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PubMed2003

A road less travelled: large animal models in immunological research.

The main advances in immunology have been forged or underpinned by animal experiments. However, animal research now focuses excessively on one laboratory species, and there is too much redundant repetition and too few transfers from basic discovery to successful clinical application. These features can be improved markedly by placing more emphasis on biological relevance when evaluating animal models and by taking greater advantage of the unique experimental opportunities that are offered by large animals.

Allergy and Immunology↗
PubMed1991

Validation of a non-invasive technique to assess development of airway hyperreactivity in an animal model of immunologic pulmonary hypersensitivity.

Airway hyperreactivity (AHR) is considered to be a prominent and consistent feature of the asthmatic. Accordingly, in developing animal models of asthma, it is important to have methodologies available for repeated assessment of airway reactivity (AR). We have described a methodology to assess AR in conscious minimally restrained guinea pigs, AR being quantified as the airborne concentration of histamine (mg m-3) necessary to produce a mild airway constriction. The present study sought to validate that methodology by assessing its ability to detect changes in AR associated with immediate-onset pulmonary hypersensitivity responses. Guinea pigs were sensitized by intraperitoneal injection of ovalbumin (OA) and challenged with OA aerosol 3 weeks later. All animals developed severe immediate-onset airway constrictive responses. AR was assessed 1 h later, upon return to normal breathing patterns. Hyperreactivity was apparent from response to 0.50 mg m-3 histamine when compared with 2.10 mg m-3 histamine needed for baseline response. In control, sham sensitized animals AR remained at 2.12 mg m-3 after OA inhalation challenge. The results demonstrate the ability of this methodology to detect airway hyperreactivity to histamine resulting from a pulmonary hypersensitivity response. By requiring neither surgery nor any invasive procedure, the technique is appropriate for serial measurements of AR as is needed in development of an animal model for asthma, a chronic airway disease.

Animals↗
PubMed1976

The 13C-N.M.R. spectra of disaccharides of D-glucose, D-galactose, and L-rhamnose as models for immunological polysaccharides.

Complete assignments of the 13C-n.m.r. spectra of disaccharides having beta-glycosidic linkages are presented and discussed. The disaccharides of D-glucose, D-galactose, L-rhamnose, 2-acetamido-2-deoxy-D-glucose, and 2-acetamido-2-deoxy-D-galactose are model compounds for 13C-n.m.r. studies of immunological polysaccharides. Changing the nature of the reducing glucopyranose rings (D-glucose to L-rhamnose) has no important influence on the chemical shifts of the carbons of the non-reducing glucopyranose ring (D-glucose). The converse is also true: the chemical shifts of the carbons of the reducing glucopyranose ring (L-rhamnose) are not noticeably affected by a change of the non-reducing unit (D-glucose to D-galactose or 2-acetamido-2-deoxy-D-glucose).

Disaccharides↗
PubMed1984

T helper cell inclusion into the mathematical model of immunological tolerance.

The experimentally observed recovery from tolerance to HSA in chickens is much slower than the values calculated by means of the simple mathematical model of B cell tolerance. The model assumes that tolerance is due to elimination or irreversible inactivation of immunocompetent cells reactive to the tolerated antigen, and that the recovery from tolerance is caused by the differentiation of new immunocompetent cells. Even when two collaborating B cell populations reactive to HSA were considered, the calculated recovery from tolerance was much slower than the observed one. Therefore, T helper cell tolerance was suspected and included into the mathematical model. The experimental data agreed best with the calculated values of the recovery from tolerance to HSA obtained with a T cell lifespan of 200 days. On the other hand, when two T helper cell populations cooperated with B cells in anti-HSA antibody production, the curve best fitting the experimental data corresponded to the T cell lifespan of 60 days.

Animals↗
PubMed2006

[Clozapine-induced agranulocytosis: genetic risk factors and an immunologic explanatory model].

BACKGROUND: Clozapine, an atypical antipsychotic used in the treatment of refractory schizophrenia, causes agranulocytosis in 0.8% of patients. The risk factors for clozapine-induced agranulocytosis (CIA) and the underlying mechanisms are unclear. AIM: To ascertain the genetic and immunological risk factors for CIA, and on the basis of these findings to construct an explanatory model for CIA. METHOD: We reviewed the literature via Medline (from 1966 to May 2004) and EMBASE (from 1980 to May 2004) using the search terms 'clozapine' and 'agranulocytosis'. RESULTS: We found 8 case-control studies that fulfilled our selection criteria. In schizophrenia patients, CIA appeared to be significantly associated with certain haplotypes of HLA (human leukocyte antigens) genes, with the 4b,3d microsatellite alleles of TNF (tumor necrosis factor), with variant genes of HSP 70 (heat-shock protein), and with NQO2 (dihydronicotinamide riboside quinone oxidoreductase) gene polymorphism. Most of these genetic findings are interrelated. Gene abnormalities of this kind probably play an important aetiological role in CIA and may provide a basis for the construction of an immuno-toxic explanatory model for CIA. CONCLUSION: It seems likely that CIA can be explained on the basis of genetic and immunotoxic factors. The model should help us to understand how agranulocytosis can be caused by various antipsychotics and how it can be treated. However, it is not yet possible to identify patients who are particularly at risk for CIA.

Agranulocytosis↗
PubMed1983

Mathematical modeling in immunology.

