Neutrophil and monocyte function in pediatric patients with recurrent pneumonias: a longitudinal study.

Peripheral neutrophil and monocyte function was studied in 24 pediatric patients with recurrent lower respiratory tract infections referred to the University of New Mexico Pediatric Pulmonary Center. The age range of the patients was 4 months to 12 yr with a mean of 32 months. Depressed neutrophil chemiluminescence activity was observed in 46% of the 24 patients studied, depressed neutrophil chemotactic responsiveness was observed in 27% of 22 patients, depressed monocyte chemiluminescence was observed in 31% of 16 patients, and depressed monocyte chemotaxis was observed in 45% of 20 patients. Of the 11 patients with abnormal neutrophil chemiluminescence, 56% also had abnormal neutrophil chemotaxis. Eight of the 11 patients with depressed neutrophil chemiluminescence were retested 9 months to 1 yr after initial testing, and in 5 of the 8, chemiluminescence had returned to normal, whereas in the other 3, it had remained depressed. The 3 whose neutrophil chemiluminescence remained depressed continued to have repeated pneumonias as did one patient whose values had returned to normal. The estimated probability of return to normal for the neutrophil chemiluminescence after 1 yr was 0.625. These findings suggest that because the ability to move functionally intact neutrophils and monocytes into the lung is important for effective lung defense, that the defective phagocytic cell function defined here may be directly related to the recurrent pneumonias found in these pediatric patients.