Serum IgG Subclasses Research Articles

The immunologic deficiency of Rubinstein-Taybi syndrome

Rationale Rubinstein-Tabyi syndrome is characterized by broad toes and thumbs. It is estimated that approximately 75% of patient with RTS experience respiratory infections. We have found that an immunologic abnormality may be the true cause of their infections. Methods Four patients with Rubinstein-Taybi syndrome and recurrent infections were evaluated for an immunological deficiency. Results JC experienced several episodes of pneumonia, fever, otitis media and sinusitis. Immunologic evaluation showed that JC had low T cells numbers and decreased function to mitogens. Serum immunoglobulins were normal but antibody response to polysaccharide antigens were absent. The patient was started on IVIgG replacement therapy. AR has experienced chronic otitis media. He has had tympanoplasty, mastoidectomy and removal of cholesteatoma. Immunologic evaluation shows an absent IgA and IgG2 subclass deficiency. Absent responses to polysaccharide antigens were noted. Lymphocyte markers were normal. MB experienced frequent otitis media and one episode of pneumonia. The otitis infections were not alleviated by 4 sets of tympanostomy tubes. Infections persisted till the age of 24, his present age. MB had normal T cells for his age. Serum immunoglobulin and IgG subclass levels were normal. Antibody responses to polysaccharide antigens were abnormally low. One other patient is in the process of immunological evaluation but appears to have a similar defective antibody response to polysaccharides. Conclusions We propose that a primarily humoral defect may exist in this population. The humoral defect primarily is one of a lack of antibody response to polysaccharide antigens. Aggressive investigation and management in patients with RTS may enhance the quality of life that these patients.

Pneumococcal antibody responses in elite swimmers.

The ability of elite swimmers to mount an antibody response to the pneumococcal vaccine, Pneumovax 23, was assessed at the end of an intensive 12-week training programme. Antibody titres to six pneumococcal polysaccharide types were measured in 20 elite swimmers (10 male, 10 female) aged 17-23 years and 19 sedentary age- and sex-matched students (eight male, 11 female) aged 18-23 years. Blood samples were tested 14 days apart to assess the magnitude of the antibody response and changes in serum immunoglobulin isotypes and IgG subclasses. There were no significant differences in any of the pneumococcal antibody responses to the Pneumovax between swimmers and controls, and no gender effect, either before or after vaccination. The clinically adequate response to the vaccine was greatest for the pneumococcal serotype 4, which was 97% for the total study population. There were no significant correlations between the magnitude of any of the pneumococcal antibody responses and (i) changes in the scores for the swimmers' international performance; (ii) infection rates in either swimmers or controls; (iii) any psychological variables, assessed by the Profile of Mood States (POMS) questionnaire for either swimmers or controls. Swimmers had significantly lower concentrations of serum IgG2 (P = 0.04) and IgG3 (P = 0.002) before pneumococcal vaccination. The swimmers had an increase in all immunoglobulin isotypes and IgG subclasses post-vaccination, suggesting a polyclonal response to the vaccine that was not observed in control subjects. The magnitude of the subclass responses after vaccination was significantly greater in swimmers compared with controls for IgG1 (P = 0.04), IgG3 (P = 0.04) and IgG4 (P = 0.01). The data indicated that elite swimmers undertaking an intensive training programme were capable of mounting an antibody response to pneumococcal antigens equivalent to that of age- and sex-matched sedentary control subjects, despite the swimmers having lower prevaccination levels of serum immunoglobulins.

Immune deficiencies following cancer treatment in children.

