METHOD FOR DETECTING ALLERGY

Abstract: The present invention comprises a simple way of identifying the tendency towards allergy or allergy already broken out, and showing the probability of allergy in a patient, by measuring the receptor expression of the phagocytic cells of peripheral blood. With a logistic regression model a combination of variables were found which best describe the probability of allergy. Thus the invention relates to a method for detecting allergy and a test kit for accomplishing the method. The invention also relates to a sensitive and specific logistic model for determining the probability of allergy.

Description: Method for detecting allergy Field of the invention The present invention comprises a simple way of identi¬ fying the tendency towards allergy or allergy already broken out, by measuring receptor expression of the pha¬ gocytic cells of peripheral blood. A combination of va¬ riables is also presented which best describe the proba- bility of allergy. Thus the invention relates to a method for detecting allergy and a test kit for accomplishing the method, as well as to a method for determining the probability of allergy by using a logistic regression model. Background of the invention Allergic diseases are nowadays a very large problem of public health, and morbidity to allergy seems to be in- creasing. Food allergies are usually the first manifesta¬ tion of allergy, and they are commonest in children under 3 years. After recedence of food allergy another allergic disease can later be developed in the patient. The defence mechanisms of foreign substances are specific as e.g. antibody response, or non-specific as e.g. the defence reactions mediated through phagocytic inflammato¬ ry cells or complement and other proteins. The mechanisms have mutual regulation. Usually the primary phase comp- rises phagocytosis and the secondary phase the specific immune response. This is why measuring the parameters related to phagocytosis gives firsthand information of a possible sensitization which leads into allergy. The as early as possible detection of the tendency to¬ wards allergy enables effective treatment of food allergy and preventive measures against other allergies. In the diagnostics of allergy skin prick tests and deter¬ mination of allergen specific IgE antibodies are general¬ ly used. However, these methods are useful only if the allergy is IgE-mediated, i.e. immediate or type I reacti- on. On the other hand the tests measuring the type I re¬ action are known to be unreliable in children under two years by whom allergy and especially food allergy is com¬ mon and the IgE response develops slowly. Recent placebo- controlled predisposition tests carried out using double- blind techniques show that patients with food allergy can be divided into groups on the basis of the way of the reaction (skin, intestines, respiratory tract) and the time of the reaction (immediate and delayed reactions and intermediary forms thereof). Especially in the diagnosis of food allergy with intes¬ tinal symptoms, and delayed food allergy (type III or type IV) the usefulness of the above mentioned methods is restricted, and distinguishing between allergic and other intestinal symptoms is especially difficult. The allergic inflammatory reaction caused by nutritives always causes changes in the intestinal mucous membrane, although the disease would show itself in e.g. skin. The early detect¬ ion of the inflammatory changes has also importance for the prognosis of the patient. Tendency towards allergy or allergy already broken out can be detected and monitored by measuring the expression of the receptors related to the phagocytosis of monocytes and neutrophils. The phagocytic cells have their own part in the origin of symptoms accompanied with allergy and especially food allergy. Phagocytic cells are able to release into the ambient tissue lytic enzymes and reacti¬ ve forms of oxygen which are essential parts of the de- fence mechanism of the cell. Phagocytic cells receive their secreting signals through the receptors accompanied with phagocytosis. These receptors include Fcγl, Fcγll and Fcγlll receptors for immunoglobulin G (IgG) and CR1 and CR3 receptors for derivates of C3, a component of the complement cascade. The expression level of these recep¬ tors effects the ability of phagocytes to secrete the compounds meant for the defence of the organism. In in vitro tests it has been shown that immunologically activating compounds enable the two- or even threefold increase of the expression of complement receptors ( eino and Lilius, 1992, J. Leukocyte Biol., 51:157-163). In the same connection FcγRIII, which deviates from the other receptors mentioned in that it is not transmembraneous but attached