Transient T-cell abnormality in a selective IgM-immunodeficient patient with Brucella infection

Selective IgM Deficiency: Evidence, Controversies, and Gaps

Selective Immunoglobulin M deficiency (SIgMD) has been recently included in the inborn errors of immunity (IEI) classification by the International Union of Immunological Societies Expert Committee. The understanding of SIgMD is still extremely limited, especially so in cases of SIgMD in the pediatric population. The epidemiology of SIgMD in the pediatric population is still unknown. The pathogenesis of SIgMD remains elusive, and thus far no genetic nor molecular basis has been clearly established as a definitive cause of this primary immunodeficiency. Recurrent respiratory infections represent the main clinical manifestations in children, followed by allergic and autoimmune diseases. No conclusive data on the correct therapeutic management of SIgMD are available. Although, for most SIgMD patients, Ig replacement therapy is not required, it may be recommended for patients with significantly associated antibody deficiency and recurrent or severe infections. Prophylactic antibiotics and the prompt treatment of febrile illness are crucial. There is insufficient evidence on the prognosis of this condition. Therefore, further studies are required to define the disease trajectories and to increase our understanding of the molecular mechanisms underlying SIgMD in order to facilitate a better clinical, immunological, and prognostic characterization of the condition and develop tailored therapeutic management strategies.

Selective IgM Deficiency-An Underestimated Primary Immunodeficiency

Although selective IgM deficiency (SIGMD) was described almost five decades ago, it was largely ignored as a primary immunodeficiency. SIGMD is defined as serum IgM levels below two SD of mean with normal serum IgG and IgA. It appears to be more common than originally realized. SIGMD is observed in both children and adults. Patients with SIGMD may be asymptomatic; however, approximately 80% of patients with SIGMD present with infections with bacteria, viruses, fungi, and protozoa. There is an increased frequency of allergic and autoimmune diseases in SIGMD. A number of B cell subset abnormalities have been reported and impaired specific antibodies to Streptococcus pneumoniae responses are observed in more than 45% of cases. Innate immunity, T cells, T cell subsets, and T cell functions are essentially normal. The pathogenesis of SIGMD remains unclear. Mice selectively deficient in secreted IgM are also unable to control infections from bacterial, viral, and fungal pathogens, and develop autoimmunity. Immunological and clinical similarities and differences between mouse models of deficiency of secreted IgM and humans with SIGMD have been discussed. Patients with SIGMD presenting with recurrent infections and specific antibody deficiency responses appear to improve clinically on immunoglobulin therapy.

Selective IgM Deficiency: Clinical and Laboratory Features of 17 Patients and a Review of the Literature

PURPOSE

Primary selective IgM deficiency (sIgMD) is a primary immunodeficiency with unclear pathogenesis and a low number of published cases.

METHODS

We reviewed clinical and laboratory manifestations of 17 sIgMD patients. Serum IgM, IgG, and its subclasses, IgA, IgE, antibodies against tetanus toxoid, pneumococcal polysaccharides and Haemophilus influenzae type b, isohemagglutinins, and T and B lymphocyte subsets, expressions of IgM on B cells and B lymphocyte production of IgM were compared with previously reported case reports and a small series of patients, which included 81 subjects in total.

RESULTS

We found that some patients in our cohort (OC) and published cases (PC) had increased IgE levels (OC 7/15; PC 21/37), decreased IgG4 levels (OC 5/14), very low titers of isohemagglutinins (OC 8/8; PC 18/21), increased transitional B cell counts (OC 8/9), decreased marginal zone B cell counts (OC 8/9), and increased 21^low B cell counts (OC 7/9). Compared with the PC (20/20), only two of five OC patients showed very low or undetectable production of IgM after stimulation. A majority of the patients had normal antibody production to protein and polysaccharide antigens, basic lymphocyte subset counts, and expression of surface IgM molecules on B cells.

CONCLUSIONS

Low IgM levels are associated with various immunopathological disorders; however, pathogenic mechanisms leading to decreased IgM serum level in selective IgM deficiency remain unclear. Moreover, it is difficult to elucidate how strong these associations are and if these immunopathological conditions are primary or secondary.

The prevalence of Selective Immunoglobulin M Deficiency (SIgMD) in Iranian volunteer blood donors

BACKGROUND

Selective Immunoglobulin M Deficiency (SIgMD) is known as a rare primary immunodeficiency characterized by an isolated deficiency of serum IgM. Other immunoglobulin levels and T-cell immunity are usually normal; although IgE may be elevated. SIgMD can be asymptomatic or with various bacterial and viral infections. It can also be associated with autoimmune diseases or malignancies. In the present study, we report for the first time, the prevalence of SIgMD in Iranian healthy adult population.

MATERIALS AND METHODS

A total of 3436 healthy donors were examined in the study; from August, 2006 to April, 2008. Serum IgM concentration was measured using the nephelometric method. We considered serum IgM less than 30 mg/dl as IgM deficiency.

