Invasive pneumococcal disease among infected and uninfected children of mothers with human immunodeficiency virus infection.

OBJECTIVE: To describe the incidence and clinical presentation of invasive pneumococcal disease in a cohort of children infected with human immunodeficiency virus (HIV) who were prospectively followed from birth, in comparison with uninfected children born to HIV-infected mothers and control children. DESIGN: Prospective follow-up of a cohort recruited at birth and born to mothers with known HIV status. The person-years analysis method used the occurrence of invasive pneumococcal disease as the end point. SETTING: Hospital-based clinic specializing in care of HIV-at-risk and HIV-infected children in Baltimore, Md. PARTICIPANTS: Forty-one vertically HIV-infected children, 128 uninfected children born to HIV-infected mothers, and 71 control children born to mothers with negative findings for HIV but with HIV risk factors. RESULTS: Among HIV-infected children, 10 episodes of invasive pneumococcal disease occurred during the first 36 months of life compared with 4 episodes among uninfected children and 1 episode among control subjects. The relative risk for HIV-infected children versus the combined uninfected and control groups was 12.6 with a 95% confidence interval (5.4, 28.8) and a p value for difference between groups of < 0.001. The incidence rate per 100 child-years of observation during the first 36 months of life was 11.3 for HIV-infected, 1.1 for uninfected, and 0.5 for control children. Clinical and laboratory variables were not useful in identifying HIV-infected children at risk for pneumococcal disease. CONCLUSION: Practical strategies to prevent pneumococcal disease among HIV-infected children need to be developed.

IgG receptors on the embryonic chick yolk sac.

Survival of the chick depends upon the transfer of maternal IgG from the egg yolk into the fetal circulation. Radiolabeled chicken IgG binds specifically to both fixed and unfixed yolk sac tissue from day 7 or 8 of embryogenesis through at least day 18. This binding is saturable, Fc-specific, pH-dependent, and reversible. Chicken Fc fragments and some heterologous IgGs compete with IgG binding, whereas bovine serum albumin, phosvitin, conalbumin, chicken IgM, and chicken Fab fragments do not. Eight-day embryos appear to have only a low affinity receptor, KD = 3.4 x 10(-7) M, but 18-day embryos have an additional high affinity receptor, KD = 3.0 x 10(-8) M. The membrane density of the low affinity receptor remains essentially constant throughout development.