['The specific mechanisms regulating priming of T-cell immunity to common allergens during early childhood remain to be elucidated, though increasing evidence indicates that antigen-presenting cell function is impaired in childhood.', 'Examine the relationship between HLA-DR expression on monocytes and B cells, allergen-specific T-cell responses at birth, and clinical outcomes at 2 years of age.', 'Blood mononuclear cells were obtained from 36 healthy neonates who were followed up clinically to the age of 2 years. Expression of HLA-DR by monocytes and B cells was determined at baseline and after in vitro exposure to IFN-gamma, a cytokine that is known to upregulate the expression of HLA-DR. Mononuclear cells were stimulated with endotoxin or a panel of inhalant and food allergens, and cytokine responses and lymphoproliferation were determined after 1 and 5 days, respectively.', 'The magnitude of HLA-DR upregulation on IFN-gamma-stimulated cord blood CD14 + monocytes was consistently correlated with allergen-induced, but not mitogen-induced, lymphoproliferation at birth. HLA-DR upregulation on monocytes was also positively associated with endotoxin-induced IL-12 p70 synthesis (tau = 0.46; P < .001) but inversely related to mite- and ovalbumin-induced IL-13 synthesis ( P = .0006 and P < .003, respectively). HLA-DR expression on unstimulated cord blood monocytes was inversely associated with symptoms of atopic disease at the 2-year follow-up ( P = .015). In contrast, HLA-DR expression on B cells was not associated with these parameters of immune function.'] Is hLA-DR expression on neonatal monocytes associated with allergen-specific immune responses?