RESULTS

Among 3436 participants, 65% were male and 34% were female; aging from 17 to 72 years (38.18±10.78). Thirteen individuals were detected as IgM deficient subjects with the male to female ratio of 11/2, the prevalence of 0.37% and the frequency of 1/265. The mean serum IgM level was 24±4.56 (16-29 mg/dl) in these cases. Among 13 IgM-deficient subjects, 7 cases were available for evaluating the clinical manifestations. In addition to atopic dermatitis which was the most common symptom in these patients, others were allergic rhinitis, food allergy, urinary tract infection and skin fungal infection. Two patients had no history of infectious disease or atopic conditions.

CONCLUSION

In the present study we could determine the prevalence of SIgMD in our adult population (0.37%). The most common comorbid condition was atopy. Neither severe or life-threatening infections, nor autoimmune diseases (based on their history; the antibody screening was not performed as part of this study) or malignancies were found in these patients. Further evaluation is recommended to elucidate the prevalence of SIgMD among patients with recurrent infections.

Selective IgM deficiency in an adult presenting with Streptococcus pneumoniae septic arthritis

Septic arthritis caused by Streptococcus pneumoniae is uncommon. Most of the patients who have invasive pneumococcal infection have underlying diseases associated with impaired immune function. We report a case of polyarticular pneumococcal septic arthritis in a previously healthy adult as the first manifestation of selective immunoglobulin (Ig)M deficiency. The patient had no evidence of autoimmune disease or malignancy. Serum IgG, IgA, and complement levels were normal. Numbers of lymphocyte subsets were in normal range except that of CD4+ cells, which was slightly low. Invasive pneumococcal disease in a healthy adult should lead to further investigation for underlying diseases including primary immunodeficiencies.

Serum levels of soluble interleukin-2 receptor alpha (sIL-2Rα) as a predictor of outcome in brucellosis

OBJECTIVES AND METHODS

Brucellosis is characterized by chronicity and relapses despite efficacious treatment. Cytokines and especially the Th1/Th2 balance may be involved in the susceptibility or resistance to the Brucella species. In order to identify predictors of treatment outcome, we measured the pre and posttreatment levels of serum interleukin-2 (IL-2) and soluble IL-2 receptor alpha (sIL-2Ralpha) in 20 children with brucellosis. All children were treated for 6 weeks and three of them (15%) presented with a relapse at 2, 3 and 8 months after treatment had ended.

RESULTS

Serum IL-2 levels, both pretreatment and posttreatment, did not significantly differ between patients and controls. By contrast, pretreatment sIL-2Ralpha levels were significantly higher in patients (P< or =0.0001) than in controls. sIL-2Ralpha levels significantly declined (P<0.001) after the 6-week antibiotic regimen in the 17 children who subsequently had a good outcome without relapses, but not in the three patients who relapsed.

CONCLUSIONS

A decline in serum sIL-2Ralpha levels might be used as a marker of treatment efficacy in brucellosis.

Brucellosis in patients infected with the human immunodeficiency virus

Brucellosis has been described rarely in patients infected with HIV, despite the fact that eradication of intracellular brucellae is largely dependent on cell-mediated immunity. The characteristics of all patients with HIV infection and brucellosis seen in seven Spanish hospitals are reported. Since the beginning of the AIDS epidemic, 12 HIV-infected patients were diagnosed with brucellosis (8 with cultures positive for Brucella spp., 4 with high anti-Brucella antibody titers). Most patients were male and intravenous drug users. Eleven patients had no symptoms of HIV infection when first diagnosed with brucellosis and had relatively preserved cellular immunity (median CD4 + cell count 588, range 136-1006). There was a clear epidemiologic antecedent for acquisition of brucellosis in 11 patients. Clinical symptoms included fever, arthromyalgia, and sweating in all patients; four patients presented with focal disease. All patients had high agglutinin titers, and eight of nine had cultures positive for Brucella. Therapy with doxycycline and streptomycin was curative in all cases. Two patients experienced a recurrence of symptoms after initial treatment, although no microbiological relapses were documented after a median follow-up period of 18 months. HIV infection does not seem to increase the incidence of brucellosis. Since most cases occur in asymptomatic patients with relatively preserved immunity, the epidemiology, clinical presentation, diagnosis, response to therapy, and outcome are similar to those observed in non-HIV infected patients.

T-cell abnormalities in antibody deficiency syndromes

We studied two patients with hypogammaglobulinaemia, three with selective IgA deficiency, and four with selective extreme IgM deficiency for T-cell abnormalities in the circulating blood. Most patients had altered CD4+ helper/inducer and CD8+ suppressor/cytotoxic T-cell subsets, and an elevated percentage of HLA-DR+ and interleukin 2 (IL-2) receptor+ antigens on lymphocytes. One patient with the selective IgA deficiency had an absence of CD4+ T cells in blood. The lymphocytes of eight patients showed a diminished proliferative response and deficient IL-2 production in response to stimulation with phytohaemagglutinin or concanavalin A. The three patients with selective IgM deficiency were found to have a defective T-cell abnormality in IgM synthesis by B cells. It is interesting that CD8+ T cells of the two patients with IgM deficiency demonstrated suppressor cell function for IgM synthesis by the normal B and T cells.