Congenital tuftsin deficiency.

The serum tuftsin activity in four different pediatric groups has been studied: (a) 20 premature infants, (b) 20 full-term infants, (c) 20 normal children (controls), and (d) 5 patients with recurrent and severe infections of the respiratory system, skin, and lymph nodes. The normal children as well as the premature and full-term infants had normal tuftsin activity. Tuftsin activity in the serum of the 5 patients in group (d) was absent. Cellular and humoral immunity in these patients was normal. All patients have been shown to have a mutant peptide that is strongly inhibitory to the normal tetrapeptide tuftsin. The clinical response of these patients to gamma-globulin was excellent.