on the surface of the cell by a glycosyl phosphatidyl inositol linkage (GPI), is easily detached, whereby its level is decreased into half. Further, it can be shown in vitro that cytokines, as gamma-interferon (IFNγ ), cause a substantial Fcγl-receptor expression in neutrophils. onocytes have this receptor even normally. FcγII-receptor seems to be fairly stable and constitutive on the basis of in vitro tests. However, it has to be noted that receptor expression and the binding ability of the receptors are not always one and the same thing. The above mentioned receptors can be activated or deactivated without their amount changing. That is why it is impor- tant to determine also the function of the cells. Brief description of the drawings Figure 1 Receiver operating characteristic (ROC) curve which shows the dependence of the indices of sensitivity and specificity on the selection of the cutoff point. Figure 2 Comparison of flow cytometric and luminomet- ric measurements; fluorescence intensity vs. magnitude of the luminescence signal in mil¬ livolts ( V). Description of the invention In the first series of experiments we studied the expres¬ sion of the above mentioned receptors in child patients with atopic dermatitis, having food allergy in the back¬ ground of the atopy. The values obtained were compared to the values of healthy children of the same age, and on the other hand child patients with an acute viral or bac¬ terial infection. We noticed that in the patients with infection the expression of all receptors has elevated compared to the healthy children statistically signifi¬ cantly both in neutrophils and monocytes. According to these results it seems that by atopic children the densi¬ ties of FcγRI and FcγRIII were decreased, but the density of FcγRII were increased in both neutrophils and monocy¬ tes compared to healthy children. However, these altera¬ tions are not statistically significant. The intensities of complement receptors (CR1 and CR3) have increased. On the basis of these observations it seems that the pha¬ gocytes of patients with allergy distinguish from the phagocytes of both healthy controls and those of the pa¬ tients with an acute viral or bacterial infection, and patients with allergy can be screened out easily. By de- termining the expression of complement receptors patients with allergy can be distinguished from healthy individu¬ als but not from patients with an infection, and by de¬ termining the expression of FcγRI, patients with allergy can be distinguished from patients with an infection. The present invention thus relates on one hand to a met¬ hod of detecting allergy in a patient, in which method CR1 and/or CR3 receptor expression of phagocytic cells is measured, and the values obtained are compared to the corresponding average values of healthy individuals, whe¬ reby the elevated expression values indicate the possible presence of allergy. Additionally, the Fcγl-receptor expression is measured to exclude infection. If the expression of this receptor is reduced compared to an infection control, the possibility of immune response caused by factors (as e.g. viruses or bacteria) other than allergic can be excluded. If desired, the Fcγlll receptor expression can also be measured in order to verify the result. The expression of this receptor seems also to be reduced in patients with allergy compared to the values obtained by patients with infection. In the second series of experiments the same study popu¬ lation was used as in the first experiment supplementing the atopic patients' group with 12 more patients. The ex¬ pression of said Fcγl, Fcγll, Fcγlll, CR1 and CR3 recep¬ tors in neutrophils and monocytes was measured in a si¬ milar manner. With the results obtained in this series of experiments a stepwise binary logistic regression ana- lysis was carried out to find a combination of variables which best describes the probability of allergy. As acute infections strongly affect receptor expression in both neutrophils and monocytes (as shown in the first series of experiments), to avoid diagnostic bias, children with acute infections were excluded from the analysis. Conse¬ quently, the results of logistic regression can be inter¬ preted and applied only when simultaneous acute infection is excluded. Stepwise binary logistic regression analysis of receptor variables showed significant and independent predictive effects for CR1 in neutrophils and FcγRI and FcγRII in monocytes (Table 1). Table 1. Binary logistic regression of receptor va¬ riables of allergy. In the model CRl is in neutrophils, and FcγRI and fcγRII are in mo¬ nocytes. Receptor Coefficient SE coefficient 95 UI e CRl 0.0415 0.017 1.04 1.01-1.08 FcγRI -0.0252 0.010 0.98 0.96-0.99 FcγRII 0.0334 0.013 1.03 1.01-1.06 