Pediatric Pulmonology 11:44-48 (1991)

Clinical Observations on Lower Respiratory Tract Infections With Special Reference to Serum IgE Levels Yoko Nagayama, MD,' and Nobukiyo Sakurai, MD* Summary. To examine if the occurrence of wheezing among children with lower respiratory tract infections is associated with atopic predisposition, serum levels of IgE were determined for groups of children with or without wheezing, during infection with Mycoplasma pneumoniae or respiratory syncytial virus (RSV). In M. pneumoniae infection, more than 60% of wheezy children over 2 years of age showed a high IgE level (200 IUimL or more), while IgE levels were less than 200 IUimL in 73% of non-wheezy children. In RSV infection, the incidence of high IgE levels among wheezy children was nearly double that of non-wheezy children, although the difference was not significant. These results suggest that in children an allergic disposition is involved in the occurrence of wheezing during the course of lower respiratory tract infections. Pediatr Pulmonol. 1991; 11:44-48. Key words: Mycoplasmapneumoniae; RSV infections: wheezy vs. non-wheezy patients; affects of age and disease stage.

INTRODUCTION It has been reported that host factors, including atopic predisposition, may influence the severity of respiratory diseases, further relating to subsequent wheezing. '-" Agents that often induce wheezing have been reported to be respiratory syncytial virus (RSV) in young children and Mycoplasma pneumoniae in older children. In fact, there is a difference of age in children susceptible to infection with RSV or with M . pneumoniae. We have recently demonstrated that serum IgE levels increase in the acute phase of M . pneumoniae or RSV infection. '* IgE antibodies, specific to common allergens such as mite antigens, may also be detected in cases with a high IgE level.'* Based on these observations, we raised the question of whether wheezing during the course of a lower respiratory tract infection might be observed more commonly in children with a high IgE level than among those with a normal IgE level. We describe the relationship between serum IgE levels and clinical pictures, with an emphasis on wheezing in different age groups of children during M . pneumoniae or RSV infections.

''

MATERIALS AND METHODS Subjects The present study was performed in the pediatric clinics of two hospitals, the Asahi General Hospital in Asahi City and the Chiba University Hospital in Chiba City, Chiba Prefecture, Japan, for 7 years from April, 1979 to December, 1986. During these periods, many 0 1991 Wiley-Liss, Inc.

children suffering from lower respiratory tract infections visited one of the two hospitals. We identified lower respiratory infection when a patient showed one of following symptoms: a moist repetitive cough with or without sputum, abnormal sounds on auscultation, and wheezing or respiratory distress. Patients with abnormal shadows in the chest roentgenogram were regarded as having pneumonia. The characteristics of coughing were examined, eliciting a cough by rubbing the laryngeal area of the neck with our thumb. Moist repetitive cough was considered as an indication of lower respiratory infections. The diagnosed subjects were not selected by specified criteria; they had common types of M . pneumoniae or RSV infection. The total number of patients with confirmed infections was 476 with M . pneumoniae and 187 with RSV. These cases were divided into two groups by the presence or absence of wheezing during the acute infection. Age distributions of wheezy or non-wheezy cases with M . pneumoniae infection or RSV infection are summarized in Table 1. For M . pneumoniar infection, 1571186 (84.4%) cases of the wheezy group had pneumonia, From the Departments of Pediatrics, Chiba Children's Hospital, Chiba City' and Asahi General Hospital, Asahi City,' Japan. Received July 30, 1990; (revision) accepted for publication March 11, 1991. Address correspondence and reprint requests to Dr. Y. Nagayama, Department of Pediatrics, Chiba Children's Hospital, Hetacho 579- I , Chiba 280, Japan.

Lower Respiratory Tract Infections and Serum IgE

45

TABLE 1-Number of Patients, Symptoms, and Diagnosis by Age No. by age (years)

6

Total

40 37 6 0 26 24 2 5

52 48 8 3 60 50 8 3

41 33 3 4 66 58 6 3

36 28 5 2 136 I18 8 7

186 157 23 9 290 252 25 18

39 35

6 3 0

9

118

3 0

94

10

14

31 25 0 29 24

1

4

11 10 4

1

16

8 1

2 69 58 11

while 2521290 (86.9%) had pneumonia in the non- at 6 months, 40 IU/mL at 1-3 years, and 60 IU/mL at 4-9 wheezy group. For RSV infection, 9411 18 (79.7%) cases years; mean + 2 SD was 50 IU/mL at 6 months, 120 with pneumonia were in the wheezy group and 58/69 IU/mL at 1-3 year, and 150 IU/mL at 4-9 years. (84.1%) in the non-wheezy group. Statistical Analysis Diagnostic Procedures Statistical comparison was made by the chi square and M . pneumoniue was isolated by slightly modifying the analysis of variance techniques, in which a P value of < method of Chanock et a1.I3 as we have described it 0.05 was considered significant. previ0us1y.l~In addition to the first blood sample, the second one was whenever possible, also obtained within 3 weeks. Antibodies to M . pneumoniue in paired samples obtained in the acute and convalescent phase were RESULTS determined at the same time. Complement fixing (CF) IgE Levels of Children With M. pneumoniae antibody titers higher than 1:256, and antibody titers of Infection by Age indirect hemagglutination (IHA) higher than 1 :640 in the In wheezy children with M . pneumoniae infection, IgE acute phase, in addition to a fourfold rise in the paired levels increased as their age increased (Fig. 1). However, sera, were regarded as proof of occurrence of the wheezy cases with high IgE levels were observed even infection. Respiratory virus infections were also deter- among younger children, while wheezy cases with low mined by serological examinations. CF antibodies to M . IgE levels were rarely found in an older age group. Most pneumoniae, RSV, adenovirus, and influenza virus were of the children with past history of wheezy distress had a measured simultaneously. About two thirds of the paired high IgE. However, many patients who did not have a samples were examined for hemagglutination inhibiting history of wheezing but wheezed for the first time during (HI) antibodies to the parainfluenza virus. The diagnosis this infection also had a high IgE. A close relationship of these viral infections was made by a fourfold rise of CF between age and IgE levels was observed, although there were exceptions in infants (Fig. 1). On the other hand, or HI antibodies. IgE levels in the non-wheezy group varied from case to Measurement of Serum Total IgE case in each group (Fig. 2). Since in the non-wheezy Serum levels of total IgE were determined with the group many cases had normal IgE levels, there was no enzyme-linked immunosorbent assay, using the Pha- relationship between IgE and age. dezym P-RIST (Pharmacia, Sweden). l 2 Results of total To examine if any difference of IgE levels existed IgE of each case were compared to normal values among between the wheezy and non-wheezy group, the subjects Japanese children, determined by the same method as were divided into five groups by IgE levels, as shown in described above. l 5 Figure 3. The difference of IgE distributions between Approximate mean k SD levels of IgE were 20 IU/mL wheezy and non-wheezy cases was apparent in older

Nagayama and Sakurai

46 > 3000

> 3000

-

2000

-

0

0

0

0

P

.

. o

1000 -

-

800 600 500 400

800

300

300 -

200 -

200 -

600 500 400 -

E

\

2 w

-M

10080:

'

1

60 -

10or 80 60;

W 50 -3 40 30 -

50: 40

20 -

30

20

0

10 : 8-

6