross-links HP and LP in the urine were found. In particular, the major collagen cross-link in articular cartilage, HP, showed a strong increase (9- to 15-fold). The excretion rates of LP, which is considered as a bone-specific degradation marker, only increased 4- to 6-fold, thus indicating predominant destruction of cartilage and less of bone. In conclusion, the severity of CIA can be monitored in a quantitative manner using plasma CRP levels, urinary excretion rates of HP and LP, and body weights, superimposed on semiquantitative clinical scores. The parameters also facilitate a more objective assessment of the effect of anti-arthritic drugs in the model than with the clinical scores alone.

Amino Acids↗

PubMed1998

Treatment of uveitis with recombinant human interleukin-13.

AIM: To evaluate the anti-inflammatory cytokine interleukin-13 (IL-13) for the treatment of uveitis. METHODS: Uveitis was induced in monkeys by immunisation with human retinal S-antigen. Starting at the onset of disease, the animals were treated with IL-13 at 25 micrograms/kg, or vehicle control, injected subcutaneously once a day for 28 days. Intraocular inflammation was scored by indirect ophthalmoscopy for a period of 56 days. Circulating leucocyte levels were monitored. RESULTS: Uveitis started unilaterally in all but one animal. IL-13 inhibited inflammation both in the eyes in which the disease was present when the treatment was initiated (p = 0.0001), and in the contralateral initially negative eyes (p = 0.0001). After cessation of therapy, there was a progressive increase of inflammation in the IL-13 treated group. However, the beneficial effect of IL-13 extended into the 4 week follow up period. IL-13 produced an increase in circulating polymorphonuclear neutrophils and a decrease in lymphocytes. CONCLUSION: Administration of IL-13 appears to be a promising modality of treatment for severe uveitis.

Animals↗

PubMed1997

Bispecific humanized anti-IL-2 receptor alpha beta antibodies inhibitory for both IL-2- and IL-15-mediated proliferation.

Humanized anti-Tac (HAT) and Mik beta1 (HuMik beta 1) Abs directed at IL-2R alpha and IL-2R beta, respectively, inhibit IL-2 binding and biological activity and together act synergistically in vitro. The Abs have been used successfully in primate models of allograft rejection, graft-vs-host disease, and autoimmunity. We produced bifunctional humanized anti-IL-2R alpha beta Abs (BF-IgG) to combine the specificity of the two Abs into one entity by fusing HAT-producing NSO cells and HuMik beta 1-producing Sp2/0 cells. BF-IgG was purified using protein G-Sepharose affinity chromatography, followed by IL-2R alpha and IL-2R beta affinity chromatography and hydrophobic interaction chromatography. BF-IgG exhibited both anti-IL-2R alpha and anti-IL-2R beta specificities in binding assays. While the Ab binds the IL-2R with intermediate affinity (Kd = 2.82 nM), it does not inhibit IL-15 binding to its high affinity IL-15R. In Kit225/K6 (IL-2R alpha beta gamma+) cells, BF-IgG was 10-fold more potent than a HAT/HuMik beta 1 equimolar mixture in blocking IL-2-induced proliferation and, unexpectedly, was at least 65-fold more active than the mixture in blocking IL-15-induced proliferation. This dual inhibitory activity may be due to cross-linking of the IL-2R alpha and IL-2R beta, thus blocking IL-2 binding and possibly impeding the association of IL-2R beta with IL-15R. BF-IgG has potent immunosuppressant activities against both IL-2- and IL-15-mediated responses, and this antagonist could be more efficacious than HAT and/or HuMik beta 1 for the treatment of autoimmunity and the prevention of allograft rejection.

Antibodies, Bispecific↗

PubMed1997

A phase I trial of humanized anti-interleukin 2 receptor antibody in renal transplantation.