intercept -4.40 1.76 0.012 0.0004-0.442 SE = standard deviation Cl = confidence interval The regression equation thus took the form of: Probability of allergy = (-(-4.40+0.0415*CRl-0.0252*FcγRI+0.0334*FcγRII)) 1+e where CRl is in neutrophils, and FcγRI and FcγRII are in monocytes. The model yields continuous results between 0 and 1, and the indices of sensitivity and specifity de¬ pend on the selection of the cutoff point as depicted in the receiver operating characteristic (ROC) curve in Fi- gure 1. The sensitivity and specificity of the logistic model were higher compared to the univariate techniques. If the cutoff point and probability of 0.70 is used, the model has a specificity of 82 % and a sensitivity of 80 %. Thus on the other hand the present invention relates to a method for determining the probability of allergy in a patient, which method comprises determining the CRl re¬ ceptor expression in neutrophils of a blood sample col- lected from the patient and determining the FcγI and FcγII receptor expressions in monocytes of said blood sample, comparing the values obtained with those of healthy individuals, the elevated CRl receptor expression on neutrophils and reduced FcγRI/FcγRII ratio in monocy- tes showing the probability of allergy. The probability of allergy can also be calculated using the regression equation given above. The receptor assays according to the methods of this in- vention are carried out e.g. using an immuno reaction with an antibody specific to each receptor using flow cytometric analysis. The method according to the invention is in general car- ried out by isolating phagocytic cells from a blood samp¬ le drawn from a patient, and measuring the expression of said receptors in them. The phagocytic cells can be iso¬ lated by osmotic lysis of erythrocytes of the blood samp¬ le by adding e.g. NH 4 C1, and washing the debris of the lysed erythrocytes and plasma out of the blood sample, whereby only leukocytes will be left. The amount of dif¬ ferent leukocyte types (neutrophils, monocytes) can be measured directly with e.g. flow cytometry. To measure the receptor expression the isolated leukocy¬ tes are labelled in cold (ca 4-5 °C) with a monoclonal antibody specific to the receptor in question. The anti¬ body is fluorescence labelled, or it will be labelled with a secondary fluorescence labelled antibody after being attached onto the surface of the cell. The fluores¬ cence intensity of each cell type is measured by flow cytometry. From the results the amount of each cell type is obtained, one pulse corresponding to one cell, and the amount of the receptor to be measured, as well as the percentage of the cells in which the receptor is present. However, flow cytometric receptor expression studies are relatively expensive and time-consuming, whereas lumino¬ metric assays are cheap and rapid. At best a luminometric assay can be effected of finger tip blood using a simple luminometer, the use of which does not demand noticeable laboratory expertise. This kind of method enables the screening of allergic patients e.g. in child health cent¬ res. Thus the receptor expression measurements can also be carried out luminometrically, whereby the leukocytes iso¬ lated as described above are labelled with the same mono¬ clonal antibodies as in flow cytometry, but now lumines¬ cence labelled, whereby the amount of receptors is ob- tained luminometrically as the magnitude on the lumines¬ cence signal (mV). A luminometric receptor expression assay is preferably carried out as follows: Isolated leukocytes (neutrophils or monocytes) are first labelled with a primary monoclo¬ nal antibody specific to the receptor to be measured. The mixture obtained is washed with a suitable buffer, and then it is incubated with a secondary antibody attached to an enzyme conjugate. A substrate to the enzyme conju- gate is added into the mixture, and the luminometric in¬ tensity is measured. All cells to which the antibody is attached give a light signal. A preferable enzyme conjugate for the present luminomet- ric assay is alkaline phosphatase, which is easy to use, and for which a stable substrate solution is available. In addition, to decrease the mV-response of the cell background the alkaline phosphatase of the leukocytes can be eliminated with a blocker. We have compared the flow cytometric and luminometric receptor assays in neutrophils using linear regression analysis, and the results obtained show good correspon¬ dence (Figure 2. ) The present invention relates further to a test kit for carrying out the methods according to the invention, the test kit comprising means for determining the expression of said receptors either by flow cytometry or lumino et- ry. For flow cytometric assay the test kit