The aim of this study was to determine serum immunoglobulins, IgG subclasses, lymphocyte subsets, and serum protective antitoxin levels of tetanus and diphtheria, and to investigate specific antibody response to tetanus and diphtheria vaccines in children with cancer who have been treated for leukemias and solid tumors. Forty patients with different types of childhood malignancies were enrolled in this study and their lymphocyte subsets, serum Ig A, M, G and IgG subclass concentrations were determined at completion of chemotherapy and 6 months later. We measured serum diphtheria (D) and tetanus (T) antitoxin levels and investigated specific antibody responses against DT vaccines at 6 months. Only the leukemic children had low CD19+ cells at completion of chemotherapy and 6 months later. The patients with solid tumors had reduced CD4+ cells, but increased natural killer cells at completion of chemotherapy. Serum IgA and IgM levels were decreased in leukemic patients after chemotherapy. There were no IgG subclass deficiency. Forty-two per cent of the patients did not have protective serum T antitoxins. All patients produced high levels of DT antibodies by vaccination. Immune system changes recover by 6 months after cancer therapy in children. Children with solid tumors, as well as leukemias, should be followed-up in terms of immune deficiencies. A repeat dose of tetanus toxoid should be recommended at 6 months.

Immunoglobulin subclasses and HLA alleles in immunoglobulin A deficiency.

The term "IgA Deficiency (IgAD)" should be reserved for the individuals who do not have detectable disorders known to be associated with low IgA levels. IgG subclass deficiency or a lack of the IgG2 subclass that is specific against polysaccharide antigens, can be seen in many cases. Forty-five patients (27 males and 18 females; mean age 8.6 years, range 6.3 to 12.8 years) with IgA deficiency who had been admitted to the Department of Pediatric Immunology in Uludag University School of Medicine, Turkey, were included in this study. Serum immunoglobulin (Ig) class and IgG subclass levels, and HLA haplotypes were prospectively determined in patients and healthy controls. Of the 45 patients with IgAD, 1 was found to have a low level of IgG in the serum. Serum Ig levels were also examined in the families of 22 patients. Five patients had low-normal levels of IgM, whilst one had low levels of IgA and IgG. The levels of IgG subclasses were assessed in 23 patients. One patient had a low level of IgG1; 2 had low levels of both IgG2 and IgG3, and 11 had low levels of IgG3. IgG subclass concentrations were found to be normal in control groups. HLA alleles were tested in 25 patients. An increased prevelence of HLA-A1, -B8, -B14, -DR1, -DR3, and -DR7 were previously observed in patients with IgA deficiency. In this study, HLA-A1 allel was found in 3 patients (12%), HLA-B14 in 3 patients (12%), HLA-DR1 in 10 patients (40%), HLA-DR7 in 4 patients (16%) and HLA-DR3 in 1 patient (4%). HLA-B8 allel was not found in any patient. Twenty-five children with normal IgA levels have chosen as a control group. They had HLA-DR1 (36%), HLA-DR7 (16%), HLA-B8 (8%), HLA-DR3 (16%). HLA-A1 was not found in any member of our control group. No statistically significant difference in HLA susceptibility alleles was found between patients and healthy controls. Our data suggest that there may be heterogenous HLA distribution patterns in IgA deficiency, or that HLA allel-associated tendency to IgA deficiency may be polygenic.

Defensin-induced adaptive immunity in mice and its potential in preventing periodontal disease.

The severity of periodontal disease is dependent on a combination of host, microbial agent and environmental factors. One strong correlate related to periodontal disease pathogenesis is the immune status of the host. Here we show that human neutrophil peptide (HNP) defensins or human beta-defensins (HBD), co-administered intranasally with the antigen ovalbumin (OVA), induce unique immune responses that if used with microbial antigens may have the potential to hinder the pathogenesis of periodontal disease. C57BL/6 mice were immunized intranasally with phosphate buffered saline (PBS) containing 1 micro g HNP-1, HNP-2, HBD1 or HBD2 with and without 50 microg OVA. At 21 days, isotypes and subclasses of OVA-specific antibodies were determined in saliva, serum, nasal wash, bronchoalveolar lavage fluid, and fecal extracts. OVA-stimulated splenic lymphoid cell cultures from immunized mice were assessed for interferon (IFN)-gamma, Interleukin (IL)-4 and IL-10. In comparison with mice immunized with only OVA, HNP-1 and HBD2 induced significantly higher (P < 0.05) OVA-specific serum IgG, lower, but not significant, serum IgM and significantly lower (P < 0.05) IFN-gamma. In contrast, HNP-2 induced low OVA-specific serum IgG and higher, but not significant, serum IgM. HBD1 induced significantly higher (P < 0.05) OVA-specific serum IgG, higher, but not significant, serum IgM, and significantly higher (P < 0.05) IL-10. The elevated serum IgG subclasses contained IgG1 and IgG2b.

