Detection of antigen and antibody in childhood tuberculous meningitis

Objective Mycobacterium tuberculosis excretory secretory 31 kDa, a serine protease antigen (M. tb ES-31), prepared fromMycobacterium tuberculosis H₃₇Ra culture medium has been shown to have potential in detecting tuberculosis. Precise diagnosis and management of tuberculous meningitis, in children in particular, is essential to curtail mortality and morbidity. Methods In this study, M. tb ES-31 antigen, was used in Indirect ELISA to detect tuberculous IgG antibody, in sera and CSF samples while affinity purified anti ES-31 goat antibody was used in sandwich ELISA for detection of tuberculous antigen. In sixty-five samples each of CSF and sera from cases with neurotuberculosis and control with non-tuberculous diseases were collected from Kasturba Hospital, Sevagram. Results Among the 20 patients suffering from neurotuberculosis the IgG antibody was detected in 17(85%) of CSF and 16(80%) of sera samples, while antigen was detected in 18 (90%) in CSF and 16 (80%) in sera. Overall specificity of the assay for both IgG antibody and antigen detection in CSF was 96% while in sera it was 94% for IgG antibody and 96% for antigen detection. Conclusion This study showed the usefulness of mycobacterial serine protease antigen and its antibody in detecting neurotuberculosis.     

A study of tubercular antigen and antibody in childhood tuberculosis.

A radioimmunoassay for the detection of tubercular (TB) antigen (Ag) and antitubercular antibody (Ab) was evaluated for the serodiagnosis of childhood tuberculosis. Children with primary complex, progressive primary complex, miliary tuberculosis, and calcified lung lesions without clinical evidence of active tuberculosis were studied. Significantly elevated levels of TB Ag and TB Ab isolated from the circulating immune complexes were obtained in primary, progressive primary, and miliary tuberculosis patients as compared to controls (P less than 0.01). The majority of patients with calcified lung lesions and without active tuberculosis demonstrated high levels of antibody. It was observed that elevated levels of TB Ag and/or antibodies were present in 54 per cent of patients with primary complex, 94 per cent of patients with progressive disease and 69 per cent of patients with miliary tuberculosis. It is possible that is suspected patients with the above mentioned diseases, a diagnosis can be established by using these techniques.     

Sero diagnosis of tuberculosis in children using two ELISA kits

The diagnosis of childhood tuberculosis is based on circumstantial evidence in the absence of a gold standard in the majority of cases. Sero-diagnosis offers scope for an early diagnosis in a variety of clinical conditions and is simple to perform. A number of mycobacterial antigens have been used for antibody detection assays and several are available as kits in the market. This study was done to evaluate the value of antibody detection kits (ELISA) against the A60 antigen and 38 kDa antigen of Mycobacterium tuberculosis in the diagnosis of childhood tuberculosis at the outpatient department of the Institute of Social Paediatrics, Government Stanley Hospital in collaboration with Tuberculosis Research Centre, Chennai. Thirty five children with pulmonary tuberculosis, 7 with TB lymphadenitis and 22 healthy controls were studied. In addition to routine investigations including gastric lavage for AFB culture, serum antibodies against the A60 and 38 kDa antigens were assayed using commercially available ELISA kits. With A60, IgM serum levels were positive in 74% of pulmonary TB cases, 57% of TB lymphadenitis cases and 50% of controls. A60 IgG was positive in 17% of pulmonary TB, 86% of TB lymphadenitis and 14% of controls. The 38 kDa IgG antibody was positive in 37% of pulmonary and 86% of TB lymphadenitis cases and 27% of controls. Among 10 culture confirmed cases, A60 IgM was positive in 8, A60 IgG in 3 and 38 kDa IgG in 5 patients. The sensitivity of the tests ranged between 29% and 71% and specificity between 50% and 86%. Although the numbers are small, the results suggest that serodiagnosis using the currently available antigens of M. tuberculosis is unlikely to be a confirmatory test for tuberculosis in children.     

