Selective IgG Subclass Deficiencies and Antibody Responses to Pneumococcal Capsular Polysaccharide Antigen in Adult Community-acquired Pneumonia

Abstract

We measured the serum concentrations of IgG subclasses in healthy subjects (n = 26) and in patients with community-acquired pneumonia (CAP) on admission (n = 38), at recovery (n = 21), and 9 months after admission (n = 19). Then, in 8 of the control subjects and 15 of the patients, we measured IgG subclasses and mean serum antibody concentrations of pneumococcal capsular polysaccharides before and 3 wk after immunization with a pneumococcal vaccine. Compared to the control subjects, the serum concentration of the IgG2 subclass was lower at admission in patients with CAP of bacterial or unknown cause (p less than 0.005). Concentrations of IgG subclasses in patients did not differ between admission and recovery, or between admission and 9 months later. After vaccination, in both control subjects and patients, there was an increase in the concentrations of IgG2 subclasses (p = 0.01) and antipneumococcal antibodies (p less than 10(-4)). We show that serum IgG2 concentration in patients with CAP of bacterial or unknown cause is lower than in healthy subjects and remains lower for several months. After immunization with a pneumococcal vaccine, the increase in serum concentrations of IgG subclasses and antipneumococcal antibodies in patients does not differ from those in control subjects.

Serum levels of immunoglobulins and severity of community-acquired pneumonia

“…However, in a previous population-based case–control study, with 171 cases and 90 controls matched by age and sex, all immunoglobulins were significantly lower in cases than in controls, mainly total IgG and IgG2 17. In contrast to the study of Herer et al ,20 80% of patients normalised immunological levels in the convalescent phase (after 30 days).…”

“…In contrast to findings in the study of Feldman et al ,19 we found that low levels of total IgG, IgG1 and IgG2 may be prognostic factors of mortality and are more frequently observed in patients admitted to the ICU. In 1990, Herer et al 20 reported that serum levels of IgG2 in patients with CAP (n=38) of bacterial or unknown aetiology were lower than in healthy subjects (n=26), remaining low 9 months later. A comparison with healthy subjects was not made in our study.…”

Analysis of immunoglobulin isotype levels in acute pneumococcal bacteremia and in convalescence

“…Of nine patients with levels below normal of one or more of the IgG subclasses, IgG2 levels.were low in eight patients. Herer et al (9) found a significant decrease in IgG2 but not in the other subclasses. It is known that patients with a combined IgAIgG2 deficiency are more prone to frequent respiratory infections than patients with an isolated IgA deficiency (14).…”

“…In patients with immunoglobulin deficiencies, infections of the respiratory tract are common (5,6). IgG2 is the most important immunoglobulin subclass for defence against pneumococci (7,8), and IgG2 levels have been shown to be lower in patients with community-acquired pneumonia of bacterial origin than in healthy control subjects (9). In this study we analyzed the levels of immunoglobulins, including IgG subclasses, in patients during and after pneumococcal bacteremia.…”

Comparison of Immunoglobulin G Subclass Concentrations in Severe Community-Acquired Pneumonia and Severe Pandemic 2009 Influenza A (H1N1) Infection

“…IgG2 deficiency has been associated with recurrent pneumonia (3); however, there are limited data on IgG subclass concentrations in previously well adults with CAP. Herer et al (6) found low IgG2 concentrations in 38 hospitalized CAP patients; however, this difference was observed in patients with bacterial, not viral, pneumonia and pneumonia severity was not reported. In a singlecenter prospective study, Feldman et al (4) found that 21% of 19 adults admitted to the intensive care unit (ICU) with severe CAP were deficient in IgG1 or IgG2-a substantially lower percentage than the 62% we identified among 65 ACAPS patients.…”