Immunoglobulins and immunoglobulin subclasses in the elderly.

Published data imply that adult concentrations are achieved for all Ig isotypes and plateau by 15-18 years of age. Recent data, however, suggest that these results are not applicable in the elderly. There are no equivalent data for IgG subclasses. We present reference range data for an elderly UK patient population, for IgG, IgA, IgM and IgG subclasses. Serum immunoglobulins were reviewed on samples from 1146 patients > 60 years of age and 925 patients aged 18-60 years. Serum IgG subclasses were reviewed on samples from 498 patients >60 years and 484 patients aged 18-60 years. All Igs and subclasses were measured by nephelometry. Reference ranges were derived by probability plotting. Serum median IgG and IgM concentrations are reduced in the elderly (IgG female P < 0.001, IgG male P < 0.03; IgM female P < 0.001, IgM male P < 0.001). Serum IgA concentrations are maintained. Indeed, men showed a slight increase in serum IgA with age (P = 0.03). Few differences dependent on gender were seen. Median IgM was lower in men in the younger age groups (18-60 years P < 0.001; 61-70 years P = 0.017). IgG(2) is reduced in elderly men (P = 0.002) and IgG, reduced in elderly women (P = 0.009). We advocate that centres offering these investigations provide local, method-dependent reference ranges, and suggest an approach as to how this might be achieved.

Increased serum albumin, gamma globulin, immunoglobulin IgG, and IgG2 and IgG4 in autism.

Research on the biological pathophysiology of autism has found some evidence that immune alterations may play a role in the pathophysiology of that illness. As a consequence we expected to find that autism is accompanied by abnormalities in the pattern obtained in serum protein electrophoresis and in the serum immunoglobulin (Ig) and IgG subclass profile. We examined whether subjects with autism showed changes in total serum protein (TSP) and the serum concentrations of albumin, alpha1 globulin, alpha2 globulin, beta globulin and gamma globulins, IgA, IgM and IgG and the IgG subclasses IgG 1, IgG2, IgG3 and IgG4, compared with normal controls. We found significantly increased concentrations of TSP in autistic subjects, which were attributable to increased serum concentrations of albumin and gamma globulin. Serum IgG, IgG2 and IgG4 were also significantly raised. In autism there were significant and positive correlations between social problems and TSP and serum gamma globulin and between withdrawal symptoms and TSP and serum albumin and IgG. The results suggest that autism is characterized by increased TSP, a unique pattern obtained in serum protein electrophoresis, i.e. increased serum albumin and IgG, and by a specific IgG subclass profile, i.e. increased serum IgG2 and IgG4. The increased serum concentrations of IgGs in autism may point towards an underlying autoimmune disorder and/or an enhanced susceptibility to infections resulting in chronic viral infections, whereas the IgG subclass skewing may reflect different cytokine-dependent influences on autoimmune B cells and their products.

Salivary gland delivery of pDNA-cationic lipoplexes elicits systemic immune responses.

To test the ability of two cationic lipoplexes, Vaxfectin and GAP-DLRIE/DOPE, to facilitate transfection and elicit immune responses from plasmid DNAs (pDNAs) after retrograde instillation into salivary glands. Two pDNA expression vectors encoding either the influenza NP protein or human growth hormone (hGH) were complexed with the cationic lipid transfection reagents, GAP-DLRIE/DOPE or Vaxfectin, and delivered to the submandibular glands of rats. Samples from rats receiving the influenza NP protein pDNA and cationic lipoplexes were analyzed for anti-influenza NP-specific IgG1, IgG2a, and IgG2b in serum, and IgA in saliva, by an enzyme- linked immunosorbent assay (ELISA). Cytotoxic T-cell lymphocyte (CTL) assays were also performed. Transgene protein expression (hGH) was determined from extracts of submandibular glands of rats receiving hGH lipoplexes. Serum antibodies (IgG) against the NP protein developed and were highest in all rats vaccinated with GAP-DLRIE/DOPE or Vaxfectin. The major serum IgG subclass stimulated by this route of immunization was IgG2b, followed by IgG2a. CTL assay results showed statistically significantly higher percentage killing in the Vaxfectin group than controls (P < 0.05). No rats developed IgA antibodies to NP protein in saliva. Animals receiving plasmid encoding hGH and either lipoplex expressed significantly higher amounts of hGH compared with those receiving the hGH plasmid and water. Although hGH expression was higher in the animals receiving pDNA/Vaxfectin (approximately 30-fold > pDNA/water), the difference with those receiving pDNA/GAP-DLRIE/DOPE (approximately 10-fold > pDNA/water) was not significant. Retrograde instillation of pDNA complexed with Vaxfectin into the salivary glands can stimulate cytotoxic and humoral responses to the influenza NP protein antigen. Optimization of the conditions required to stimulate humoral and secretory antibody formation may facilitate use of this tissue for specific clinical applications of pDNA immunization.