The efficacy of murine monoclonal anti-interleukin 2 alpha chain receptor (Tac) antibodies is limited by a short half-life and the development of antibodies to the heterologous protein. The safety, pharmacokinetics-dynamics, and immunosuppressive effect of a humanized anti-Tac antibody (HAT) was evaluated in 12 renal transplant recipients. Ten patients received living related transplants (three HLA-identical matches and seven one-haplotype or zero-haplotype matches) and two patients received cadaver organs. The patients were divided into four HAT treatment arms: 0.5 mg/kg/week (n=4), 1 mg/kg/week (n=2), 0.5 mg/kg every other week (n=3), and 1 mg/kg every other week (n=3). The first dose of HAT was given within 12 hr before transplantation, and four additional doses were given after transplantation. Patients were also placed on cyclosporine, steroids, and azathioprine. Only one patient, a recipient of a cadaver kidney in the lowest HAT treatment arm, had a reversible rejection episode. The 10 recipients of living related transplants were compared with 17 historical controls treated with an identical immunosuppressive regimen except for HAT. Whereas none of the HAT-treated living related donor recipients had a rejection episode, 6 of 17 (41%) of the historical controls had a rejection episode in the first year after transplantation. There were no first-dose reactions after HAT therapy or other subsequent side effects. None of the patients experienced opportunistic infections or malignancies. One patient developed low-titer anti-HAT antibodies, although the patient maintained high serum HAT concentrations throughout the study. Immune monitoring showed that there were no changes in the percentage or absolute counts of CD3 cells or T-cell subsets after HAT therapy. However, there was a significant decrease in the number of circulating lymphocytes that expressed free Tac. The overall harmonic mean half-life of HAT was 273 hr. The results of this study indicate that HAT given at 1 mg/kg every other week for a total of five doses may provide therapeutic HAT concentration levels and result in good saturation of Tac receptors for at least 12 weeks after transplantation. In summary, HAT is safe and is well tolerated by patients. Its long half-life and lack of immunization could make it a very useful immunosuppressive drug.

Adult↗

PubMed1997

Humanized antibodies against the alpha-chain of the IL-2 receptor and against the beta-chain shared by the IL-2 and IL-15 receptors in a monkey uveitis model of autoimmune diseases.

We studied the efficacy and tolerance of humanized Ab interfering with the signal of the IL-2 and IL-15 receptors in a primate model of experimental autoimmune uveoretinitis. The inhibitory effects of humanized anti-Tac (HAT), an anti-IL-2R alpha-chain Ab, and HuMik beta1, an Ab directed at the beta-chain shared by the receptors of IL-2 and IL-15, were tested in culture on the proliferative response of monkey Con A-blast lymphocytes stimulated with IL-2 or IL-15. Uveitis was induced in cynomolgus monkeys by immunization with human recombinant retinal S-antigen. Treatment was initiated at the first sign of disease and consisted of HAT and HuMik beta1, alone or in combination, or vehicle control given by i.v. injection twice a week for 4 wk. Disease was evaluated by ocular funduscopy. The results in culture showed a significant dose-dependent inhibition of the IL-2-driven proliferation of lymphocytes by HAT. HuMik beta1 alone was ineffective against IL-2 stimulation, but had a marked potentiating effect in combination with HAT, independent of IL-15 signaling. IL-15-driven proliferation was inhibited by HuMik beta1, but not by HAT alone or in combination. In monkeys, experimental autoimmune uveoretinitis evolution was significantly inhibited by HAT treatment. HuMik beta1 alone had no effect on the disease. However, when used in combination, the two Ab markedly reduced the severity of ocular inflammation. The Ab were well tolerated. Only three monkeys, treated with HAT alone, made an Ab response against the injected Ab.

Animals↗

PubMed1995

Distinction between gamma c detection and function in YT lymphoid cells and in the granulocyte-macrophage colony-stimulating factor-responsive human myeloid cell line, Tf-1.

