Hypoimmunoglobulinemia and protein C deficiency in a girl with Jacobsen syndrome: a case report

Jacobsen syndrome is a rare contiguous gene syndrome caused by partial deletion of the long arm of chromosome 11. The typical clinical manifestations include physical growth retardation, mental retardation,facial dysmorphisms, congenital heart disease, thrombocytopenia, or pancytopenia. A Thai-Australian girl was born with multiple abnormalities. Typical features and her karyotype, 46, XX, del(ll) (q23-qter), confirmed Jacobson syndrome. She had many uncommon findings including upslanting palpebral fissures, tortuousity of retinal vessels and hypogammaglobulinemia. In addition, this case also presented with protein C deficiency, which has not been reported previously in Jacobsen syndrome. The patient was treated with phototherapy, intravenous antibiotic injection, and platelet transfusion in neonatal period. Cranioplasty was performed for prevention of the increased intracranial pressure at three months of age. Surgical correction for strabismus was in the treatment plan.

[IgE deficiency: a forgotten disease?]

BACKGROUND

Selective IgE deficiency is a profound deficiency (< 5 UI/mL) or absence of serum IgE levels without other immunologic abnormalities. It is usually asymptomatic, but may be associated with recurrent respiratory infections, chronic fatigue, and musculoskeletal complaints.

OBJECTIVE

To describe the evolution and treatment in patients with selective IgE deficiency.

PATIENTS AND METHOD

In selective IgE's deficiency patients identification note, atopy history, concurrent diseases, clinic of allergic diseases, Prick test and prior response to treatment were analyzed.

RESULTS

Eleven patients were included, five women and six men within 16 months to 10 years old. The patients had serum IgE levels < 5 UI with other immunoglobulins and sub-classes in normal levels; except a patient with concomitant IgA and IgE deficiency. The treatment administered was since prophylactic antibiotic to intravenous gammaglobulin.

DISCUSSION

We established the diagnosis of selective IgE deficiency in patient with serum IgE levels < 5 UI/mL associated with recurrent respiratory infections.

CONCLUSIONS

We need more clinic studies to document with precision the selective IgE deficiency.

Subcutaneous immunoglobulin replacement therapy for primary antibody deficiency: advancements into the 21st century

OBJECTIVES

To provide a review of the world literature and discuss the clinical role of subcutaneous immunoglobulin (SCIG) therapy for primary antibody deficiency.

DATA SOURCES

English-language publications on SCIG therapy were identified through MEDLINE and through the reference list of the initially identified publications.

STUDY SELECTION

Articles pertaining to SCIG for the treatment of immunodeficiency, particularly primary antibody deficiency, were selected.

RESULTS

SCIG therapy has been shown to be effective and safe for the treatment of primary immunodeficiency. The risk of systemic reactions during infusion is generally reported to be less than 1%. Many patients prefer SCIG over conventional intravenous immunoglobulin therapy because of increased convenience and independence associated with SCIG therapy. Publications show SCIG therapy to be advantageous in selected patient populations, such as children, pregnant women, and patients with poor intravenous access.

CONCLUSION

SCIG therapy has been widely used in some European countries for a number of years, but a Food and Drug Administration-approved product was only recently introduced into the United States in 2006. SCIG therapy offers unique advantages that are applicable to many patients receiving immunoglobulin therapy for primary immunodeficiency.

Immunologic reconstitution following bone marrow transplantation for X-linked hyper IgM syndrome

X-linked hyper IgM syndrome (XHIM), caused by mutations of the CD40 ligand (CD40L) gene, is characterized by recurrent bacterial and opportunistic infections, an increased incidence of autoimmunity and malignancies, and immunodeficiency due to abnormal T/B cell interaction. Because of poor long-term prognosis, bone marrow transplantation (BMT) has been proposed as an alternative treatment. An 8-month-old boy with XHIM and a splice site mutation of CD40L underwent BMT using a fully matched sibling donor. Markers of engraftment and immunologic reconstitution were measured serially. After BMT, activated T cells expressed functional CD40L, and genomic DNA obtained from circulating white cells contained predominantly wild-type CD40L sequences. Serum immunoglobulin levels including IgE and antibody responses to recall antigens normalized, and immunization with the T-cell-dependent neoantigen, bacteriophage &phi;X174, demonstrated amplification of the response and isotope switching. BMT provides a permanent cure for XHIM if a fully matched sibling donor is available and the procedure is performed before complications have occurred.