Heterogeneity of humoral immune abnormalities in children with Nijmegen breakage syndrome: an 8-year follow-up study in a single centre.

During an 8-year period of observation, defects of immune responses were characterized and monitored in 40 of 50 Polish children with Nijmegen breakage syndrome referred to the Children's Memorial Health Institute in Warsaw. The following parameters were determined at diagnosis: (1) concentrations of serum IgM, IgG, IgA; (2) concentrations of IgG subclasses; and (3) lymphocyte subpopulations. In addition, naturally acquired specific antibodies against Streptococcus pneumoniae were determined in 20 patients with a history of recurrent respiratory infections. During follow-up, total serum immunoglobulins and IgG subclasses were monitored systematically in 17 patients who did not receive immunomodulatory therapy. Moreover, anti-HBs antibody response was measured after vaccination of 20 children against HBV. We found that the immune deficiency in NBS is profound, highly variable, with a tendency to progress over time. Systematic monitoring of the humoral response, despite good clinical condition, is essential for early medical intervention.

Humoral immunity and bronchiectasis.

Bronchiectasis is a common complication of primary antibody deficiency but the incidence of antibody deficiency as an underlying cause of bronchiectasis is largely undefined. In this study the humoral immune status of a cohort of bronchiectatic patients was investigated to detect the frequency of significant antibody deficiency and to determine the extent of immunological investigation which is appropriate for routine assessment of bronchiectasis patients. Fifty-six out-patients (with a mean age of 59.6 years) had serum immunoglobulins, IgG subclasses and specific antibodies to capsular polysaccharides of Haemophilus influenzae and Streptococcus pneumoniae measured. Where specific antibody -levels were low, where possible, appropriate immunization with pneumococcal or conjugated Haemophilus polysaccharide vaccines was offered and the responses quantified. Three of 56 patients had low total serum IgG levels. Thirteen of 56 had deficiencies of either a single IgG subclass or combinations of two or more subclasses, with IgG4 being most frequently implicated (9/56). Twenty-nine of 56 had low basal specific polysaccharide antibody levels. Test immunization, where performed, produced satisfactory responses in all cases except one, where a specific defect of responsiveness to pneumococcal polysaccharide was identified. This study indicates that antibody deficiency is an uncommon aetiological/underlying factor in the causation of bronchiectasis beyond the fourth decade and that detailed investigation of humoral immune status as a routine in bronchiectasis patients, at least at this age, is not generally justified.

The transplacental transfer of IgG subclasses: influence of prematurity and low birthweight in the Gambian population.

Having established previously that prematurity in The Gambia is associated with impaired maternofetal transfer of some specific antibodies, we investigated the influence of low birthweight and prematurity on placental transfer of IgG subclasses in 180 Gambian mothers and their newborn babies. A physician-blinded, cross-sectional study of 180 mother-baby pairs was carried out in the labour ward of Bansang Hospital, The Gambia. Paired maternal and cord serum samples were collected from mothers and their newborns. Serum IgG subclass levels were measured by laser nephelometry. Placental transfer of all IgG subclasses was significantly reduced in preterm newborns compared with term newborns (p < 0.01). In low birthweight (LBW) babies, the transfer of IgG1 (p = 0.03) and IgG2 (p < 0.01) subclasses, but not IgG3 and IgG4, was significantly reduced. In preterm neonates with an adequate birthweight and term neonates with a low birthweight, all IgG subclasses were transferred with reduced efficiency, but IgG1 and IgG2 subclasses were transferred with significantly less efficiency than IgG3 and IgG4. These results confirm that prematurity and low birthweight are associated with impaired placental transfer of IgG1 and IgG2 subclasses in this Gambian population. This impairment might explain the susceptibility of these newborns to certain polysaccharide-encapsulated organisms.

