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We evaluated the formation of specific and functional antibody in preterm infants born weighing less than 1500 g (mean 1088 g) and less than 32 wk gestational age (mean 28.8 wk). Plasma IgG antibody against tetanus and diphtheria toxoids were measured by an enzyme-linked immunosorbent assay. Opsonic activity of heat-inactivated plasma was measured using radiolabeled bacteria, adult polymorphonuclear leukocytes and exogenous human complement. In the presence of complement, the strain of coagulase negative staphylococcus used was opsonized by IgG antibody, and the strain of Escherichia coliby IgM. Geometric mean plasma levels of tetanus and diphtheria IgG antibody fell from birth to 4 months chronological age, but rose significantly by 9 months (approximately 2 months after the third dose of diphtheria, tetanus, pertussis vaccine). However, at 9 months they remained lower than the respective geometric mean levels in 9-month-old term infants (tetanus: p< 0.001; diphtheria: p= 0.02). The preterm infants' mean plasma IgG staphylococcal opsonic activity fell from birth to 2.5 months, but by 9 months was comparable to that of term infants of the same age. Mean IgM opsonic activity for E. coliwas very low at birth in both preterm and term infants. It rose with chronological age, correlating with the rise in total IgM (r= 0.48, p< 0.001) and by 9 months the mean preterm and term infants' levels of IgM opsonic activity for E. coliwere comparable. In the newborn period, the preterm infants' levels of plasma IgG tetanus and diphtheria antibody, but not IgG staphylococcal opsonic activity, correlated with their mothers' levels (tetanus: r= 0.84, p< 0.001; diphtheria: r= 0.86, p< 0.001; staphylococcal: r= 0.17, p= 0.38). Placentally transferred maternal tetanus, diphtheria, and opsonic staphylococcal IgG antibody did not inhibit the infants' subsequent antibody responses to the respective antigens. We conclude that the ability of preterm infants to form specific and functional antibody may place them at lower risk for infection than might be expected from their very low plasma levels of total IgG and IgM antibodies. In addition, the good correlation between newborn and maternal plasma levels of IgG antibody to tetanus and diphtheria toxoids, but not IgG-dependent staphylococcal opsonic activity, suggests preferential transport of some IgG antibodies across the placenta or, alternatively, that the function of some IgG antibodies may be impaired by placental transport.

Plasma immunoglobulin concentrations of premature infants of birth weight less than 1500 g were measured longitudinally from birth to 10 months chronological age. Infants were divided into two groups based on gestational age (group I: 25–28 wk; group II: 29–32 wk). In the 1st wk of life, plasma IgG levels correlated with gestational age (r= 0.5, p< 0.001). At 3 months chronological age, the geometric mean plasma IgG levels were 60 mg/dl in group I and 104 mg/dl in group II infants. Most infants remained hypogammaglobulinemic at 6 months with seven of 11 infants in group I and 13 of 21 infants in group II having plasma IgG levels below 200 mg/dl. In the 1st wk of life, plasma IgM concentrations were 7.6 and 9.1 mg/dl in groups I and II, respectively. They rose to 41.8 and 34.7 by 8 to 10 months of life. Plasma IgA concentrations were comparable for groups I and II in the 1st wk of life (1.2 and 0.6 mg/dl, respectively), but at 1 month of age group I infants had a transient increase in IgA which was not seen in the group II infants (4.5 versus1.9 mg/dl, respectively, p< 0.02). This transient elevation in IgA did not correlate with type or route of feeding or amounts of transfused blood. Group I and group II infants had comparable rates of infections prior to discharge from the nursery (p= 0.27). After discharge, the 43 preterm infants followed until 10 months chronological age had a significantly higher incidence of infections than 41 term infants (p= 0.04). In addition, the preterm infants had more lower respiratory infections after discharge than term infants (14 versus2, p= 0.003), and were rehospitalized more often for infection (8 versus0, p= 0.01). Despite severe prolonged hypogammaglobulinemia, none of the preterm infants had bacteremic illness after discharge from the nursery. This study provides normal age-group immunoglobulin values for the first 10 months of life in very small premature infants. The lack of invasive bacterial infections in this small group of preterm infants after discharge from the nursery suggests that further studies will be necessary to determine whether the hypogammaglobulinemia places these very low birth weight infants at risk for serious infection.

Polymorphonuclear leukocyte (PMN) function was evaluated in children with serous (SOM) and mucoid otitis media (MOM) and in an experimental model of acute purulent otitis media due to Streptococcus pneumoniaeusing chinchillas. Twenty-three of 100 children with SOM or MOM had depressed peripheral blood PMN chemotactic, bactericidal or chemiluminescence activity. Depressed PMN chemotactic acitvity was observed in 17(18%) of 97 children. Children whose middle ear effusions cultured Hemophilus influenzaewere more than twice as likely to have depressed PMN chemotactic activity as children whose effusions were sterile. Depressed PMN bactericidal activity was observed in seven (23%) of 30 children, and depressed PMN chemiluminescence activity was found in three (16%) of 19 children. Combined chemotactic and bactericidal dysfunction was observed in four (13%) of 30 children. All seven of the chinchillas with pneumococcal otitis media showed significantly depressed PMN chemotactic activity during the first week after inoculation, while only two of ten uninfected control chinchillas showed the same degree of chemotactic depression (P= .002). The association of H. influenzaeand S. pneumoniaewith depressed PMN function suggested that bacterial components of these microbes might have functional similarities. Both bacteria are surrounded by capsular polysaccharides which are known to persist in mammalian tissues for an extended period. It is possible that these or other components of H. influenzaeand S. pneumoniae, or even host factors generated during middle ear infection and inflammation, impair the PMN response to middle ear infection resulting in delayed bacterial killing and persistent middle ear effusion.

• Atopic dermatitis has been associated with recurrent infection and impaired neutrophil chemotaxis in some patients. In order to determine if dermatitis per se could decrease polymorphonuclear leukocyte (PMN) chemotaxis, we investigated chemotaxis in 13 patients with atopic dermatitis and no clinical or historical evidence of recurrent or severe infections. Most patients had extensive, but mild, disease. Leukocyte chemotaxis was measured by the Boyden chamber and agarose techniques. There was no difference between patient and control neutrophil chemotactic activity. These findings suggest that atopic dermatitis is not ordinarily associated with impaired PMN chemotaxis in the absence of generalized erythroderma or increased susceptibility to infection.(Arch Dermatol 114:544-546, 1978)

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