comprises antibo¬ dies specific to the receptors to be determined, a fluo¬ rescence label, and buffers necessary in the assay. For luminometric assay the test kit comprises primary antibodies specific to the receptors to be determined, secondary antibodies with an enzyme conjugate, a substra¬ te to the enzyme conjugate, and buffers necessary in the assay. In the following the preferred embodiments of the inven¬ tion are described. Two series of experiments were car¬ ried out, and the results obtained in said experiments are given. A specific example of carrying out the lumi¬ nometric assay is also given, as well as the comparative data of luminometric vs. flow cytometric assays. Experiment I Study population The study population comprised children aged 0 to 3 years being treated at Tampere University Hospital. The first control group comprised 17 children who had no infections or symptoms indicating allergy, and they were thus consi¬ dered to form the healthy controls in respect of this study (group A). The second control group consisted of 17 children, who had an acute infection in upper respiratory tract or another acute viral or bacterial infection, and they were thus considered to form the infection control group in this study (group B). The sick study subject group comprised 27 patients with atopic dermatitis and in the background thereof food allergy (group C). Collection and preparation of blood samples Venous blood samples were collected both from control and test subjects in test tubes without EDTA. In the blood coagulated during transport erythrocytes were lysed with 0.83% ammonium chloride for 10 min at room temperature, and centrifuged (400 x g, 10 min, 4 °C). The leukocyte pellet was suspended in ice cold Ca 2* - and g 2* -free Hank's balanced salt solution (CMF-HBSS) and kept on ice until used in the receptor studies. Measurement of receptor expression The expression of CRl, CR3, Fcγl, Fcγll and Fcγlll recep¬ tors in neutrophils and monocytes were measured by flow cytometry as described by Leino and Lilius ( supra ) . Briefly, aliquots of leukocyte suspension were labelled with anti-CRl, anti-CR3 (Becton-Dickinson, Mountain View, CA), anti-FcγRI, anti-FcγRII and anti-FcγRIII (Medarex Inc., West Lebanon, NH., U.S.A.) monoclonal antibodies for 30 min at 4 °C. The control samples were labelled with monoclonal antibodies risen against irrelevant anti¬ gens. Flow cytometric analysis was performed with a FACS- can (Becton-Dickinson) flow cytometer. The laser excita¬ tion wavelength was 488 run and the fluorescence of fluo- rescein isothiocyanate (FITC) was measured at 520 nm and that of phycoerythrine (PE) (anti-CR3-antibody) at 580 nm. The fluorescence of 5000 cells was measured, about 4500 of which were neutrophils and about 500 monocytes. Statistics ANOVA + the test for paired values were used in comparing the differences in the values of the patient and control groups. P<0.05 was considered significant. Results In Table 2. the values obtained by flow cytometry are given (fluorescence intensity) for each receptor in neut¬ rophils, and in Table 3. in monocytes. The values mean average amounts of receptors per cell or the percentage (%) of the cells where the receptor is expressed, respec¬ tively. Table 2. The average amount (fluorescence intensity) or percentage (%) of CRl, CR3, FcγI, FcγII and Fcγlll receptors in neutrophils in healthy controls (A), controls with infection (B) and atopic patients (C). p = statistical significance. Receptor A t sd B t sd C i sd P (A,B) P (B.C) P (λ,C) CRl 60 ± 21 86 ± 39 82 ± 20 0.01992 0.62815 0.00259 CR3 589 t 262 758 ♦ 264 842 t 227 0.08059 0.28898 0.00174 t FcγRI (%) 46 + 30 80 i 28 45 ± 25 0.00178 0.0001 0.84854 FcγRI intensit. 27 ± 16 55 ± 41 21.10 0.0118 0.00029 0.19124 FcγRII 126 t 25 218 i 71 143 i 26 0.00003 0.00002 0.04377 FcγRIII intensit. 883 i 284 925 ♦ 314 690 t 209 0.68303 0.00519 0.1421 Table 3. Average amount (fluorescence intensity) or percentage (%) of CRl, CR3, FcγI, Fcγll and Fcγlll receptors of monocytes in healthy controls (A), controls with infection (B) and atopic patients (C). p = statistical significance. Receptor A i sd Bi sd Ci sd P (A.B) P (B.C) P (A,C) CRl 76 ± 29 96 ± 30 97 ± 22 0.05728 0.87861 0.01198 CR3 717 i 380 1008 i 442 952 i 211 0.05443 0.585 0.01271 FcγRI intensit. 102 + 56 159 t 80 85 ± 35 0.02265 0.00021 0.23057 FcγRII 129 i 40 213 ♦ 88 162 i 29 0.00125 0.0099 0.00444 FcγRIII (%) 31 ± 19 42 ± 17 42 ± 14 0.07247 0.99068 0.031 FcγRIII intensit. 