IgG and IgG subclasses deficiency in children undergoing continuous ambulatory peritoneal dialysis and its provocative factors.

Low levels of serum IgG or IgG subclasses may be responsible for the defective peritoneal defense and for peritonitis attacks in continuous ambulatory peritoneal dialysis (CAPD) children. Malnutrition, peritoneal loss or frequent peritonitis may lead to IgG or IgG subclasses deficiency. Levels of IgG subclasses were determined in 12 children undergoing CAPD treatment. Radial immunodiffusion technique was used for determination. Patients were aged from 6 to 16 years (mean age 12.3 years) and had been on CAPD for 11-26 months (mean duration 19.4 months). We evaluated whether IgG and IgG subclasses deficiency are related to malnutrition, the peritonitis rate and the duration of CAPD using the SPSS program. Serum total IgG levels were found to be low in eight out of 12 patients. Eight patients showed low levels of IgG1, four patients IgG2, one patient IgG3 and three patients IgG4. Total IgG values were found to be positively correlated to malnutrition status, peritonitis rate and duration of CAPD. The IgG2 values were found to be related to the duration of CAPD. The IgG4 values were found to be correlated to the peritonitis rates. The IgG and IgG subclasses deficiency may develop in children while on CAPD treatment. Periodical determinations of either serum IgG or the subclasses may be useful in the follow-up of these patients.

Glomerular and serum IgG subclasses in diffuse proliferative lupus nephritis, membranous lupus nephritis, and idiopathic membranous nephropathy.

To determine whether a different renal histopathology is associated with the characteristic IgG subclass distribution, and whether a distinct IgG subclass distribution is involved in a unique immunopathological expression, we compared the distributions of glomerular and serum IgG subclasses in diffuse proliferative lupus nephritis (DPLN), membranous LN (MLN), and idiopathic membranous nephropathy (MN). The glomerular IgG subclass distributions in patients with DPLN (n=7), MLN (n=10) or MN (n=16) were assessed by direct immunofluorescence microscopy. Serum levels of each IgG subclass were quantitated by ELISA in DPLN, MLN, and MN patients, and in normal human sera (NHS) (n=14). IgG1, IgG2, IgG3, and, to a lesser degree, IgG4 were similarly present in glomerular deposits in both DPLN and MLN. In contrast, IgG4 was the predominant glomerular IgG subclass in MN. Regarding the serum IgG subclasses, the mean IgG subclass concentrations and the mean proportion of each IgG subclass to the total IgG (%IgG subclass) in DPLN and MLN were not significantly different from those in NHS, except for the increased %IgG1 in MLN. In MN, the mean %IgG4 was selectively increased (p<0.01 vs NHS) in association with a slightly elevated IgG4 concentration; however, the mean concentrations of other IgG subclasses were significantly decreased (p<0.01 vs NHS), and the %IgG subclasses were not significantly different from those in NHS. The results indicate that the IgG subclass distribution is not associated with the different renal histopathologies of DPLN and MLN. This study also shows the selective significance of IgG4 in MN, but not in MLN, another form of membranous glomerulopathy.

Serum IgG subclasses levels in paediatric patients with pneumonia.