Heterophile antibody positive infectious mononucleosis

Objective: The present study has been carried out to analyse the trend of heterophile antibody positive infectious mononucleosis cases.Methods: A total of 1741 cases of clinically suspected infectious mononucleosis from various age groups were investigated during the period January, 1986 to December, 2000 and were analysed for infectious mononucleosis (IM) specific heterophile antibody by Paul-Bunnel-Davidsohn (PBD) test. Forty seven heterophile antibody negative samples were also tested simultaneously for the presence of the IgG antibody to viral capsid antigen (VCA) and Epstein Barr nuclear antigen (EBNA) to detect the exposure to Epstein Barr Virus (EBV) infection.Results : The overall percentage of EBV specific heterophile (Paul-Bunnel) antibody positivity was found to be 11.1 % (194/1741). The average Paul-Bunnel antibody positivity between 1986 to 1990 was 20.5% which declined drastically to 5.7% during 1991-2000. Males comprised of 55.2% of the serologically proven IM cases. Of the 47 heterophile antibody negative cases, 38 (80.9%) and 33 (70.2%) were found to be positive for anti-VCA IgG and anti-EBNA IgG antibodies respectively. Paul Bunnel antibody positivity was found to be higher in > 14 year⁵ age group patients than those below 14 years.Conclusion : These findings suggest that the EBV infection still continues to be endemic in this part of the country, however, a declining trend in IM cases was observed during the last decade.     

Serological diagnosis of tuberculosis

Objective  To evaluate the efficacy of ELISA for the detection of IgG antibodies against antigen 85 complex (Ag 85 complex) of Mycobacterium tuberculosis. Methods  Children of either sex, 0-18 years of age, attending the outpatient department and admitted in the casualty and wards of the Department of Pediatrics, S.N. Medical College, Agra, were included in present study. The study was carried out on children with pulmonary and CNS tuberculosis along with matching controls (83 cases and 32 controls). Informed consents of their parents or guardians were taken. They were subjected to clinical examination, relevant laboratory investigations, tuberculin test and chest radiograph. Relevant body fluids were subjected to bacteriological tests; ELISA was applied to serum samples for detection of IgG antibodies against antigen 85 complex (Ag85). The result of ELISA was compared with bacteriological tests [Ziehl Neelson (ZN) staining for acid-fast bacilli, culture on Lowenstein Jensen (LJ) medium and culture on BacT/Alert 3D system]. Results  ELISA tests showed a significantly higher sensitivity (59.1%) as compared with LJ medium culture method (19.3%), BacT/Alert 3D system (24.1%) and ZN staining (16.9%) in all patients (p<0.001). Specificity of ELISA test was 71.9%. Conclusion  In view of the convenience, low cost and good sensitivity, ELISA tests have a promising future in the diagnosis of childhood tuberculosis.     

Diagnosis of tuberculous meningitis by detection of antigen and antibodies in CSF and sera

OBJECTIVE: To evaluate diagnostic potential of three immunological tests, namely, detection of H37Rv antigen of M. Tuberculosis in CSF, detection of antibodies (IgG) against H37Rv in CSF and detection of antibodies (IgG) against H37Rv in serum for diagnosis of tuberculous meningitis in children. SUBJECTS: 50 children diagnosed as patients of tuberculous meningitis were included as cases and 48 children with CNS diseases of nontubercular etiology [pyogenic meningitis (n = 31), encephalitis (n = 10), seizure disorder of unknown etiology (n = 5), brain tumor (n = 2)] served as controls. METHODS: H37Rv antigen of M. tuberculosis was detected in CSF by Dot ELISA, and antibodies (IgG) against H37Rv in CSF and serum were detected by Plate ELISA. RESULTS: Detection of H37Rv antigen in CSF was the most sensitive (90%) and specific (95.83%) with positive and negative predictive values of 95.74% and 90.19%, respectively, followed by detection of antibodies in CSF (sensitivity-74%, specificity-89.58%, positive predictive value-88.10%, negative predictive value-76.78%). Detection of antibodies in serum had low sensitivity (50%), specificity (91.67%), positive predictive value (86.21%) and negative predictive value (63.76%). CONCLUSIONS: Detection of antigen in CSF is a rapid, sensitive and specific test for diagnosis of tuberculous meningitis in children. Detection of antibody in CSF may be useful in some cases but needs further evaluation. Detection of antibody in serum does not appear to be useful for diagnosis of tuberculous meningitis.     