Follow-up of pediatric patients with recurrent infection and mild serologic immune abnormalities

BACKGROUND

Children with recurrent infections significant enough to warrant referral to an immunologist frequently have mild abnormalities of the humoral immune system. Parents of these children are generally reassured that their child will outgrow the clinical problems that prompted their referral.

OBJECTIVE

This is a retrospective study with the objective being to evaluate changes in immune measurements and clinical status of children with recurrent infections followed in an immunology clinic.

METHODS

Forty-two patients (mean age 60 months) previously evaluated for recurrent infections were re-evaluated after at least 12 months (mean 37 months). Initial evaluation studies included quantitative immunoglobulins in all patients and IgG subclass determinations and pre- and postvaccination pneumococcal polysaccharide antibody titers in a subpopulation of patients.

RESULTS

Patients were assigned to one of two categories: those with initial laboratory abnormalities (27 patients) and those with normal initial studies (15 patients). Among the patients with initial abnormalities, partial IgA deficiency was most commonly seen (20/27). It persisted in 15. Only 6/27 patients had studies that were completely normal on follow-up. Among patients with no initial abnormality, 9/15 developed a partial deficiency of at least one immunoglobulin isotype or IgG subclass. Eighty-six percent of the patients were clinically improved at the time of their last follow-up visit regardless of their laboratory values.

CONCLUSIONS

A high proportion of children with recurrent infection have persistent, partial immunoglobulin deficiencies lasting in some cases for years. Despite this finding almost all patients demonstrate clinical improvement with time.

HCV infection in a patient with hyper IgM syndrome

The association between an acquired form of hyper-IgM syndrome and a chronic hepatitis C virus (HCV) infection in a 71-year-old female patient is described. Both diseases were diagnosed at the age of 58 years. She was started on intramuscular and then intravenous immunoglobulin replacement therapy. HCV RNA was detected in 1992. The patient remained in well-balanced clinical condition until 1994, when total and specific anti-HCV IgM levels increased and the patient developed an IgM kappa monoclonal gammopathy. Adherent cells and B cells were HCV RNA positive, while T cells were HCV RNA negative. Anti-IgM reactivity was specifically directed to the core antigen of the HCV. The patient we describe showed a picture of a late-onset form of hypogammaglobulinemia with a progressive increase in IgM antibodies, possibly due to the concomitant HCV infection. It is possible that the immunodeficiency might also result from the HCV infection, with formation of specific antibodies belonging to the IgM class, and that the worsening of the clinical condition may be directly related to the persistent viral infection.

[Administration of intravenous immunoglobulins in adult patients with hematologic diseases]

Abnormalities in serum immunoglobulin levels or in antibody production may develop as a result of many different diseases. Antibody deficiency may occur in previously normal persons with haematologic malignancies or who received immunosuppressive agents in treatment of cancer or in anticipation of bone marrow transplantation. Effective regimens may develop in primary immunodeficiencies and secondary immunodeficiencies as well as in idiopathic thrombocytopenic purpura. Some reports and information about the other haematological indications were published in medical literature. However, the consensus conference on IVIG at the National Institutes of Health (Bethesda--May 21, 1990) recommended treatment with IVIG in haematology only for CLL, ITP and after bone marrow transplantation, as a prevention for GVHD. The adverse effects of IVIG therapy are minimal, but they exist. The other important subject is the cost of widespread use of IVIG; therefore the indications must be carefully concerned and documented before therapy is started.

Effects of intravenous immunoglobulin on clinical and immunological findings of patients with humoral immunodeficiency diseases

We evaluated nine patients with humoral immunodeficiency (6 immunodeficiency with hyper-IgM, 2 X-linked agammaglobulinemia, 1 common variable immunodeficiency) who were being treated with intravenous immunoglobulins (IVIG). After the use of the IVIG regimen in a dose of 250-300 mg/kg/4 weeks for one year, the severity and frequency of infections, even in patients with chronic lung disease, decreased significantly. An improvement in pulmonary function tests was observed in four patients who had airway obstruction prior to IVIG therapy. Side effects such as chills and fever were observed in 21 of 91 infusions, particularly in the early months of therapy. Preinfusion administration of aspirin and diphenhydramine prevented these side effects. The inversion of the CD4+/CD8+ ratio was detected in most patients during both intramuscular gammaglobulins (IMIG) and IVIG therapy.

