Disappearance of immunoglobulins in acute phase of influenza A infection

Antigen-specific H1N1 influenza antibody responses in acute respiratory tract infections and their relation to influenza infection and disease course

BACKGROUND

Early antibody responses to influenza infection are important in both clearance of virus and fighting the disease. Acute influenza antibody titers directed toward H1-antigens and their relation to infection type and patient outcomes have not been well investigated.

OBJECTIVE

Using hemagglutination inhibition (HI) assays, we aimed to characterize the H1-specific antibody titers in patients with influenza infection or another respiratory infection before and after the H1N1-pandemic influenza outbreak. Among patients with acute influenza infection we related duration of illness, severity of symptoms, and need for hospitalization to antibody titers.

METHODS

There were 134 adult patients (average age 34.7) who presented to an urban academic emergency department (ED) from October through March during the 2008-2011 influenza seasons with symptoms of fever and a cough. Nasal aspirates were tested by viral culture, and peripheral blood serum was run in seven H1-subtype HI assays.

RESULTS

Acutely infected influenza patients had markedly lower antibody titers for six of the seven pseudotype viruses. For the average over the seven titers (log units, base 2) their mean was 7.24 (95% CI 6.88, 7.61) compared with 8.60 (95% CI 8.27, 8.92) among patients who had a non-influenza respiratory illness, p<0.0001. Among patients with seasonal influenza infection, titers of some antibodies correlated with severity of symptoms and with total duration of illness (p<0.02).

CONCLUSION

In patients with acute respiratory infections, lower concentrations of H1-influenza-specific antibodies were associated with influenza infection. Among influenza-infected patients, higher antibody titers were present in patients with a longer duration of illness and with higher severity-of-symptom scores.

Imbalanced anti-H1N1 immunoglobulin subclasses and dysregulated cytokines in hospitalized pregnant women with 2009 H1N1 influenza and pneumonia in Shenyang, China

Influenza virus can cause an acute respiratory illness of variable intensity. In our study, we describe the clinical and immunological characteristics of pregnant and nonpregnant women who were hospitalized with 2009 H1N1 influenza and pneumonia in Shenyang, China, from November 2009 to January 2010. Forty-two female patient infected with H1N1 were divided into groups according to pregnancy. Clinical data were collected. Cytokines and anti-H1N1 IgG subclasses were detected. We observed significant lymphopenia, hypoproteinemia, reduced CD4(+)T cell counts and CD4(+)/CD8(+) ratios, reduced anti-H1N1 IgG subclasses IgG2 and IgG3 constituent ratios, elevated C reactive protein and interleukin-10 levels with regard to nonpregnant H1N1 group. Compared with the healthy pregnant group, the pregnant H1N1 group showed elevated aspartate aminotransferase and glutamic alanine aminotransferase levels, an increased interferon-gamma and interleukin-10 levels and reduced anti-H1N1 IgG subclasses IgG2, IgG3 and IgG4 combination ratios. There was a statistically significant association between imbalanced anti-H1N1 immunoglobulin subclasses and dysregulated cytokines in pregnant women with H1N1 infection.