To determine the IgG subclass levels of patients admitted to Harare Central Hospital paediatric wards with pneumonia. A cross sectional study. Harare Central Hospital, Departments of Immunology and Paediatrics, University of Zimbabwe; Department of Paediatric Immunology, University of Utrecht, The Netherlands. 56 paediatric patients. IgG subclass profiles of children with pneumonia. Of the 56 children tested, 40 (71%) had antibodies to human immunodeficiency virus (HIV). The levels of IgG1 and IgG3 subclasses were significantly higher in HIV antibody positive children (p < 0.001, p < 0.01 respectively) than in those without detectable HIV antibodies in their sera. There was no significant relationship between IgG subclass levels and the presence of HIV p24 antigen. Furthermore, age and gender also had no significant influence on the levels of IgG subclasses in this population. High levels of IgG1 and IgG3, but not IgG2 and IgG4, occur frequently in children with pneumonia and are associated with the presence of HIV antibodies.

Immunization with recombinant Streptococcus gordonii expressing tetanus toxin fragment C confers protection from lethal challenge in mice

Tetanus toxin fragment C (TTFC) was expressed on the surface of the vaccine vector Streptococcus gordonii, a Gram-positive commensal bacterium of the human oral cavity. The immunogenicity of recombinant S. gordonii expressing TTFC was assayed in mice immunized by the parenteral and mucosal routes. High serum TTFC-specific IgG responses were induced in both BALB/c and C57BL/6 mice immunized subcutaneously. A total of 82% of vaccinated BALB/c mice were protected from the lethal challenge with 50 LD 50 of tetanus toxin (TT) and a direct correlation between the serum TTFC-specific IgG concentration and survival time of unprotected animals was observed. Intranasal immunization of BALB/c mice was also effective in inducing TTFC-specific serum IgG and local IgA in lung washes. Furthermore, 38% of animals immunized intranasally were protected from the lethal challenge with 10 LD 50 of TT while all control animals died within 24 h. Analysis of the serum IgG subclasses showed that the IgG1 subclass was predominant after parenteral immunization in BALB/c mice (IgG1/IgG2a ratio ≅6) while following mucosal immunization a mixed IgG1 and IgG2a pattern (IgG1/IgG2a ratio ≅1) was observed. These data show that TTFC expressed on the surface of S. gordonii is immunogenic by the subcutaneous and mucosal routes and the immune response induced is capable of conferring protection from the lethal challenge with TT.

Serum immunoglobulins and immunoglobulin G subclasses with recurrent wheezing.

In this study serum immunoglobulins (Ig) and IgG subclasses were measured in 42 patients (ranging 9 month-6 year) with recurrent wheezing and in 37 healthy children determined the relationship between serum Igs and recurrent wheezing. Patients were divided into two groups according to the age [9 month-2 year (n: 15), and 2-6 year (n: 27)]. In the patients placed in 9-24 month age group, serum IgG4 level was found to be lower than controls (p < 0.05). But there was not a significant difference in mean serum concentrations of total IgG, IgA, IgM, IgE, IgG1, IgG2 and IgG3 subclasses between the groups (P > 0.05). In the 25 month-6 year age group the mean IgE level was increased compared to the control while IgG3 and IgG4 levels were decreased (p < 0.05). On the other hand, in the 9-24 month age group there was no significant difference between the patients and controls for IgG subclasses deficiency (P > 0.05). However, significant difference in IgG subclasses deficiency was present between the patients and controls in the 25 month-6 year group (P < 0.001). In conclusion, our findings suggest that wheezing in childhood may be associated with low IgG3 and/or IgG4, and in older children high IgE level may be a part of pathogenetic mechanism in patients with recurrent wheezing.