Serologic response to a secreted and a cytosolic antigen of Mycobacterium tuberculosis in childhood tuberculosis.

BACKGROUND AND AIM: Bacteriologic diagnosis of childhood tuberculosis is difficult, and alternate methods are needed. The utility of a serologic test for major secretory antigen (30 kDa) and a cytosolic antigen (16 kDa) of Mycobacterium tuberculosis was evaluated for the diagnosis of tuberculosis in children. METHODS: Enzyme-linked immunosorbent assay was used. Specific IgG, IgA and IgM antibodies were measured in the sera from 26 clinically and/or bacteriologically diagnosed cases of childhood tuberculosis and 61 normal children. RESULTS: Anti-IgG antibodies alone, against both 30- and 16-kDa antigens, were detected in 65.4% of patients. However, by combination of all three isotypes, increased sensitivities of 84.6 and 73%, with a specificity of 96.7% each, were obtained for 30- and 16-kDa antigens, respectively. CONCLUSIONS: We found good specificity and reasonably good sensitivity for detection of antibodies by enzyme-linked immunosorbent assay to 30-kDa antigen alone. The 16-kDa antigen did not perform as well.     

Antifilarial and anti PPD IgM antibodies in cord blood

Tuberculosis and Filariasis are commonly encountered in South India, more so in the low socio-economic group. This study was undertaken to find out the fetal immune response to maternal filariasis and tuberculosis. The presence of anti-filarial and anti-PPD IgG and IgM antibodies in the mother and cord blood at the time of delivery was identified by ELISA. Six out of 29 cases showed IgM against PPD in the cord blood and 7 out of 29 cases showed IgM againstBrugia malayi antigen in the cord blood. In both instances, 6 out of 29 for PPD and 7 out of 29 for B.malayi, the maternal blood too showed the presence of IgM to these two antigens. Comparison with anti-Ascaris lumbricoides IgM antibodies in mother and cord blood in these (6 out of 29 against PPD and 7 out of 29 against S.malayi) cases did not show a similar distribution of IgM antibodies in mother and cord blood, indicating that there is a fetal response to maternal filariasis and tuberculosis.     

Development of immunoglobulin G subclass antibodies to ovalbumin,birch and cat during the first eight years of life in atopic and non-atopic children

Immune responses to allergens in young children include both Th1- and Th2-like immunity, which may regulate the secretion of immunoglobulin (Ig) G subclass antibodies differently. The time, route and level of exposure to an allergen may be decisive with regard to whether sensitization or tolerance will ensue. To study this, we investigated the development of IgG subclass antibodies to food and inhalant allergens during childhood. The study group comprised a cohort of 96 children participating in a prospective study. IgG subclass antibodies to ovalbumin, Bet v 1 and cat dander were analyzed at birth, 6 and 18 months and 8 years by ELISA. IgG₁ and IgG₃ subclass antibodies to ovalbumin peaked at 18 months and then declined up to 8 years of age, whereas antibodies to the inhalant perennial allergen cat, but not the inhalant seasonal allergen birch, increased with age. Exposure to cat and birch tended to be associated with high antibody levels to those allergens, whereas antibody levels to ovalbumin were not related to exposure to egg. The presence of positive skin prick tests and circulating IgE antibodies correlated with high levels of IgG subclass antibody responses to the allergens. Atopic symptoms were associated with high levels of IgG subclass, particularly IgG₄, antibodies to the allergens. The difference in antibody levels between atopic and non-atopic children was most marked at 6 months for ovalbumin. For the seasonal inhalant allergen birch, the difference was apparent from 18 months, whereas a difference in antibody levels to the perennial inhalant allergen cat was already present at 6 months. In conclusion, IgG subclass antibodies to food allergens peak in early infancy and are then down-regulated, whereas antibodies to the inhalant perennial allergen cat, but not the inhalant seasonal allergen birch, increase with age. Atopy is associated with high levels of IgG subclass, particularly IgG₄, antibodies to allergens, supporting a deviation of the immune system towards Th2-like responses in atopic children.     