Effects of serial plasmapheresis on serum IgA levels in IgA-deficient blood donors with IgA-suppressor T cells

Seventeen IgA-deficient blood donors, without antibodies to IgA, underwent plasmapheresis four to eight consecutive times at intervals of 8 weeks or less to provide fresh-frozen plasma for patients with anti-IgA. Blood samples, drawn for analysis no more than 1 hour before plasmapheresis and again at the conclusion of each procedure, were analyzed for lymphocyte subpopulations and serum IgA levels. Five lymphocyte subpopulations, including natural killer cells, the suppressor-inducer CD4 subset, the suppressor-precursor CD8 subset, non-major histocompatibility complex (MHC)-restricted cytotoxic T cells, and CD5+ B cells, were all decreased significantly after plasmapheresis (p less than 0.05). In a subgroup of IgA-deficient donors with excessive IgA-suppressor T-cell activity, serum IgA increased to levels exceeding 0.05 g per L following the fourth consecutive plasmapheresis procedure. Serum IgA levels did not similarly increase in IgA-deficient donors without excessive IgA-suppressor T-cell activity or in controls without IgA deficiency. Our study shows the potential, in a subpopulation of IgA-deficient donors who undergo frequent plasmapheresis, for a transient increase in serum IgA to a level no longer considered IgA deficient.

[Effect of intraperitoneal administration of sandoglobulin on peritoneal fluid IgG level in patients treated by standard peritoneal dialysis (SPD)]

In 6 patients (PTS) treated with SPD for 369 patient weeks (ptw) we evaluated the influence of three intraperitoneal SI on the IgG concentration in the PE. The concentration of IgG was checked before, on 1-st, 3-rd day 2-nd and 3-rd week after SI. In the course of the following 229 ptw, we observed three episodes of peritonitis (PN) in two pts, while in the control period of 140 ptw no PN occurred. The concentrations in PE of opsonins (IgG, C3 complement, fibronectin) at the start of SPD shoved enormous individual differences and did not correlate with occurrence of PN in the follow-up. Intraperitoneal SI caused significant increase of IgG in PE, but only to the third day after infusion. Our preliminary results do not confirm the protective effect of intraperitoneal SI on occurrence of PN in SPD patients.

[Therapeutic approach in peripheral neuropathies]

On the whole, the treatment of peripheral neuropathies is disappointing, even when a cause has been identified, because nerve lesions, and particularly axonal diseases, are frequently severe, and the mechanisms or peripheral nerve fibre repair is very slow. However, during the last few years important advances have been made in the treatment of acute and chronic acute inflammatory demyelinating polyneuropathies, most probably of dysimmune origin, with plasma exchanges and, more recently, intravenous human plasma immunoglobulins. Therapeutic trials are in progress in neuropathies associated with monoclonal gammopathies, notably IgM. In diabetic neuropathy numerous studies are going on, in particular with aldolase reductase inhibitors and with gangliosides.

Clinical efficacy of intravenous immunoglobulin in patients with severe inflammatory chest disease and IgG3 subclass deficiency

To investigate the efficacy of i.v. IgG treatment in pediatric patients with inflammatory lung disease, a prospective, controlled clinical trial was carried out over a 2-year study period. Patients were enrolled on the basis of severe clinical symptomatology. After 1 year of conventional treatment, the patients received 400 mg/kg per month of an i.v. IgG product containing only trace amounts of IgG3 in addition to their regular treatment throughout the second year. Significant clinical improvement, as documented by duration of hospital stay (first year 27.8 days, second year 4.9 days), use of antibiotics (132.8 versus 30.9 days) and use of steroids (21.4 versus 0.7 days) could be observed. Data obtained on a subgroup of patients with IgG3 deficiency were analysed separately. These results indicate that patients with severe chest disease who have IgG3 deficiency will also benefit from i.v. IgG treatment. The mode of action cannot be attributed to replacement of the respective isotypes, but is probably due to the effect of i.v. IgG in preventing repeated viral infections.

Changes in serum immunoglobulin patterns in adults with common variable immunodeficiency

Striking variations of serum immunoglobulin class and IgG subclass levels were observed in five patients with common variable immunodeficiency. They occurred mainly in untreated patients or, in those patients who received substitutive therapy, could not be merely due to replacement. They result in major changes in the immunoglobulin deficiency patterns, such as a shift from profound hypoimmunoglobulinaemia to IgA/IgG2/IgG4 deficiency or to isolated IgG2 deficiency. These findings have practical implications for the diagnosis and management of patients with primary humoral immunodeficiency.