158 i 134 198 i 97 132 i 71 0.40888 0.02368 0.39837 Experiment II Study subjects and design Study subjects were partly the same children as in the Experiment I. To the atopic dermatitis group 12 objects were added. Three groups of children aged 1 to 55 months, mean 14 months, were studied with their parents' consent: (1) 39 atopic dermatitis patients, (2) 17 age-matched patients with an acute infection, and (3) 17 age-matched healthy children. The study was approved by the Ethical Committee of Tampere University Hospital. The atopic dermatitis group comprised 39 children aged 1 to 55 (mean age 11 months) fulfilling the Hanifin crite- ria (Hanifin, J.M. , 1987, Monogr. Allergy, 21:116-131) for atopic eczema in children. They had been referred to a pediatric clinic on the basis of suspected food allergy and were allocated to double-blind placebo controlled or open cow milk challenge as described previously (Iso- lauri, E. and Turjanmaa, K., 1996, J. Allergy Clin. Im¬ munol., 97:9-15). The inclusion criteria for the study was that the patient be free of symptoms and signs of acute infection and had not received any medication du¬ ring the previous month. None of the patients was re- ceiving systemic corticosteroid therapy. Blood samples for the receptor studies were collected at the presenta¬ tion. The second group included patients, aged 1 to 37 (mean age 16) months, who were admitted for acute respiratory infections or acute gastroenteritis, septicaemia or uri¬ nary tract infection. Blood samples were collected during the first 12 hours in hospital. The third group comprised children, aged 1 to 38 (mean age 16) months, who were studied as outpatients for minor operations or previous investigations. All were found healthy. The criteria for enrollment were no acute infec¬ tions for the previous month and no history of atopy or food allergy in the family. Collection and preparation of blood samples Peripheral, EDTA-anticoagulated (1.5 mg EDTA/1 ml of blood) blood samples were collected from the study sub¬ jects. Blood erythrocytes were lysed with 0.83% ammonium chloride at 20 °C for 15 min. After lysation leukocytes were centrifuged (400 x g for 10 min at 4 °C) and resus¬ pended in ice-cold CMF-HBSS. Measurements of receptor expression Leukocytes (3xl0 5 ) were incubated with monoclonal antibo- dies in 12x75 mm polystyrene vials for 30 min at +4 β C. Incubation volume was 90 μl. Control sample was incubated with isotype matched monoclonal antibodies directed to irrelevant antigen. After incubation cells were washed with cold CMF-HBSS. Leukocytes were resuspended in 500 μl of cold CMF-HBSS and they were ready to flow cytometry examination. Flow cytometry Flow cytometric analysis was performed with FACScan (Bec- ton Dickinson, Mountain View, CA, USA) flow cytometry with an argon ion laser. The laser excitation wavelength was 488 nm. Emitted light was collected through a 560 n and 600 nm dichromic filter and through 530 nm and 585 nm bandpass filters. The fluorescence of 5000 cells was mea- sured using logarithmic amplification. A relative measure of receptor expression was obtained by determining the mean log fluorescence intensity. The percentage of posi¬ tive cells was generally 98-100 unless otherwise indica¬ ted. Statistics The data in Tables 4 and 5 are given as medians with low¬ er and upper quartiles. The Kruskal-Wallis test with pai¬ red contrasts was used for comparing differences between groups. Level of significance was <0.05. A stepwise lo¬ gistic regression analysis was done to identify the best combination of receptors for detecting atopic dermatitis and food allergy. The probability of atopic sensitization estimated by the logistic model was then used as a new diagnostic variable. A child with the estimated probabi¬ lity higher than the specific cutoff points can be esti¬ mated and classified as allergic. The indices of sensiti¬ vity and specificity for positive and negative test re¬ sults were calculated using the receiver operating cha- racteristic (ROC) curve (see Figure 1). Results With the second larger group of patients we could subs- tantially confirm the results as regards the receptor expressions obtained in the first experiment. However, it was established that in fact in allergic patients none of the receptor expressions were significally reduced com¬ pared to those of healthy individuals. This finding de- viates somewhat from the results obtained in the first experiment. The children with acute infections had on the average higher receptor expression in both neutrophils (Table 4) and monocytes (Table 5) compared to healthy controls. With the exception of the frequency of CR3 in neutro¬ phils, and CRl and CR3 in monocytes, and FcγRIII in neut¬ rophils and monocytes the differences were statistically significant. The patients with atopic dermatitis had higher complement receptor CRl expression compared to healthy controls. By contrast, the frequency of receptors for IgG was indis¬ tinguishable from that in healthy controls (Tables 4 and 5). The expression