Serodiagnosis of Helicobacter pylori infection is not accurate for children aged below 10

BACKGROUND: In order to investigate the immune response to Helicobacter pylori in childhood, we compared anti-H. pylori IgG and IgA antibodies with H. pylori antigen in the stool and examined the clinical usefulness of the anti-H. pylori IgG and IgA antibodies. METHODS: This study included 157 children who were seen at our hospital. Serum and stool samples were obtained for these children. Antibodies to H. pylori were examined using an H. pylori IgG enzyme-linked immunosorbent assays (ELISA) and an H. pylori IgA ELISA. Analysis of stool samples was carried out by the H. pylori stool antigen (HpSA) enzyme immunoassay. RESULTS: Of the 157 children, 45 children were HpSA positive, 110 were negative and two were undetermined. Out of 45 HpSA positive patients, 25 children were both IgG and IgA positive and seven were negative for both IgG and IgA antibodies. Of the 110 patients who were HpSA negative, 97 were negative for both antibodies. All HpSA positive children older than 10 years were positive for IgG and IgA antibodies, but of the HpSA positive children under the age of 10, only 18 out of 35 (51.4%) were positive for IgG antibodies or IgA antibody. CONCLUSION: These facts suggested that an immature immune response or tolerance to H. pylori exists in childhood and serodiagnosis of H. pylori infection is less useful in children aged below 10.     

Increased frequency of IgM antibodies to cow's milk proteins in Hungarian children with newly diagnosed insulin-dependent diabetes mellitus

We investigated the association between serum antibodies to cow’s milk proteins and insulin-dependent diabetes mellitus (IDDM) in Hungarian children. Forty-eight children 1.0–17.1 years of age with newly diagnosed IDDM and 74 control children 1.0–16.0 years of age were studied for serum IgG, IgA and IgM antibodies to cow’s milk, β-lactoglobulin, bovine serum albumin and ovalbumin by enzyme-linked immunosorbent assays. The specificity of IgM antibodies to β-lactoglobulin and bovine serum albumin was controlled by Western blot. The levels of IgG and IgA antibodies to cow’s milk proteins were similar in children with and without IDDM, with the exception of slightly increased levels of IgA antibodies to β-lactoglobulin in diabetic children (P = 0.05). The levels of IgM antibodies to cow’s milk were significantly higher in IDDM patients than in control children (P = 0.0002). Children with IDDM more often had IgM antibodies to β-lactoglobulin (46.3% vs 18.8%; P = 0.002) and bovine serum albumin (87.8% vs 49.3%, P < 0.0001) than control children. Neither the levels of IgG or IgA antibodies to ovalbumin nor the frequency of IgM antibodies to ovalbumin differed between diabetic and control children. Conclusion In Hungarian children, clinical manifestation of IDDM is often associated with IgM antibody response to cow’s milk protein and its fractions, β-lactoglobulin and bovine serum albumin, indicating a loss of immunological tolerance to these proteins. IgG and IgA antibodies to cow’s milk proteins, associated with an early introduction of cow’s milk in diet, seem to play a minor role in the development of childhood IDDM in Hungary. Received: 14 November 1995 Accepted: 3 March 1996     

Immune complexes and Pseudomonas aeruginosa antibodies in cystic fibrosis.