Peripheral blood monocytes respond to interleukin-2 (lL-2) and express the gamma common (gamma c) subunit of the lL-2 receptor (lL-2R) complex. However, the role of lL-2 in myeloid development has recently become of interest for several reasons, including the effect gamma c mutations may or may not have on myeloid development in patients with XSCID. Many studies of lL-2 function in the myeloid cell lineage have been performed on a murine background. To study gamma c expression and function in human myeloid precursors, we introduced the human myelomonocytic cell line, Tf-1, with a retroviral vector containing the human lL-2R beta subunit to create functional human intermediate lL-2R consisting of beta gamma c dimers. We have characterized this transfected variant of Tf-1 (Tf-1 beta) with regard to its response to lL-2. Unlike the parental Tf-1 cell line that is deficient in both lL-2R alpha and lL-2R beta expression, the Tf-1 beta transfectant binds and responds to lL-2 through intermediate-affinity lL-2Rs. Scatchard analyses indicate the number of intermediate-affinity receptors on Tf-1 beta is similar to the number found on the well-characterized YT cell line. However, detection of gamma c on Tf-1 beta cells is dramatically less than on YT cells by Western blot analysis and is undetectable by flow cytometric studies and surface iodinations. The gamma c component on YT cells is readily detected by all three methods. We conclude from these studies that the intermediate-affinity lL-2Rs on the Tf-1 cell line behave differently than those on YT cells with respect to gamma c detection. Either the gamma c molecule itself is different, or the cellular environment in which it functions is altered. Elucidation of gamma c function on this cell line will allow for its use as a model in which other cytokines using gamma c (including lL-2, lL-4, and lL-15) can be studied on the same cellular background.

Animals↗

PubMed1995

IL-12 regulation of parasite antigen-driven IgE production in human helminth infections.

Recombinant IL-12 inhibits IgE synthesis by IL-4-stimulated lymphocytes from healthy persons and influences the development of Th subset selection involved in Ig isotype selection. Whether endogenous IL-12 production modulates IgE synthesis in patients with elevated serum IgE is unknown. To examine this question we studied the effects of neutralizing anti-IL-12 or recombinant IL-12 on parasite Ag-driven polyclonal IgE production and corresponding IFN-gamma and IL-4 synthesis by PBMC from helminth-infected individuals. The addition of neutralizing anti-IL-12 Ab significantly inhibited parasite Ag-driven IgE production in 11 of 12 individuals (p < 0.001). Recombinant IL-12 (1-10 U/ml) suppressed Ag-driven IgE production in a dose-dependent fashion up to 94% relative to untreated cultures. The effect of endogenous IL-12 on IgE production occurred, in part, by suppressing Ag-induced IL-4 and augmenting IFN-gamma production. IL-12 did not suppress IgE synthesis by purified B cells. An IFN-gamma-independent effect of IL-12 on Ag-driven IgE production was suggested by the ability of human rIL-12 to suppress IgE synthesis in the presence of neutralizing anti-IFN-gamma. This study demonstrates that IL-12 modulates helminth Ag-driven IgE production, in part, by regulating the relative quantities of IFN-gamma and IL-4 generated by Ag-specific lymphocytes.

Adult↗

PubMed1995

Human IL-12 p40 homodimer binds to the IL-12 receptor but does not mediate biologic activity.

