1049 Lymphokine Dependent Macrophage (MØ) Activation in Newborns

Abstract

The newborn (NB) suffers from severe infection with Tozoplasma gondii. resistance to which is mediated by lymphokine (MAF) induced Mø activation. Killing of Toxoplasma by recombinant interferon r (IFr) treated compared to control adult blood derived Mø (82% v s 20%), adult peritoneal Mø (96% v s 1%), NB blood derived Mø (79% vs 26%) and NB placental Mø (80% vs 11%) was significantly (p<0.05) increased; reoombinant IFα and IFβ were much less active. Supernatants of ConA stimulated adult blood mononuclear cells (MC) also increased anti Tozoplasma activity of these Mø and contained 841 ± 319 units/ml of IFr. In contrast, supernatants of NB cord and peripheral blood MC did not activate these Mø and had 108 ± 36 and 112 + 42 units/ml IF. Interleukins (IL 1 and 2 trigger IFr production by activated T cells. Adult and NB cord and peripheral MC produced 908 ± 157, 1501 ± 280 and 538 ± 170 units/ml IL2 and 822 ± 374, 1601 ± 521 and 1632 ± 785 units/ml of IL1 respectively. Purified IL1 increased IL2 production but not MAF production by NB peripheral MC; recombinant IL2 did not increase IF or MAF production by NB MC. IL2 receptors were detected by monoclonal antibody 2A3 on 67.3 ± 10.5%, 58.0 ± 9.9%, and 61.4 ± 70.0% of stimulated adult, NB cord and NB peripheral T cells. These data suggest that disassociation between IL2 and IFr production results in the failure of NB MC supernatants to activate Mø; this may contribute to the NB's susceptibility to intracel lular pathogens.

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