Monocyte chemotaxis was determined by an agarose technique in normal newborns, infants, older children, and adults and in selected patients. Monocytes were obtained from heparinized blood by Ficoll-Hypaque separation and exposed to zymosan treated serum as the chemotactic source. Newborn values (50 ± 33; ± 1 S.D.) were significantly different from adult values (216 ± 75, p<.005). An age related increase was noted (6 weeks to 2 yrs., 31 ± 25; 3 yrs. to 5 yrs., 71 ± 57; 6 yrs. to 10 yrs., 142 ± 64). Normal adult mean values were observed in the 11 to 16 year age group (214 ± 70).
Monocyte chemotactic defects have previously been described in several conditions. We have noted marked defects (>2 S.D.) in one patient with chronic mucocutaneous candidiasis and 4/29 patients with atopic dermatitis. In 8 patients on salicylate therapy, a mean decrease of monocyte chemotaxis of 25% was seen with salicylate levels >15 mgs% compared to a mean increase of 8% when neutrophil chemotaxis was concurrently measured. We also noted decreased monocyte chemotaxis in several seemingly normal subjects with absent delayed hypersensitivity skin tests to tetanus toxoid but normal in vitro lymphocyte transformation to tetanus.
These findings extend previous studies demonstrating maturational defects in human phagocytic cells, re-emphasize the possible role of defective monocyte chemotaxis in immunodeficient states, and suggest a possible mechanism for the anti-inflammatory effects of salicylates.