[Primary immune deficiencies of B-lymphocytes]

Primary B-cell immunodeficiency is relatively frequent and may result in recurrent bacterial infections involving notably the respiratory tract, and in chronic severe enteroviral infections in patients with agammaglobulinaemia. Selective IgG2 isotype deficiency results in pneumococcal, Haemophilus influenzae and pseudomonal infections, since it is associated with defective production of antibodies that are specifically directed against bacterial capsular polysaccharides. Progress has recently been achieved in the determination of genetic and molecular bases of some of these immunodeficiencies. In X-linked agammaglobulinaemia, the abnormal gene has been located on the long arm of the X chromosome (Xq22-23); the intrinsic B-cell abnormality blocks differentiation at the pre-B stage, before the genes coding for light chain immunoglobulins are rearranged. There is now a strong suspicion that IgA deficiency, hypoglobulinaemia with variable expression and some selective IgG isotype deficiencies are three ways of expressing one single abnormality a genetic factor of which is located in the class III region of the HLA complex and perhaps also associated with HLA class II DQ. Treatment of deficient IgG production with intravenous immunoglobulin has thoroughly altered the prognosis of these diseases. Complete IgA deficiency carries a risk of accident by production of anti-IgA antibodies, which means that patients with isolated IgA deficiency should not be treated, that these antibodies should systematically be looked for in patients with IgA deficiency associated with partial deficiency of other immunoglobulins, and that these patients should be treated with IgA-free immunoglobulin preparations.

Selective IgG subclass deficiency: quantification and clinical relevance

Each of the four human IgG subclasses exhibits a unique profile of effector functions relevant to the clearance and elimination of infecting microorganisms. The quantitative response within each IgG subclass varies with the nature of the antigen, its route of entry and, presumably, the form in which it is presented to the immune system. This results in antibody responses to certain antigens being predominantly or exclusively of a single IgG subclass. An inability to produce antibody of the optimally protective isotype can result in a selective immunodeficiency state. This is particularly apparent for responses to certain bacterial carbohydrate antigens that are normally of IgG2 isotype. A failure to produce the appropriate specific antibody response may result in recurrent upper and/or lower respiratory tract infection. Careful patient investigation can identify such deficiencies and suggest appropriate clinical management. In this review we outline the biology and clinical relevance of the IgG subclasses and summarize current rational treatment approaches.

Variable expression of IgG2 deficiency

Sustained and significant reversal of antibody deficiencies is uncommon, although it has been noted in some cases during childhood and after viral infections. We report a case of reversal of IgG2 deficiency after splenectomy. A 46-year-old man who suffered recurrent sinusitis despite antibiotic therapy was noted to have IgG2 deficiency and cutaneous anergy. Replacement therapy with intravenous immunoglobulin ameliorated his symptoms. After 13 months of therapy, the patient had a diagnostic laparotomy and splenectomy because of portal hypertension, hypersplenism, and consideration of underlying malignancy. No evidence of malignancy or infection, including human immunodeficiency virus, active cytomegalovirus, or Epstein-Barr virus infection, was found. After splenectomy, the patient's serum IgG2 level normalized without replacement therapy. Subsequently, it fell, then normalized once more, and remains normal. The patient also demonstrated positive reactions to delayed hypersensitivity testing after splenectomy, but, subsequently, became anergic and remains anergic at the present time. Since the splenectomy he has remained clinically well without antibiotics or immunoglobulin replacement. In vitro analysis of his lymphocyte function demonstrated impaired T cell proliferation as well as an intrinsic B cell differentiation defect. This case demonstrates the potentially dynamic nature of IgG subclass deficiencies.

[Hypogammaglobulinemia G and A with hypergammaglobulinemia M. Apropos of 12 cases]

Hyper IgM with low IgG and IgA is a rare humoral immunodeficiency. We presently report 12 new observations which have been clinically and immunologically studied. On one occasion the syndrome was found to be associated with congenital rubella. Since 10/12 children were male, X-linked inheritance is suggested which has been confirmed in 2 cases. In most cases (9/12), the first infections occurred within the first year of life. The syndrome is causing upper and lower respiratory tract infections due to bacteria, as well as gut infections. Lymphoid organ hyperplasia has been noted in 11/12 patients. Polyclonal hyper IgM serum contrasts with low or absent IgG, IgA and IgE. In some instances, some IgM antibody response was detected. A dysfunction of cellular immunity was not detected. Autoimmunity was detected in 3 patients. Finally, transient neutropenia occurred in 50% of the patients. Intravenous immunoglobulin G substitution treatment resulted in a significant reduction in the occurrence of infections as well as in normalization of growth rate. Immunoglobulin infusion also frequently induced correction of hyper IgM and neutropenia.

