Interleukin-1 secretion by blood monocytes of septic premature infants.

This study examined lipopolysaccharide (LPS) induced in vitro secretion of interleukin-1 (IL-1) by peripheral blood monocytes from pre-term infants with and without sepsis. Thirteen pre-term babies were tested; eight were completely healthy and five suffered from six episodes of sepsis. The latter group was tested both in the acute septic phase and in the convalescent period. IL-1 secretion by monocytes derived from septic pre-term infants was lower, but not significantly different from healthy pre-term infants (7.1 +/- 1.0 U/ml versus 8.1 +/- 0.9 U/ml, respectively). IL-1 secretion by monocytes of eight control full-term babies was in the same range (8.4 +/- 0.6 U/ml). In the convalescent period IL-1 secretion by monocytes from septic pre-term babies increased (9.0 +/- 0.3 U/ml) and was significantly higher than values measured during acute infection (p less than 0.05). Septic premature babies were also found to have higher absolute blood neutrophil concentration (p less than 0.001), but their body temperature did not increase along the infectious stage. The decreased secretion of IL-1 by monocytes from pre-term babies in the acute phase of infection compared to the convalescent period may have contributed to their inability to mount appropriate immunological as well as inflammatory responses. Sepsis promoting IL-1 production in vivo may have limited the monocytes' capacity for LPS stimulated IL-1 synthesis in vitro.