Quantitative measurements of Hemophilus influenzae type b capsular polysaccharide antibodies in Japanese children.
BACKGROUND
Hemophilus influenzae type b (Hib) infection has a high morbidity and mortality rate in children. The frequency of natural immunity against Hib in Japanese children is not known, and Hib vaccine has not yet been introduced in Japan.


METHODS
Anti-capsular polysaccharide-specific IgG (anti-CP) antibody titers were examined in serum samples from 100 children and 107 young adults who were not vaccinated against Hib, in serum samples from eight patients with Hib systemic infection and in 10 commercially available human immune globulin preparations on enzyme-linked immunosorbent assay.


RESULTS
A total of 44% (44/100) of Japanese children and all patients with Hib systemic infection in the acute phase did not have the minimum protective level of anti-CP antibodies (>0.15 microg/mL). The rate of natural Hib immunity was lowest in children under 1 year of age and gradually increased with age. Only 3.74% (4/107) of Japanese young adults did not have the minimum protective level of anti-CP antibodies. Analysis of 10 commercially available human immune globulin preparations indicated an average level of 28.25 microg anti-CP antibody/mL immune globulin (range 14.96-44.17 microg/mL).


CONCLUSIONS
Approximately half of Japanese children are not protected against Hib infection. Therefore, Hib vaccine should immediately be included as part of the routine immunization program in Japan. It was also found that all tested commercially available immune globulin preparations had high anti-CP titers. Well-controlled clinical trials of i.v. immune globulin administration for prevention and treatment of Hib systemic infection are needed in Japan.
Department of Pediatrics, Graduate School of Medicine, Chiba University, Chiba, Japan. ishiwada@faculty.chiba-u.jp
Naruhiko
N
Ishiwada
Chie
C
Fukasawa
Yukiko
Y
Inami
Haruka
H
Hishiki
Nobue
N
Takeda
Katsuo
K
Sugita
Yoichi
Y
Kohno
D000293:Adolescent; D000328:Adult; D000907:Antibodies, Bacterial / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006192:Haemophilus Infections / Q000276:immunology*; D019741:Haemophilus influenzae type b / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D007223:Infant; D007564:Japan; D008297:Male
D000907:Antibodies, Bacterial; D007074:Immunoglobulin G