CHARACTERIZATION OF THE ANTIBODY-RESPONSE TO A HAEMOPHILUS-INFLUENZAETYPE-B CONJUGATE VACCINE IN CHILDREN WITH RECURRENT LOWER RESPIRATORY-TRACT INFECTION
K. Kristensen et al., CHARACTERIZATION OF THE ANTIBODY-RESPONSE TO A HAEMOPHILUS-INFLUENZAETYPE-B CONJUGATE VACCINE IN CHILDREN WITH RECURRENT LOWER RESPIRATORY-TRACT INFECTION, Allergy, 50(6), 1995, pp. 528-531
Children with recurrent lower respiratory tract infection (RLRI) may r
espond poorly to polysaccharide antigens. To examine how such children
respond to a polysaccharide coupled to a protein carrier, we immunize
d 15 children with RLRI aged 8-69 months and 15 carefully age-matched
healthy controls once with a Haemophilus influenzae type b (Hib) conju
gate vaccine. Total IgG subclasses, total antipolysaccharide Rib antib
odies, and antipolysaccharide Hib antibodies of IgM, IgG, IgA, and IgG
1-4 specificity were determined by ELISA, There were no significant di
fferences between the two groups in any single total IgG subclass, but
total Ige measured as the sum of all four subclasses was significantl
y lower in the children with RLRI than in the controls (P = 0.036). Be
fore vaccination, the children with RLRI had significantly less IgG an
tipolysaccharide Rib antibody than the controls (P = 0.005), whereas 1
month later they had significantly more IgM antibody (P = 0.038). No
other significant differences were found between the groups before or
after immunization with respect to antipolysaccharide Rib antibodies.
Since naturally occurring IgG antibodies are thought to be aquired par
tly as a consequence of antigenic stimulation on mucosal surfaces, we
hypothesize that the low level of specific IgG found before immunizati
on, as well as the low total Ige in the children with RLRI, may reflec
t an impaired ability to prime through mucosal surfaces. This is suppo
rted by our finding of an increased IgM response to Hib conjugate vacc
ine in these children, since this isotype predominates in the primary
immune response, i.e., in the absence of immunologic memory. In conclu
sion, children with RLRI can be protected against invasive Rib infecti
on as well as healthy children, but may have an immunodeficiency chara
cterized by defective ability to respond to antigenic stimulation on m
ucosal surfaces.