The first step in the sequence of events leading to antibody synthesis and secretion is antigen encounter by B cell receptors. The reaction leads to major membrane perturbations, including the capping and endocytosis of receptors. These events might play an important role in various aspects of the B cell response, but they are not well understood, and in any event it seems unlikely that a satisfactory explanation of response regulation to most antigens can be advanced in terms of these phenomena alone, without explicit consideration of other cell populations. Suppressor and helper T cell populations qualitatively and quantitatively regulate the response to almost all antigens. Knowledge of the antigen dose dependence of the response of these populations will undoubtedly be important for a complete understanding of major immune response phenomenology such as suppression and affinity regulation. T cell dose response patterns are currently unavailable, nor is much known of the molecular mechanisms mediating interactions among antigen responsive T cells. In order to explain why this information is important, and to connect disparate data on immunoregulation in a simple way, I introduced dose response patterns based on analogy with basophils, assumed cell interactions mediated by autoantiidiotypic antibodies, and briefly pursued the consequences. In the final section, the genetic experiments that are providing information on the molecular constraints on cell interactions were mentioned, and some of the outstanding theoretical questions were briefly discussed.

Animals↗
PubMed1996

Immune response to polyvalent melanoma cell vaccine in AJCC stage III melanoma: an immunologic survival model.

BACKGROUND: Our polyvalent, allogeneic melanoma cell vaccine (MCV) induces immunoglobulin M (IgM) and immunoglobulin G (IgG) class antibodies to a 90-kDa glycoprotein melanoma-associated antigen (MAA). Additionally, MCV induces delayed-type hypersensitivity (DTH) responses that we previously correlated with survival. We hypothesized that early DTH responses to MCV and early humoral responses to the 90-kDa MAA expressed on MCV cells may be predictive of overall survival. We tested this hypothesis by monitoring immunologic profiles in 59 patients with melanoma who were receiving MCV after surgical resection of regional lymph node or soft-tissue metastases. METHODS: Blood was drawn before vaccine administration, biweekly for 6 weeks, and then monthly. DTH to MCV was recorded at 0, 2, 4, and 8 weeks of MCV therapy. Mean antibody titers during the first 6-week interval were calculated. Changes in DTH were calculated as the difference between peak and prevaccine values (delta DTH). RESULTS: At a median follow-up of 75.6 months (range 5-138), univariate analysis assigned prognostic significance to gender (p = 0.046), lymph node involvement (p = 0.024), delta DTH (p = 0.044), mean anti-90-kDa MAA IgG (p = 0.0009), and mean anti-90-kDa MAA IgM (p = 0.0014). In multifactorial analysis, only the three immunologic variables significantly impacted survival (p = 0.046, 0.0005, and 0.0053, respectively). A mathematical model based on delta DTH and mean anti-90-kDa MAA IgG and IgM titers closely approximated the observed individual and overall survival rates. CONCLUSIONS: The correlation between overall survival and initial humoral/cellular immune responses to MCV immunotherapy may be useful in selecting patients most likely to benefit from prolonged adjuvant immunotherapy.

Adolescent↗
PubMed2000

Effects of the phosphodiesterase 4 inhibitor RPR 73401 in a model of immunological inflammation.

The study was performed to investigate effects of the phosphodiesterase 4 inhibitor RPR 73401 [N-(3, 5-dichloropyrid-4-yl)-3-cyclopentyl-oxy-4-methoxybenzamid] on an allergic skin reaction. To simulate an immunological inflammation, BALB/c mice were sensitized to dinitrochlorobenzene or toluenediisocyanate. At first, the abdominal skin was shaved and 50 microliter Freund's adjuvant were injected intracutaneously once. Then, the horny layer was removed by adhesive tape stripping and 100 microliter 0.5% dinitrochlorobenzene or 5% toluenediisocyanate were administered on the epidermis for 4 days. After repeated local treatment of the ear skin with 20 microliter 3% RPR 73401 or intraperitoneal administration of 1 and 5 mg/kg RPR 73401, 20 microliter 1% dinitrochlorobenzene or 0.5% toluenediisocyanate were given topically as a challenge. The vehicle controls showed a high increase in ear thickness over 48 h after challenge, whereas RPR 73401 administered on either route reduced this increase significantly. Nevertheless after topical administration, RPR 73401 had a longer lasting effect. These and other results may point to an indication for RPR 73401 in immunological dermatitis.

Administration, Topical↗
PubMed2005

Markov modelling of immunological and virological states in HIV-1 infected patients.

The purpose of this study was to evaluate the evolution of HIV infected patients and to bring out some significant factors associated with this pathology. The main criteria revealing the State of illness is viral load measurement (VL). However the CD4 lymphocytes also represent an important marker as these reflect the State of the immune reservoir. Many studies have been carried out in this field and different models have been proposed with a view to a better understanding of this disease. Multi State Markov models defined in terms of CD4 counts, or in terms of viral load, have proved to be very useful tools for modelling HIV disease progression. The model we have developed in this study is based on both the CD4 lymphocytes counts and VL. Markov models are characterized by transition intensities. In this paper we explored several structures in succession. First, we used a homogeneous continuous time Markov process with four states defined by crossed values of CD4 and VL in a given patient at a given time. Then, the effect of certain covariates on the infection process was introduced into the model via the transition intensity functions, as with a Cox regression model. Since the hypothesis of homogeneity may be unrealistic in certain cases, we also considered piecewise homogeneous Markov models. Finally, the effects of covariates and time were combined in a piecewise homogeneous model with a covariate. We applied these methods to data from 1313 HIV-infected patients included in the NADIS cohort.

Age Factors↗