Serum samples from 57 patients with cystic fibrosis were tested for the presence of IgG, IgA, IgM, IgE, and circulating immune complexes containing IgG, IgA, and IgM. Titres of class specific antibodies to Pseudomonas aeruginosa, and class specific antibodies to Ps aeruginosa in circulating immune complexes, were also measured. According to the Shwachman score the patients were divided into three clinical groups: group 1-moderate and severe disease, group 2-mild disease, and group 3-well. The results of the immunological investigations were correlated with the clinical state of the patients as assessed by the Shwachman score. Serum concentrations of IgG, IgA, and IgM were inversely correlated with the Shwachman score, but the differences between the groups were only significant for IgG and IgA. The same correlations were found for circulating immune complexes containing IgG and IgA. Antibodies to Ps aeruginosa could be detected in most of the patients'' serum samples. IgA antibody specific to Ps aeruginosa was the most often raised, even in patients in group 3. It is therefore suggested that IgA antibody specific to Ps aeruginosa could be an early marker of colonisation by Ps aeruginosa and a sensitive measurement of infection with Ps aeruginosa in young children with cystic fibrosis. Moreover, in the circulating immune complexes, class specific antibodies to Ps aeruginosa were found in nearly half the patients. The highest titres of IgG and IgA antibodies specific to Ps aeruginosa in the circulating immune complexes were detected in the patients with the worst clinical state (group 1).     

Keith Edwards score for diagnosis of tuberculosis

Objective : To evaluate the applicability of Keith Edwards scoring system for the diagnosis of childhood tuberculosis.Methods. One hundred and one children aged 2 months to 12 years who fulfilled the inclusion criteria were evaluated with Keith Edwards score. The diagnosis of tuberculosis by Keith Edwards score and the definitive reference were compared.Results. Among the 65 children diagnosed as having tuberculosis by the definitive reference, 59 had a Keith Edwards score of >7. Four children had a score of >7 but were not suffering from tuberculosis. The sensitivity and specificity of this score have been found to be 91% and 88% respectively.Conclusion. In select population with indicative clinical features, Keith Edwards score can be a definitive guideline for the diagnosis of childhood tuberculosis. However, more studies are required for the validation of this clinical score before it can be used as a definitive diagnostic reference standard for tuberculosis.     

Impact of treatment reduction for childhood acute lymphoblastic leukemia on serum immunoglobulins and antibodies against vaccine-preventable diseases

Background

The consequences of current intensive chemotherapy for childhood acute lymphoblastic leukemia (ALL) for immune defense are a matter of concern. The purpose of this study was to examine the effect of reduced compared with intensive (conventional) ALL chemotherapy on serum immunoglobulin levels and specific antibody concentrations against vaccine‐preventable diseases.

Procedure

Patients treated according to Dutch Childhood Oncology Group ALL 10 protocol were stratified by minimal residual disease to receive reduced (standard risk; SR) or intensive (medium risk; MR) intensification/maintenance treatment. Between November 2004 and July 2009 we compared serum immunoglobulins of 110 patients and specific antibodies against diphtheria toxin, tetanus toxin, and Bordetella pertussis antigens of 41 patients of SR and MR groups during chemotherapy.

Results

Immunoglobulin levels showed significantly different patterns between the SR and MR groups. In the MR group IgG, IgA, and IgM levels decreased towards the end of intensive treatment; in the SR group IgG levels increased while IgA and IgM stabilized. In both groups IgM and IgG levels were most affected. Specific antibody levels against vaccine‐preventable diseases decreased in both groups, but more profound in MR group.

Conclusions

Although reduced chemotherapy is beneficial for immunoglobulin level recovery and might prevent susceptibility for infections, specific antibodies remain decreased. Pediatr Blood Cancer 2012; 58: 701–707. © 2011 Wiley Periodicals, Inc.     