[Intravenous immunoglobulin in the treatment of malignant epilepsy in children]

15 children with malignant epilepsy showing no response to conventional antiepileptic drugs or hormone therapy were administered intravenous immunoglobulin (Endobulin, Immuno) at a dosage of 400 mg/kg per day on the 1st and 15th day and subsequently every three weeks for 6 months. 7 of these 15 patients showed IgG2 subclass deficiency. A significant reduction in attacks, or even absence of attacks was observed in 10 out of 15 children after six months of intravenous immunoglobulin therapy. Apart from one patient with ringchromosomopathy, all the children with IgG2 subclass deficiency responded to this therapy. The reduction of attacks after i.v. immunoglobulin therapy correlates with the improvement or normalization of the EEG findings. At present, the authors consider the number of patients still too small to make a final assessment, but they believe that intravenous immunoglobulin holds an important position in the treatment of malignant epilepsy in childhood.

[Selective deficiency of IgA]

The selective deficit of IgA is the most frequently acquired immunodeficiency. It is important because of this and the variability of the clinical presentation, which might be non-symptomatic or simply show several clinical features. The prognosis depends on the associated clinical affliction. There is no substitute treatment for this immunodeficiency, in which the immunoglobulins administration produces a paradoxical antibody formation against this, and adverse immunological reactions. We reviewed the immunodeficiency in this paper, highlighting the frequency, pathogenia, clinical diversity and therapy.

Patients with Igg subclass and/or selective antibody deficiency to polysaccharide antigens: initiation of a controlled clinical trial of intravenous immune globulin

Selective IgG subclass deficiencies and/or selectively impaired antibody responses to bacterial capsular polysaccharide antigens have been increasingly reported. In this report, 13 children with recurrent infections and deficient antibody responses to polysaccharide antigens are described. Serum IgG2 subclass concentrations were normal in all the patients, and two children had low IgG3 levels. Mean serum antibody concentrations to the capsular polysaccharide antigens of Streptococcus pneumoniae and Haemophilus influenzae were significantly decreased after immunizations, but antibody responses to diphtheria and tetanus toxoids were normal. The identification of children with selective antibody deficiencies and recurrent infections has prompted a multicenter, double-blind, placebo-controlled study to evaluate the efficacy and safety of intravenous immune globulin therapy in these patients.

Selective IgG subclass deficiencies in patients with recurrent sinopulmonary infections: report of two cases

Two patients with recurrent sinopulmonary infections and normal total serum immunoglobulin levels were found to have selective deficiencies in IgG subclasses. The serum of one patient contained abnormally low IgG2 and IgG4; and the other was deficient in IgG4. Both patients responded to the treatment with high dose intravenous immunoglobulin. The experiences on these two cases strongly suggest that IgG subclasses should be checked in patients with recurrent sinopulmonary infections in face of normal total immunoglobulins.

New and controversial uses of intravenous gamma-globulin

During the last few years the use of intravenous immunoglobulin (IVIG) has attracted increasing interest for the treatment of patients who do not have a classical humoral antibody deficiency syndrome. In certain situations this approach has revolutionized medical management, e.g. in immune thrombocytopenia. In other areas, such as in Kawasaki's syndrome, IVIG therapy have been shown to be highly beneficial in preventing long term disease sequelae by some investigators, but the field remains controversial. Conditions under which IVIG therapy has been shown to be of potential benefit are: (1) intractable childhood epilepsy; (2) autoimmune diseases, e.g. myasthenia gravis, systemic lupus erythematosus, idiopathic thrombocytopenic purpura, idiopathic neutropenia and aplastic anemia; (3) atopic allergy with IgG subclass deficiency including bronchial asthma; (4) in severe infections in combination therapy with antibiotics and as an antipyretic; (5) in Kawasaki's disease; (6) in multiple myeloma and chronic lymphocytic leukemia. Oral and intraventricular administration of IVIG have also been tried, the former for severe diarrhea and the latter to try to rescue the central nervous system from damage by a pathogen. Carefully controlled clinical trials are needed to establish the efficacy of gamma-globulin therapy in these and other conditions.

