The effects of breast- and bottle-feeding on serum immunoglobulin levels and specific antibody responses have been examined in 30 infants on five occasions from 6 days until 9 months of age. No significant differences were found on any sample occasion between the two feeding groups in total immunoglobulin levels of G, M and A classes or in class-specific antibody responses to tetanus toxoid vaccine. This suggests that the capacity of the two groups to make serum antibodies develops similarly. Concentrations of antibodies to commensal Escherichia coli 'O' lipopolysaccharide antigens, however, were significantly greater in the bottle-fed group, and it is suggested that this difference is due to an increase in the exposure of the systemic immune system to these gut antigens in the bottle-fed infants. There are several possible explanations for this increased exposure and the resulting effects on the infants' immune system. These experiments also illustrate a possible role of breast milk in stimulating the immune system.
SUMMARY Samples of saliva and nasal secretions were collected sequentially from 15 breast fed and 15 bottle fed infants on five occasions between 6 days and 9 months of age. Total immunoglobulin concentrations of G, M, and A classes, and class specific antibodies to tetanus toxoid and a pool of commensal strains of Escherichia coli were measured by solid phase radioimmunoassay and expressed per milligram of total protein. There were significant differences between feeding groups, which changed with age. Total IgM and IgA concentrations and IgA antibodies to E. coli were higher in the saliva and nasal secretions of breast fed infants at 6 days. There followed a rapid increase in IgM and IgA concentrations in secretions from all infants, and between 6 weeks and 9 months concentrations were higher in the saliva (but not in the nasal secretions) of the bottle fed group. There were no significant differences between the feeding groups for total IgG, specific G, M, and A antibodies to tetanus toxoid, and G and M antibodies to E. coli. These results suggest that breast feeding enhances secretory immunity in the early neonatal period only. By 6 weeks, local antigens are the main source of stimulation for production of immunoglobulin in the respiratory mucosa and thus may be obscuring any additional stimulation by growth factors in breast milk.The lower morbidity and mortality found in breast fed infants conmpared with bottle fed infants is a consequence not only of a reduction in the incidence of gastrointestinal tract infections but also of a
ABSTRACT. The effect of breast-feeding on the development of lymphocyte responsiveness in infants has been studied. Peripheral blood mononuclear cells from 15 breast-and 15 bottle-fed infants were obtained sequentially between 6 days and 9 months of age. A number of agents were used to stimulate the cells in vitro and the resulting proliferative responses were compared between the two feeding groups. A hanging drop microculture system using serum-free medium, enabled spontaneous proliferation and proliferative responses to several stimuli ( T and B cell mitogens, allogeneic lymphocytes, and antigen) to be studied a t a range of cell concentrations and days of culture. Significant age-related differences were found between the responses of cells from the two feeding groups. Spontaneous proliferation and proliferative responses to the T cell mitogen phytohaemagglutinin and the antigen tetanus toxoid were significantly greater in the breast-fed group a t the two earliest ages studied (6 days and 6 wk). Responses to mitogens which predominantly affect B cells, such a s pokeweed mitogen and Staphylococcus aureus (Cowan), were similar in both feeding groups a t this age. In contrast, from 3 to 9 months of age, responses of cells from bottle-fed infants were significantly greater to all stimuli than responses from breast-fed infants. One possible explanation for the higher level of proliferation by cells from newborn breast-fed infants, is that these infants may absorb the cell-growth factors and lymphokines known to be present in human colostrum and milk. These factors may stimulate T cells and/or their precursors in vivo. The subsequent greater responsiveness of peripheral blood mononuclear cells from the bottle-fed group a t 3 to 9 months of age appears to be due to a higher level of antigenic stimulation in vivo in this group. This could result from the greater intake of cow milk proteins or from the absence of the passive protective effect of the antimicrobial components in human milk. Breast-fed infants have a lower incidence of infections than bottle-fed infants (1-3). This has been attributed to a passive protective role of antimicrobial compounds in human milk, such as secretory IgA, acting locally within the gut of the newborn infant (4-6). More recently, interest has developed in other factors in colostrum and milk, such as epidermal growth factor (7, 8), interferon (9, 1 O), and prostaglandins ( 1 1, 12), which can influence cell growth and differentiation in vitro. It is possible that these growth factors and lymphokines in milk may actively enhance the development of the immune system of the breastfed infant, although an in vivo role for milk lymphokines has not yet been demonstrated. To investigate whether these lymphokines might be having an effect in vivo on the immune system of the breast-fed infant, we have studied the development of immune responses in breast-and bottle-fed infants sequentially from 6 days to 9 months of age.Mononuclear cell proliferation in vitro has frequently been used to assess ...
Low agglutinin titres to pertussis suspensions were found in 99% of sera from a group comprising healthy adults and non-vaccinated, non-infected infants of 1-6 months of age. These are attributable to agglutinins to heat-stable antigens and/or heat labile agglutinogen 1, and cross-absorption tests must be done on the sera in order to distinguish between the two. Agglutinins to agglutinogens 2 and 3 were found in only about 20% of adult sera. Bactericidal antibody was low in titre or absent in all sera from non-exposed individuals.Raised bactericidal antibody titres and the presence of agglutinins 2 and 3 were attributed to exposure to Bordetella pertussis antigens, either as vaccine or as infection. The variation, amongst both vaccinated and infected children, was very great. A vaccinated child who became ill responded to the infection in much the same way as a non-vaccinated child. We were unable to relate the immunity of the child to the titres either of agglutinins or of the bactericidal antibody.The protective ability of sera from vaccinated or infected children measured in mice against small, lethal brain infections was also unrelated to the state of immunity in the children, but this protective ability was correlated with the complement-mediated bactericidal antibody titres of the sera.The distribution of agglutinins, bactericidal antibody, and anti-haemagglutinin in serum IgG and IgM was different in vaccinated and infected children.
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