Serum IgG levels to bovine insulin in type I diabetes mellitus

Objectives: This study was undertaken to determine humoral immune response to bovine insulin in Iranian children with type 1 diabetes mellitus.Methods: Serum samples were taken from 93 children aged 4–17 years with type I diabetes mellitus from two centers in Iran (the Iranian Association of Diabetes in Tehran and Center for Diabetes Research in Hamedan), 17 apparently healthy siblings of the diabetic patients (related controls), 28 apparently healthy age- and sex-matched controls (unrelated controls), 14 patients aged 11–15 years with auto-immune thyroiditis, and 45 patients with type II diabetes (aged 44–68 years). Samples were then examined for specific IgG to bovine insulin by enzyme-linked immunosorbent assay (ELISA). A questionnaire on medical history, duration of exclusive and non-exclusive breast feeding and daily intake of dairy products was completed before bleeding.Results: Duration of exclusive and non-exclusive breast-feeding showed no significant difference between patients with type I diabetes, related and unrelated controls and thyroid patients. Diabetic children, however, had significantly higher serum levels of anti-bovine insulin IgG than did unrelated and related healthy controls and patients with type II diabetes (P < 0.01). There was no significant difference between healthy siblings of diabetic children and unrelated controls. In type I diabetic patients and their healthy siblings, serum levels of IgG to bovine insulin were inversely correlated with the duration of non-exclusive breast feeding (r_s= -0.37, P= 0.016 and r_s -0.53, P= 0.049, respectively). There was no con-elation between serum levels of IgG to bovine insulin with daily intake of dairy products. Bovine insulin cross-reacted with human insulin as judged by ELISA inhibition assay.Conclusion: The emergence of anti-insulin antibodies in Iranian patients with type I DM, which is associated with the duration of breast-feeding is less likely to be due to early exposure of infants with the proteins found in cow’s milk. One speculation could be that the production of antibodies to insulin in type I diabetes may just be a physiologic response (probably to increase the half-life of the circulating insulin). The importance of anti-insulin antibodies in type I diabetes mellitus needs further studies.     

Detection of Epstein-Barr Virus DNA in Plasma and Lymph Node Biopsy Samples of Pediatric and Adult Patients with Hodgkin Lymphoma

Hodgkin lymphoma (HL) is commonly associated with latent Epstein-Barr virus (EBV) infection. The aim of this study is a molecular analysis of the EBV status in both involved lymph node biopsies and plasma samples of patients with HL. Plasma and lymph node biopsy samples obtained from 15 pediatric and 10 adult HL patients were examined for EBV DNA using conventional polymerase chain reaction (PCR). The control group consisted of 30 healthy pediatrics and adults. In addition, immunoglobulin G (IgG) anti-EBV nuclear antigen (EBNA)-1 antibody was determined in sera of patients and controls using enzyme-linked immunosorbent assay (ELISA). IgG Anti EBNA-1 antibody was detected in 21 (84%) and 8 (26%) of patients and controls, respectively (P < .05). EBV DNA was detected in 12 (48%) and 1 (3%) plasma samples of patient and control cases, respectively. Significant difference was observed in plasma DNA detection between patients and controls (P < .05). Comparison of EBV DNA detection in plasma and biopsy samples between children and adult patients was only significant for plasma samples (P = .025). Significant correlation was observed in positive detection of EBV DNA between plasma and biopsy samples of the same individual (P < .001, r = .923). Frequency of EBV DNA in plasma and biopsy samples obtained from mixed-cellularity subgroup was higher than the nodular sclerosis; however, no significant difference was observed between these 2 subgroups. EBV detection in plasma of childhood Hodgkin lymphoma in a population with EBV seroconversion might be of value as a biomarker for EBV-associated Hodgkin lymphoma.     

