Serum levels of immunoglobulins and severity of community-acquired pneumonia

Abstract

InstructionThere is evidence of a relationship between severity of infection and inflammatory response of the immune system. The objective is to assess serum levels of immunoglobulins and to establish its relationship with severity of community-acquired pneumonia (CAP) and clinical outcome.MethodsThis was an observational and cross-sectional study in which 3 groups of patients diagnosed with CAP were compared: patients treated in the outpatient setting (n=54), patients requiring in-patient care (hospital ward) (n=173), and patients requiring admission to the intensive care unit (ICU) (n=191).ResultsSerum total IgG (and IgG subclasses IgG1, IgG2, IgG3, IgG4), IgA and IgM were measured at the first clinical visit. Normal cutpoints were defined as the lowest value obtained in controls (≤680, ≤323, ≤154, ≤10, ≤5, ≤30 and ≤50 mg/dL for total IgG, IgG1, IgG2, IgG3, IgG4, IgM and IgA, respectively). Serum immunoglobulin levels decreased in relation to severity of CAP. Low serum levels of total IgG, IgG1 and IgG2 showed a relationship with ICU admission. Low serum level of total IgG was independently associated with ICU admission (OR=2.45, 95% CI 1.4 to 4.2, p=0.002), adjusted by the CURB-65 severity score and comorbidities (chronic respiratory and heart diseases). Low levels of total IgG, IgG1 and IgG2 were significantly associated with 30-day mortality.ConclusionsPatients with severe CAP admitted to the ICU showed lower levels of immunoglobulins than non-ICU patients and this increased mortality.

Low Levels of Immunoglobulins and Mannose-Binding Lectin Are Not Associated With Etiology, Severity, or Outcome in Community-Acquired Pneumonia

“…Feldman et al could not find any differences in IgG subclass levels between 66 non-ICU and ICU patients with CAP [ 31 ]. By contrast, a recent Spanish study of 418 CAP patients showed a significant association between low Ig levels (IgG/IgG1) in patients with a CURB-65 severity score of 4 and 5, in ICU patients vs non-ICU patients (IgG/IgG1/IgG2), and with 30-day mortality (IgG/IgG1/IgG2) [ 13 ]. Low levels of IgG2 have been observed in patients with severe H1N1 influenza in China [ 32 ] and Australia [ 10 , 11 ].…”

Immunoglobulins concentration and B cell counts as severity markers in adult community-acquired pneumonia

“…[ 4 ] The few available studies measuring Igs in adult CAP have shown lower levels in patients as compared with controls and also in hospitalized vs ambulatory cases. [ 5 ] However, they disagree on the class/subclass of Igs compromised. [ 5 – 7 ] The use of antibodies level as a severity biomarker in these patients is also controversial, and while some studies found no relationship, [ 6 , 8 , 9 ] others have associated low IgG or IgA levels with severity and/or lethality.…”

“…[ 5 ] However, they disagree on the class/subclass of Igs compromised. [ 5 – 7 ] The use of antibodies level as a severity biomarker in these patients is also controversial, and while some studies found no relationship, [ 6 , 8 , 9 ] others have associated low IgG or IgA levels with severity and/or lethality. [ 5 , 10 , 11 ]…”

Efficacy and safety of trimodulin, a novel polyclonal antibody preparation, in patients with severe community-acquired pneumonia: a randomized, placebo-controlled, double-blind, multicenter, phase II trial (CIGMA study)

“…IgM plays a critical role in the immediate defense against severe bacterial infection. Reduced IgM levels have been observed in patients with CAP, sepsis, and severe pandemic influenza; consequently, interest in add-on therapy with IgM-enriched preparations has increased [ 10 – 12 ]. The evidence for IgM-enriched Ig preparations in patients with severe sepsis and septic shock is incompletely understood, although systematic reviews have generally concluded that IgM-enriched Ig preparations are associated with a reduction in mortality [ 6 , 7 ].…”