IL-12, a heterodimeric cytokine, consists of two disulfide-linked subunits, p40 and p35. We investigated the role of p40 in ligand binding and signal transduction by expressing this subunit alone in COS cells. Culture media of the transfected COS cells exhibited specific dose-dependent binding to KIT225/K6 cells, a human T cell line that expresses IL-12R. Analysis of the culture media by SDS-PAGE and Western blotting demonstrated the presence of 40-kDa monomers and 80-kDa disulfide-linked homodimers. The two p40 species were purified and identified by N-terminal sequencing and proteolytic peptide mapping. Characterization of the p40 proteins for binding and bioactivity showed that both the p40 monomer and dimer inhibited 125I-labeled IL-12 binding to IL-12R, but the 80-kDa species, having a 50% inhibitory concentration (IC50) of 20 to 70 ng/ml, was at least 20-fold more effective than the monomer. Although neither the monomer nor the dimer stimulated human PHA-blast proliferation, the 80-kDa dimer inhibited IL-12-induced proliferation in a dose-dependent manner with an IC50 of 65 ng/ml. The results suggest that the IL-12 p40 subunit contains the essential epitopes for receptor binding. However, a proper conformation required for high affinity binding is achieved only when p40 is associated with a p35 subunit or another p40 subunit. When p40 is associated with a p35 subunit, the heterodimer acts as an agonist mediating biologic activity. However, when p40 associates with another p40, the homodimer behaves as an antagonist in vitro.

Animals↗

PubMed1995

Activated T cells induce interleukin-12 production by monocytes via CD40-CD40 ligand interaction.

Previous studies on the production of interleukin-12 (IL-12) have shown that it is released, together with other proinflammatory cytokines, shortly after exposure of phagocytic cells to a variety of pathogens. We here report that IL-12 is also released during the recall response to soluble antigen (Ag) devoid of intrinsic adjuvant activity. We show that activated T cells induce the production of IL-12 by monocytes via a mechanism involving the interaction of T cell-associated CD40 ligand with CD40 on monocytes. The data suggest that Ag presentation on monocytes favors the persistence of type 1 responses.

Antigen Presentation↗

PubMed1995

Preparation of a bispecific F(ab')2 targeted to the human IL-2 receptor.

The heterodimer-forming leucine zippers Fos and Jun can efficiently mediate the formation of bispecific F(ab')2 when they are fused separately to two different Fab' fragments. This recombinant method can be used in conjunction with the humanization process to yield humanized bispecific F(ab')2. The potential immunogenicity of the leucine zippers can be eliminated by their removal using pepsin digestion. This method has been scaled up to produce hundreds of milligrams of a bispecific F(ab')2 that targets two subunits of the human IL-2 receptor.

Amino Acid Sequence↗

PubMed1994

Evidence for an interleukin 4-inducible immunoglobulin E uptake and transport mechanism in the intestine.

Immunoglobulin (Ig) E is the principal Ig involved in immediate hypersensitivities and chronic allergic diseases such as asthma. Helminths are the most potent infectious agents known for their capacity to stimulate IgE production during the course of infection. In rats, the nematode Trichinella spiralis typically elicits a strong parasite-specific IgE response during infection, and this IgE antibody has been shown to be protective against the parasite in passive transfer experiments. The study reported here analyzed the fate of 125I-labeled myeloma IgE (1R162) in normal and T. spiralis-infected rats after intravenous injection. T. spiralis infection induced a capacity for specific binding to the gut wall of 125I-IgE rather than 125I-IgG1, as well as the transport of IgE, but not IgG1, into the gut lumen. Peak intestinal uptake and transport of 125I-IgE occurred during the first and second weeks after injection but was not elevated in the fourth week, that is, after intestinal adult worms had been expelled. Neither 125I-IgE uptake in the gut wall nor transport to the lumen could be ascribed to tissue damage or vascular leakage. Luminal transport occurred in the small intestine and not the liver, which only transports low molecular weight degraded 125I-IgE. Calculations based on the amount of intact IgE in the lumen suggest that, in a 24-h period, up to 20% of injected 125I-IgE can be transported to the gut lumen during the peak transport period, between 6 and 14 d after infection. The intestinal IgE binding and transport response can be adoptively transferred with T. spiralis immune CD4+ OX22- (CD45RC-) lymphocytes, which are protective, but not the nonprotective sister population CD4+ OX22+ (CD45RC+) of lymphocytes isolated simultaneously from thoracic duct lymph of infected rats. The intravenous infusion of recombinant rat interleukin 4 also elicited significant intestinal uptake of 125I-IgE. We also present evidence for the presence of CD23 on rat intraepithelial lymphocytes. These data provide evidence for a novel, inducible, intestine-specific IgE uptake and transport mechanism.