COUGH, FATIGUE AND BRONCHOPULMONARY DISEASE IN TWO IMMUNOCOMPETENT CHILDREN

Case 1. A previously healthy 5-year-old boy presented with frequent coughing, fatigue, fever (up to 40°C) and a 2-kg weight loss. His white blood cell count (WBC) was 27 000/mm3 and C-reactive protein was 130 mg/dl. A clinical diagnosis of pneumonia was made, and he was treated with a 10-day course of oral erythromycin. Failing to improve he was then treated with cefaclor. A standard Mantoux skin test was positive with 11 mm of induration with blister formation. A Mantoux test 1 year before had shown no induration. He had no known exposure to adults with tuberculosis and had never received the Calmette-Guérin bacillus vaccine. The patient was admitted for further evaluation and treatment. On admission the child was febrile (38°C) and ill-appearing. Physical examination revealed mild intercostal retractions and bilateral expiratory wheezes. The remainder of the examination was normal. An initial chest radiograph demonstrated a right hilar mass with right upper and middle lobe infiltrates (Fig. 1). Fig. 1: Chest radiograph of Patient 1 on admission. Posterior-anterior view.Initial laboratory studies revealed a WBC of 22 200/mm3 with 55% neutrophils, 33% lymphocytes, 7% monocytes and 5% eosinophils. Hemoglobin and platelets were normal. Erythrocyte sedimentation rate was 90 mm/h. Acid-fast stains of three separate samples of gastric fluid, sputum and urine collected on different days were negative. PCR for Mycobacterium tuberculosis and nontuberculous mycobacteria was negative for the same samples. HIV serology was negative. Values were normal for serum quantitative immunoglobulins and IgG subclasses. Laboratory tests for granulocyte function as well as the function of lymphocytes by mitogen stimulation were all normal. Two weeks after admission a repeat chest radiograph revealed progressive enlargement of the right hilum with a mild mediastinal shift toward the right side. At the same time bronchoscopy revealed a total occlusion of the bronchus intermedius because of perforation of a lymph node. Necrotic lymph node material had histologic evidence of epithelioid cell granulomata. Microscopic examination showed no acid-fast bacilli. Bronchial secretion and lymph node material were cultured. Because of tuberculin conversion, abnormal chest radiographs and bronchoscopic findings, the patient was started on antituberculous chemotherapy with isoniazid, rifampin and pyrazinamide. Despite therapy there was no improvement clinically or according to serial chest radiographs during 4 weeks. Case 2. A 3.5-year-old boy suffered from a persistent cough and fatigue for 6 weeks. A standard Mantoux skin test showed a positive reaction of 10 mm of induration. The boy had not received Calmette-Guérin bacillus vaccine and had no known exposure to adults with tuberculosis. On physical examination there was no fever and no respiratory distress. Breath sounds in the right upper lobe were reduced along with percussive dullness in this area. The remainder of the examination was normal. Laboratory studies showed a WBC of 20 300/mm3 with 62% segmented neutrophils, 27% lymphocytes, 11% monocytes and normal hemoglobin and platelets. The patient had a normal erythrocyte sedimentation rate and C-reactive protein. HIV serology was negative. Laboratory studies for granulocyte and lymphocyte function were normal. Serum values for quantitative immunoglobulins and IgG subclasses were normal. Radiographic examination revealed an enlargement of the right hilum and a progression of poststenotic infiltration of the right upper lobe with atelectasis. Mycobacterium avium-PPD (RS 10-Sensitin; Statens Seruminstitut, Copenhagen, Denmark) administered intradermally showed 12 mm of induration. Three samples of sputum, gastric fluid and urine were collected and sent for additional studies. Acid-fast bacillus stains were negative as was PCR analysis for M.tuberculosis and nontuberculous mycobacteria. Bronchoscopy showed a stenosis of the right upper lobe bronchus caused by to perforation of a lymph node. Necrotic lymph node material on histologic analysis showed epithelioid cell granulomata. Combined antituberculous chemotherapy was started with isoniazid, rifampin and pyrazinamide. Despite therapy there was no improvement during the next 4 weeks. In both patients results of cultures revealed the diagnosis.

Immunoglobulin isotypes in sera and nasal mucosal secretions and their neonatal transfer and distribution in horses.

To determine concentrations of IgA and IgG subclasses in serum, colostrum, milk, and nasal wash samples of adult horses and foals. Seven 2-year-old Welsh ponies, 27 adult mixed-breed horses, and 5 Quarter Horse mares and their foals. Serum was obtained from ponies and adult horses. Colostrum and milk were obtained from mares and serum and nasal wash samples from their foals immediately after parturition and on days 1, 7, 14, 28, 42, and 63. Nasal wash samples were also obtained from 23 adult horses. Concentrations of immunoglobulins were determined by use of inhibition ELISA. To determine transfer of maternal isotypes to foals, concentrations in colostrum and milk were compared with those in foal serum. Serum half-lives of isotypes in foals were also determined. IgGb was the most abundant isotype in serum and colostrum from adult horses, whereas IgA was the predominant isotype in milk. The major isotype in nasal secretions of adult horses and foals > or = 28 days old was IgA, but IgGa and IgGb were the major isotypes in nasal secretions of foals < or = 14 days old. Serum half lives of IgGa, IgGb, IgG(T), and IgA in foals were 176, 32, 21, and 3.4 days, respectively. The early immunoglobulin repertoire of neonatal foals comprised IgGa, IgG(T), and IgA; endogenous synthesis of IgGb could not be detected until 63 days after birth. The restricted repertoire of immunoglobulins in foals may influence humoral immune responses to vaccination.

