Immunoglobulin A subclasses in infants' saliva and in saliva and milk from their mothers.
We sought to determine (1) the ontogeny of secretory IgA subclasses in saliva of breast- and formula-fed infants and (2) the influence of breast-feeding on the maturation of secretory salivary IgA subclasses. Secretory IgA and subclasses 1 and 2 concentrations were determined in saliva from 40 healthy, term infants from birth to age 18 months, and in parallel milk samples from the infants' mothers who were breast-feeding during the first 6 months after birth. Secretory IgA was detected in the neonates' saliva as early as 3 days after birth, increased rapidly during the next 6 months, but then stabilized at a level approximately one-sixth that of the mothers' salivary secretory IgA. Secretory IgA2 represented less than 15% of secretory IgA in saliva collected 2 weeks after birth but by 6 months represented 24.4% of secretory IgA, a value approaching that of the mothers' salivary secretory IgA2 (30.4%). This increase in the proportion of secretory IgA2 was temporally related to a reduction in the proportion of secretory IgA2 in milk throughout lactation. The secretory IgA concentration increased more rapidly during the first 6 months after birth in infants exclusively breast fed than in those exclusively bottle fed. We conclude that although secretory immunity is immature in infants, breast-feeding may aid in protection against pathogenic microorganisms by increasing the rate of mucosal IgA maturation.
Fitzsimmons
S P
SP
Department of Microbiology, Georgetown University Medical Center, Washington, D.C.
Evans
M K
MK
Pearce
C L
CL
Sheridan
M J
MJ
Wientzen
R
R
Cole
M F
MF
D001942:Breast Feeding; D005260:Female; D006801:Humans; D007071:Immunoglobulin A, Secretory / Q000032:analysis*; D007223:Infant; D007225:Infant Food; D007231:Infant, Newborn; D008297:Male; D008895:Milk, Human / Q000737:chemistry / Q000276:immunology*; D011446:Prospective Studies; D011506:Proteins / Q000032:analysis; D012463:Saliva / Q000737:chemistry / Q000276:immunology*
D007071:Immunoglobulin A, Secretory; D011506:Proteins