of FcγRI and FcγRII in neutrophils and in monocytes, and FcγRIII in monocytes was significantly lower in patients with atopic dermatitis and food allergy than those with acute infections (Tables 4 and 5). Using a logistic regression model we could show (see the regression equation above), that the combination of va- riables which best describes the probability of allergy, is CRl in neutrophils and FcγRI and FcγRII in monocytes. It thus seems, that in atopic sensitization, as deter¬ mined in this study by a logistic regression analysis, the distinctive pattern of receptor expression is eleva- ted CRl on neutrophils and reduced FcγRI/FcγRII ratio in monocytes. The results obtained in these experiments suggest that a distinct receptor profile of phagocytic cells can be cha- racterized in atopic dermatitis patients with food aller¬ gy, providing a new direction to the search for early identification of children predisposed to allergic sensi¬ tization. Table 4. Fcγ and CR receptor expression of neutrophils, median (lower quartile-upper quartile), in healthy controls, disease control patients with acute infections, and in children with atopic dermatitis and food allergy. Receptor Healthy controls (n=17) Infection controls (n=17) Atopic dermatitis (n=39) Kruskal-Wallis test CRl 63 (38-78) 87 (54-114) 87 (61-101) p = 0.008 CR3 680 (300-844) 772 (580-982) 780 (468-1003) p = 0.12 FcγRI 21 (15-37) 42 (23-74) 22 (15-26) p = 0.006 CO FcγRII 124 (107-147) 222 (157-266) 144 (112-160) p = < 0.0001 FcγRIII 842 (725-990) 850 (705-1098) 630 (524-874) p = 0.03 Table 5. Fcγ and CR receptor expression of monocytes, median (lower quartile-upper quartile), in healthy controls, disease control patients with acute infections, and in children with atopic dermatitis and food allergy. Receptor Healthy controls (n=17) Infection controls (n=17) Atopic dermatitis (n=39) Kruskal-Wallis test CRl 71 (60-91) 92 (68-104) 85 (77-101) p = 0.12 CR3 737 (300-1038) 1003 (709-1272) 813 (501-1028) p = 0.19 FcγRI 86 (68-138) 133 (103-194) 72 (57-113) p = 0.0006 sO FcγRII 139 (97-152) 203 (165-226) 147 (126-185) p = 0.0005 FcγRIII 114 (89-148) 197 (120-253) 113 (93-164) p = 0.04 Luminometric assay and comparison thereof with flow cyto¬ metric assay CRl, CR3, FcγRI, FcγRII and FcγRIII receptor expressions in isolated neutrophils were measured by luminometry as follows. Neutrophils (3xl0 5 ) were incubated with 0.5 μg of primary monoclonal antibodies (CD35 for CRl: CLB, Amsterdam, Hol- land; CDllb for CR3, CD64 for FcγRI, CD32 for FcγRII and CD16 for FcγRIII: PharMingen, San Diego, CA, USA) in po¬ lystyrene vials for 30 min at 4 °C. Incubation volume was 50 μl. After incubation the cells were washed with 500 μl of cold CMF-HBSS (containing 0.1 % Na-azide). The cells were incubated on ice for 30 min with secondary antibo¬ dies (AP-F(ab') 2 Rabbit anti-mouse IgG (H+L), Zy ed, San Francisco, CA, USA) conjugated to alkaline phosphatase (AF) . The mixture was then washed three times with CMF- HBSS buffer as above, and the substrate solution (AMPPD, Tropix, Bedford, MA, USA) was added. While AMPPD is de¬ graded by alkaline phosphatase, light measurable by lu¬ minometry is emitted. The amount of the light is propor¬ tional to the amount of the enzyme and thereby to the amount of the primary antibody attached to the receptor. A blocker (Levamisole solution, Zymed) was used to eli¬ minate the alkaline phosphatase included in the cells. LKB Wallac 1251 luminometer (Turku, Finland) was used. To compare the results on the luminometric assay to the flow cytometric assay, a flow cytometric assay was car¬ ried out using the same unlabelled monoclonal anti-recep¬ tor antibodies than in the luminometric assay. The anti¬ bodies were detected on the cell wall using a FITC-label¬ led secondary antibody (FITC-Goat anti-mouse IgG (H+L), Zymed). Fluorescence intensities were measured as descri¬ bed in the paragraph "Flow cytometry" above. The comparative results are given in Table 6. Table 6. Comparison of luminometric (LM) and flow cy¬ tometric (FC) assays. Receptor Receptor Signal A amount* FC(FI) LM(mV) CRl 7000-40000 16.3 50.2 10000 CR3 17000-65000 35.9 123.6 25000 FcγRI <1000 5.6 28.6 5700 FcγRII 10000-60000 46.2 184.7 37000 FcγRIII 100000-300000 140.5 583.4 120000 number of receptors per cell, values given in litera¬ ture number of receptors as calculated on the basis of the number of cells used in the luminometric assay, mat¬ ching well with the literature values FI = fluorescence intensity V = millivolts Background: Cells + anti-mouse-FITC: intensity 2.1 Cells + anti-mouse-AF: 12.6 mV Comparison of the two assay methods by linear regression analysis showed that the luminometric assay gives results comparable to those obtained in flow cytometric assay (Fig. 2).