Advances in Kawasaki disease

Recent studies have increased our understanding of the etiopathogenesis of Kawasaki disease (KD). The inflammatory infiltrate in KD coronary artery aneurysms has been shown to consist of CD8 T lymphocytes, macrophages, and IgA plasma cells, consistent with an immune response to an intracellular pathogen with a mucosal portal of entry. The identification of an oligoclonal IgA response in the vascular wall and the detection of a KD-associated antigen in inflamed KD tissues using a synthetic antibody derived from KD oligoclonal IgA antibodies have provided new approaches to identification of the etiologic agent. Highly effective therapy has evolved for KD, even in the absence of identification of the etiologic agent. The existence of incomplete KD cases remains a significant diagnostic dilemma for the clinician. Conclusion: the development of a diagnostic test, more specific therapy, and ultimate prevention of this potentially fatal illness of childhood are dependent upon continued advances in determining the etiopathogenesis of this fascinating disorder.Abbreviations KD Kawasaki disease - IVIG intravenous immunoglobulin     

抗脂肪阿拉伯酸甘露聚糖抗体检测对儿童肺外结核病诊断价值探讨

目的　探讨抗脂肪阿拉伯酸甘露聚糖抗体 (LAM IgG)对儿童肺外结核病的诊断价值。方法　检测 5 2例肺外结核病患儿、4 2例单纯肺门淋巴结结核和 30例非结核病患儿血清或 (和 )体腔液LAM IgG和结核菌纯蛋白衍化物 (PPD)皮试。结果　PPD试验对诊断儿童结核病的特异性为 83 3% (2 5 /30 ) ,但对儿童肺外结核病和单纯肺门淋巴结结核的敏感性分别为 2 8 8%和 90 5 % (χ2 =35 88,P <0 0 1) ;LAM IgG对诊断儿童结核病的特异性为 96 7% (2 9/30 ) ,但对儿童肺外结核病和单纯肺门淋巴结结核的敏感性分别为 6 9 2 %和 9 5 % (χ2 =33 88,P <0 0 1) ;PPD和LAM IgG对儿童结核病的特异性差异无显著性 (χ2 =2 96 ,P >0 0 5 )。结论　LAM IgG对儿童肺外结核病有较好的诊断价值。     

Mite Antigen in Kawasaki Disease

The relation between house dust mite antigen and Kawasaki disease (KD) wasexamined immunologically in 60 patients with KD.

• 1) In most patients, the serum IgE was significantly raised during the acute phase of the disease and fell gradually during convalescence. 2) Although anti-mite (Dermatophagoides pteronyssinus) specific IgE (RAST) values during the illness were significantly raised in only 15 patients (25%) when expressed as RAST scores, there was a correlation between serum IgE and anti-mite specific IgE (expressed as counts/min) (r=0.56; p<0.01). 3) An intradermal skin test on reactivity to mite antigen gave positive or false-positive in 34 of 60 patients (57%) transiently or persistently during the illness. 4) The serum levels of anti-mite (D.pteronyssinus) specific IgG were estimated by the IgG RAST method. In 15 of 20 patients (75%) RAST values were persistently or transiently high. 5) The presence of mite antigen in circulating immune complexes in the patients was examined by Raji cell assay and the direct fluorescein isothiocyanate labelled anti-mite rabbit gammaglobulin method. In three of eight patients specific fluorescence was seen on the surface of cells. 6) The proliferative responses of lymphocytes to mite ryltigen and phytohaemaglutinin (PHA) were examined in six patients. The response to mite antigen of lymphocytes from the patients was significantly higher than those of age-matched controls (p<0.0.1). 7) More mite (Dermatophagoides spp) were found in house dust collected from the homes of 12 patients than in that of dust from 10 control homes (p<0.0 1).

These results support the hypotheses that mite antigen may invade the body via the upper respiratory tract and act as a respiratory allergen and form circulating immune complexes, resulting in an immune copledx disease such as vasculitis.