Animals↗

PubMed1994

Humanized antibody directed to the IL-2 receptor beta-chain prolongs primate cardiac allograft survival.

IL-2Rs are expressed by T cells activated in response to foreign histocompatibility Ags but not by normal cells. This difference in IL-2R expression is exploited by blockade of IL-2Rs to achieve immunosuppression. High affinity IL-2Rs involve three subunits, IL-2R alpha, IL-2R beta, and IL-2R gamma. Murine Mik beta 1, a mAb that blocks IL-2 binding to IL-2R beta, was developed as an immunosuppressive agent. There was modest prolongation of cynomolgus cardiac allograft survival in animals treated with murine Mik beta 1 (mean survival 11.8 +/- 1.6 days compared with 8.2 +/- 0.4 days in untreated animals; p = 0.06). However, murine Mik beta 1 is ineffective in recruiting primate effector cells and is neutralized by monkey Abs directed toward the infused Ab. To circumvent these limitations, a humanized form of Mik beta 1, which is a largely human IgG1k Ab, except that murine hypervariable regions are retained, was developed. In vivo plasma survival of humanized Mik beta 1 was threefold longer than simultaneously administered murine Mik beta 1 (terminal t1/2, 104 +/- 10 h vs 37 +/- 2 h). Furthermore, humanized Mik beta 1 manifests Ab-dependent cellular cytotoxicity, an activity that is absent with the parental murine Mik beta 1. Graft survival was significantly prolonged by humanized Mik beta 1 treatment with survivals of 22, 22, 24, 27, 44, and > 300 days (p vs control < 0.01; p vs murine Mik beta 1 < 0.01). Survival was not prolonged further (p > 0.3) by the addition of humanized anti-Tac, which blocks interaction of IL-2 with IL-2R alpha subunits. There was no toxicity attributable to the use of Mik beta 1 Abs. Thus, humanized Mik beta 1 prolonged cardiac allograft survival in primates without toxicity and may be effective as an adjunct to standard immunosuppressive therapy.

Animals↗

PubMed1994

Interleukin 12, interferon gamma, and tumor necrosis factor alpha are the key cytokines of the generalized Shwartzman reaction.

The Shwartzman reaction is elicited by two injections of lipopolysaccharide (LPS) in mice. The priming LPS injection is given in the footpad, whereas the lethal LPS challenge is given intravenously 24 h later. The injection of interferon gamma (IFN-gamma) or interleukin 12 (IL-12) instead of the LPS priming injection induced the lethal reaction in mice further challenged with LPS. Antibodies against IFN-gamma when given together with the priming agent, prevented the lethal reaction in mice primed with either LPS, IL-12, or IFN-gamma. Antibodies against IL-12, when given together with the priming agent, prevented the lethal reaction in mice primed with either LPS or IL-12 but not with IFN-gamma. These results strongly suggest that LPS induces the release of IL-12, that IL-12 induces the production of IFN-gamma, and that IFN-gamma is the cytokine that primes macrophages and other cell types. Upon LPS challenge, the lethal Shwartzman reaction is induced by a massive production of inflammatory cytokines that act on the target sites already sensitized by IFN-gamma. If mixtures of TNF and IL-1 or mixtures of TNF and IFN-gamma are used to challenge mice previously primed with IFN-gamma or IL-12, mortality is induced. In the same conditions, the individual cytokines or a mixture of IL-1 and IFN-gamma do not replace the LPS challenge. When the mice are primed with LPS, the combination of TNF, IL-1, and IFN-gamma induced only a partial mortality incidence suggesting that the involvement of other LPS-induced factors.

Animals↗