Intravenous immunoglobulin prophylaxis causing liver damage in 16 of 77 patients with hypogammaglobulinemia or IgG subclass deficiency

Sixteen of 77 patients (21 percent) with common variable immunodeficiency or IgG subclass deficiency contracted non-A, non-B hepatitis in association with intravenous infusions of immunoglobulin. The hepatitis seemed to run a more severe course in these patients than in non-immunodeficient patients. Twelve patients had clinical symptoms, and five died with hepatitis being the cause of death in two and a contributing factor in three. Liver biopsy specimens showed early chronic active hepatitis and cirrhosis. In addition to increases in liver enzymes, 13 patients had increases in alkaline phosphatase levels. All but two patients who contracted hepatitis had been given 50 mg/kg per week or more of intravenous immunoglobulin. Lymphocyte counts, T/B cell ratios, and T-lymphocyte function did not differ between those in whom hepatitis developed and those in whom it did not develop. The hepatitis was associated with more than one batch of a Swedish intravenous immunoglobulin, the immunoglobulin being derived from United States sources as well as from European plasma. Three previous brief reports in the literature have also associated non-A, non-B hepatitis with the intravenous infusion of various immunoglobulins. Biologic materials given to patients, including immunoglobulin, should, whenever possible, be prepared so as to ensure absence of viruses.

[Clinical relevance of immunoglobulin subclasses in children with chronic pulmonary diseases]

In 52 children (age 4-19.5 years; 17 female, 35 male) with chronic chest symptoms IgG-Subclass levels were measured by radial immunodiffusion techniques. Thirteen children had proven bronchiectasis, 22 chronic bronchitis and 17 steroid dependent asthma bronchiale. Cystic fibrosis, alpha-1-antitrypsin deficiency, tuberculosis and chronic foreign bodies were excluded in each patient; all of them showed normal levels of total IgG. Four children (3 with bronchiectasis, one with steroid dependent asthma bronchiale) had a complete lack if IgG4. In two children with chronic bronchitis one showed fluctuating levels of IgG2 and IgG4 and another deficiency of IgG3. All patients with an isolated IgG4 deficiency were treated with immunoglobulins. Of 3 patients with bronchiectasis one improved, two remained unchanged as shown by positive sputum cultures and of chronic chest symptoms. One patient with steroid dependent asthma bronchiale markedly improved during immunoglobulin therapy. It is concluded, that early screening of IgG subclass deficiency is indicated in all children with chronic chest symptoms.

The use of intravenous immunoglobulin for the treatment of infection: an overview

Immunoglobulin replacement therapy in the form of intravenous immunoglobulin (IVIgG) is clearly of benefit in primary hypogammaglobulinaemia and related disorders involving antibody deficiency. However, its use in the prevention of infection in other conditions is controversial and needs to be clarified. IVIgG therapy may be of benefit in selected patients with IgG subclass deficiency, and with a proven history of recurrent upper respiratory tract infections. IVIgG therapy may also benefit infants with AIDS and recurrent bacterial infections, but is only rarely of value in cases of adult AIDS. The use of 'normal' IVIgG from unselected blood donors to treat viral infections, infections due to gram negative organisms, or to neutralise endotoxin, is probably not indicated on theoretical and practical grounds, and because of the high cost. IVIgG preparations derived from plasma donations selected for high specific antibody levels to the relevant microorganism will probably be of greater benefit than normal IVIgG in patients with specific infections.

An investigation into the effect of the IgG antibody system on the susceptibility of IgA-deficient patients to respiratory tract infections

Serum IgG subclass concentrations and IgG-tetanus toxoid antibody (IgG-TTab) responses were measured in IgA-deficient patients with severe respiratory tract infections (n = 11), mild respiratory tract infections (n = 5) or no increased susceptibility to respiratory tract infections (n = 15). The severe infection group had lower IgG2 concentrations than the patients without infections (P less than 0.02) and was the only group with IgG2-deficient patients (36%). The number of sera in which IgG4 was not detected was higher in patients with severe infections than in both normal controls (45% vs 10%, P less than 0.01) and the other IgA-deficient patients (45% vs 20%), in part explained by a strong association with IgG2 deficiency. Subnormal IgG-TTab responses were demonstrated in 45% of patients with severe infections but in only one patient from each of the other two groups. Five patients with IgG2 deficiency and/or subnormal IgG-TTab responses were treated with gammaglobulin and apparently improved. There was a high serum concentration of IgG1 in 35% and IgG3 in 19% of the 31 patients, predominantly in those without severe infections. Thus a proportion of IgA-deficient patients have additional defects of IgG; IgG1 and IgG3 antibody responses may compensate for the IgA deficiency in asymptomatic patients.