Claims: We claim 1. Method for detecting allergy in a patient, in which method the possible presence of allergy is shown by 1 ) determining in a blood sample collected from the pa¬ tient the CRl and/or CR3 receptor expression of phagocy¬ tic cells, and 2) further determining the FcγI receptor expression in said cells, and 3) comparing the CRl and CR3 receptor expression values obtained to corresponding average values of healthy indi¬ viduals, and 4) comparing the FcγI receptor expression value obtained to corresponding average values of patients with an acute infection, the elevated CRl and CR3 values and the reduced FcγI receptor expression value showing the possible presence of allergy. 2. Method according to claim 1 wherein the Fcγlll recep¬ tor expression is also determined. 3. Method according to claim 1 or 2 wherein the assay is performed by immunoreaction with an antibody specific to the receptor. 4. Method according to claim 3 wherein the assay is per¬ formed fluorimetrically. 5. Method according to claim 3 wherein the assay is per¬ formed luminometrically. 6. Method according to any one of the claims 1 to 4, comprising collecting a blood sample from a patient, separating leukocytes from erythrocytes and plasma with conventional techniques, labelling leukocytes with a fluorescence labelled monoclonal antibody specific to the receptor to be measu¬ red, and determining in neutrophils and monocytes the expres- sion of said receptors by flow cytometry by measuring fluorescence intensity thereof. 7. Method according to any one of claims 1 to 3 or 5 com¬ prising collecting a blood sample from a patient, separating leukocytes from erythrocytes and plasma with conventional techniques, labelling leukocytes with a primary monoclonal anti¬ body specific to the receptor to be measured, incubating the labelled leukocytes with a secondary antibody and an enzyme conjugate, adding into the solution a substrate of the enzyme, and determining from the leukocytes the expression of said receptors by luminometry by measuring luminescence intensity thereof. 8. Test kit for carrying out the method according to claim 1, comprising antibodies specific to CRl and/or CR3 receptors and FcγI receptor, a fluorescence label and buffers necessary in a flow cytometric assay. 9. Test kit for carrying out the method according to claim 1, comprising primary antibodies specific to CRl and/or CR3 receptors and FcγI receptor, a secondary anti¬ body with an enzyme conjugate, a substrate, and buffers necessary in a luminometric assay. 10. Method for determining the probability of allergy in a patient, comprising 1 ) determining the CRl receptor expression in neutro¬ phils of a blood sample collected from the patient, and 2) determining the Fcγl and Fcγll receptor expressions in monocytes of said blood sample, and 3) comparing the values obtained with those of healthy individuals, the elevated CRl receptor expression on neutrophils and reduced FcγRI/FcγRII expression ratio in monocytes showing the probability of allergy. 11. The method according to claim 10, wherein the proba¬ bility of allergy is further calculated using the regres- sion equation: Probability of allergy = (-(-4.40+0.0415*CRl-0.0252*FcγRI+0.0334*FcγRII)) 1+e where CRl is in neutrophils, and FcγRI and FcγRII are in monocytes. 12. The method according to claim 10, wherein the recep¬ tor expressions are determined by flow cytometry. 13. The method according to claim 10, wherein the recep¬ tor expressions are determined by luminometry. 14. Test kit for carrying out the method according to claim 12, comprising antibodies specific to CR1-, Fcγi- and FcγII-receptors, a fluorescence label and buffers ne¬ cessary in a flow cytometric assay. 15. Test kit for carrying out the method according to claim 13, comprising primary antibodies specific to CR1-, Fcγl- and FcγII-receptors, a secondary antibody with an enzyme conjugate, a substrate, and buffers necessary in a luminometric assay.

Inventors: ISOLAURI ERIKA, LILIUS ESA-MATTI, SALMINEN SEPPO, ISOLAURI, ERIKA, LILIUS, ESA-MATTI, SALMINEN, SEPPO
Applicants: ABOATECH AB OY, ISOLAURI ERIKA, LILIUS ESA MATTI, SALMINEN SEPPO, ISOLAURI, ERIKA, LILIUS, ESA-MATTI, OY ABOATECH AB, SALMINEN, SEPPO
Application year: 1996
Main classification: G01N33
IPC codes: G01N33