Prospective analysis suggests susceptibility genes for deficiencies of IgA and several other immunoglobulins on the [HLA-B8, SC01, DR3] conserved extended haplotype.

The extended major histocompatibility complex (MHC) haplotype [HLA-B8, SC01, DR3] is increased in frequency among patients with immunoglobulin (Ig)A deficiency and common variable immunodeficiency. Because the genomic region from HLA-B to HLA-DR/DQ is virtually the same on all instances of the haplotype in the general population, we reasoned that all independent instances of [HLA-B8, SC01, DR3] carry MHC susceptibility genes for these disorders. To define immunoglobulin deficiencies determined by genes on this haplotype and their mode of expression and penetrance, serum immunoglobulin class and IgG subclass concentrations were determined prospectively in homozygotes and heterozygotes of this haplotype and in Caucasian controls. Prevalence of individual immunoglobulin deficiencies in persons with [HLA-B8, SC01, DR3] ranged from 13% to 37%, significantly higher than rates in non-carriers or general controls. We found significantly increased frequencies of IgA and IgG4 deficiency only in homozygotes (13.3% and 30%, respectively) compared with heterozygotes (1.7% and 3.4%) or non-carriers (1.6% each), suggesting recessive expression. In contrast, IgD and IgG3 deficiencies were significantly more common in both homozygotes (36.7% and 30%) and heterozygotes (20.3% and 17.5%) compared with controls (4.9% and 3.4%), suggesting dominant inheritance. These results indicate multiple distinct susceptibility genes, some recessive and others dominant, for deficiency of IgA, IgD, IgG3 or IgG4 (but not for IgE, IgG1, IgG2 or IgM) on [HLA-B8, SC01, DR3]. These observations may also help to explain the observed associations of [HLA-B8, SC01, DR3] with both IgA deficiency and common variable immunodeficiency and the common occurrence of IgG subclass deficiencies in some patients with IgA deficiency.

Immunoglobin subclasses and determination of specific antibodies. What role in the study of children with recurrent pneumonias?

Recurrent pyogenic infections, including pneumonia, are known to occur in children with a defective immune system. Until recently, diagnosis was made by measuring major immunoglobulin isotypes and IgG subclasses. Recent reports show that in some cases all these measurements are normal, but that there is a defect in the production of specific protein or polysaccharide antibodies. To study immune function in children with recurrent pneumonia to determine the most appropriate immunologic studies for the evaluation of recurrent infections in children. Forty-three children (ages 2 to 12 years; mean 5.3 years, 29 male) who were referred to our pulmonology clinic because of recurrent lower respiratory tract infections. Major causes of recurrent infections were excluded by clinical, radiological or laboratory studies. Immunologic studies included serum immunoglobulins, IgG subclasses, IgA subclasses, isohemagglutinins and antibody responsiveness to vaccination with tetanus, rubella, H. influenza b conjugate and pneumococcal polysaccharide. The majority of children had normal or elevated serum immunoglobulin and subclass levels. Three patients had low levels of IgG2 and IgA, alone or simultaneously. Eleven patients failed to respond to Hib or rubella vaccination and one failed to respond to pneumococcal immunisation. Our preliminary results seem to indicate that a high proportion of children with recurrent pneumonia have a demonstrable immunologic abnormality. There is no direct relationship between low levels of IgG subclass and the child's capacity to form antibodies to several antigens. Defects in antibody production are very specific and an extended panel is necessary. Examination of the antibody-forming capacity seems important in the initial evaluation of children with recurrent pneumonia.