Use and interpretation of diagnostic vaccination in primary immunodeficiency: a working group report of the Basic and Clinical Immunology Interest Section of the American Academy of Allergy, Asthma & Immunology

Controversies in IgG replacement therapy in patients with antibody deficiency diseases

This Current perspectives article will review and highlight the importance of accurate diagnosis of patients who have failed to produce specific antibodies to naturally encountered foreign proteins or polysaccharides or after vaccination and the appropriate institution of immunoglobulin replacement therapy. The field of primary immunodeficiency disease (PIDD) has expanded remarkably since the early descriptions 6 decades ago. With greater recognition and advanced cellular and molecular diagnostic technology, new entities and single-gene defects in patients with PIDD are rapidly being defined. This, combined with treatment advances and newborn screening for severe combined immunodeficiency, has resulted in improved outcomes and survival and even permanent cures. Awareness of PIDD has also increased, but the guidelines for recognition remain to be validated. The zeal for registering and enrolling patients has potentially created a large body of "patients" treated with immunoglobulin replacement unnecessarily. The complexity, diversity, and availability of laboratory testing have brought awareness of PIDD to the forefront, but because of an absence of standardization of certain assays, concerns about the correct diagnosis and appropriate treatment have increased. We hope to refocus the discussion on identifying clear laboratory and clinical guidelines for the establishment of an accurate diagnosis of antibody deficiency, its rationale, and, where indicated, institution of safe treatment.

Autoimmune hemolytic anemia in a teenager: a wolf in sheep's clothing

This case report describes a 14-year-old boy who presented to the emergency department with symptoms of severe anemia. He was diagnosed with autoimmune hemolytic anemia, and on further investigation, it was noted that he had no functioning T cells. Despite no antecedent history of severe infection, he was worked up for a severe combined immunodeficiency, and was found to have a compound hypomorphic mutation in an enzyme responsible for recombination of the B- and T-cell receptors. He was subsequently diagnosed with severe combined immunodeficiency, presenting with autoimmunity, and received a bone marrow transplant. As our knowledge of the immune system continues to expand, we are learning that dysregulation can occur in any one of the complex immune pathways, and may have a variety of clinical presentations. A high index of suspicion for immune defects should be maintained in cases of atypical or severe infections, autoimmunity or malignancy, particularly by the general practitioner, who is often the first to encounter these challenging patients.

Specific antibody deficiency in children with recurrent respiratory infections: a controlled study with follow-up

Specific antibody deficiency (SAD) to unconjugated pneumococcal vaccine (PPV) is an established primary B cell immunodeficiency. The occurrence and natural history of SAD in children is unclear. We conducted an observational study to identify SAD in children with recurrent respiratory infections. Ninety-nine children, mean age 5·9 (range 2-16) years, with recurrent or severe infections were vaccinated with PPV; serum antibody concentrations for serotypes 4, 6B, 9V, 14, 18C, 19F and 23F were measured before and 2 weeks after vaccination with enzyme immunoassay. The retrospective control group consisted of 89 healthy children matched for age and gender. No children had received previous conjugated pneumococcal vaccine (PCV) or PPV. The structured history of infectious diseases of all participants was collected. Ten of 91 (11%) children (eight excluded due to immunoglobulin G subclass deficiency) with recurrent respiratory infections had SAD. In the control group, three children (3%) responded inadequately to PPV (P = 0·05). Most children with SAD also had many other minor immune defects. After 0·5-5 years (medium 3·8), eight children with SAD were revaccinated with PPV; five responded adequately and three inadequately. Two SAD children were revaccinated with PCV, one developed an adequate and one an inadequate response. Two children with SAD received treatment with intravenous immunoglobulin; the remaining eight children recovered without replacement therapy during the follow-up. SAD is common in young children with recurrent respiratory infections, but it is often transient and resolves itself within a few years without specific treatment.

Immunodeficiency in patients with 49,XXXXY chromosomal variation

Boys affected with 49,XXXXY sex chromosomal variation have been described to have high incidence of recurrent otitis media and asthma, the cause of which is unknown. We hypothesized that primary immunodeficiency occurs in patients with XXXXY aneuploidy. To investigate this, 31 boys with known 49,XXXXY were evaluated through a multidisciplinary clinic. Screening history was performed using the "10 Warning Signs of primary immunodeficiency" (Jeffrey Modell Foundation), as well as by history of atopic and autoimmune conditions. Of the 31 boys, 20 had at least two warning signs of primary immunodeficiency, and five had four or more signs. Sixteen had history of recurrent pneumonia, and 15 carried the diagnosis of asthma. Of the 10 who underwent immunologic screening, eight showed some evidence of impaired antibody responses to polysaccharide antigens, and one was diagnosed with specific antibody deficiency. These preliminary results suggest a high incidence of both atopy and antibody deficiency in boys with 49,XXXXY.

Recurrent respiratory infections, specific antibody deficiencies, and memory B cells

OBJECTIVES

To investigate the immunological phenotypes detected in children with recurrent upper and lower respiratory infections that have normal total immunoglobulin concentrations.

METHODS

A cohort of over 60 children with recurrent respiration infections was evaluated for specific antibody deficiencies (SAD) and for memory B-cell abnormalities. A control group of children without recurrent infections was also evaluated. Evaluation included a detailed history of immunizations with pneumococcal vaccines; determination of IgM, IgG, IgA, and IgE concentrations; measurement of anti-pneumococcal polysaccharide antibody levels by ELISA and expression of CD27, IgD, and IgM on peripheral CD19(+)B cells by flow cytometry to determine the proportions of naive, IgM-memory B cells, and class-switched memory B cells.

RESULTS

Patients were classified as having a SAD to either pure polysaccharides (PPV-SAD) or to conjugate polysaccharides (PCV-SAD) based on the number of polysaccharides to which they developed an adequate antibody response. A normal response to only 2 or fewer of 7 PCV or PPV serotypes was considered as evidence of SAD. Forty-one patients without SAD and 26 with SAD were identified. IgM-memory B cells were low in 3 of 41 patients without SAD; in 3 of 5 PPV-SAD patients; and in 10 of 21 PCV-SAD patients. Class-switched memory B cells were low in 19 of 41 patients without SAD; in all 5 patients with PPV-SAD; and in 11 of 21PCV-SAD patients.

CONCLUSIONS

Patients with recurrent infection with or without SAD may have low IgM- and/or class-switched memory B cells. Ongoing research aims to determine the prognostic implications of these differences in patients with SAD.