Age-dependent effects of aminobutyryl muramyl dipeptide on alveolar macrophage function in infant and adult Macaca monkeys.

Abstract

We compared the antimicrobial function of alveolar macrophages (AM) from adult and 3- to 5-wk-old infant primates (Macaca nemestrina) and the effects of the immunomodulator, aminobutyryl muramyl dipeptide (abu-MDP) on this function. Phagocytosis of Staphylococcus aureus (SA) and group B streptococcus (GBS) by adult and infant AM was comparable. Adult and infant AM killed SA equally within 15 min of incubation; however, after 45 min, with phagocytosis of additional bacteria, adult AM had greater bactericidal activity (p less than 0.01). The bactericidal activity of infant and adult AM against GBS was comparable after 45 min of incubation; infant AM had slightly but significantly greater bactericidal activity with short incubation (15 min; p less than 0.025). The bactericidal activity of abu-MDP-treated infant AM against SA (p less than 0.01) and GBS (p less than 0.05) was greater than that of untreated infant AM and untreated or abu-MDP-treated adult AM. The abu-MDP did not significantly (p greater than 0.2) enhance the antimicrobial activity of adult AM. Catalase, but not superoxide dismutase or mannitol, significantly (p less than 0.005) increased survival of GBS in infant AM; this effect was comparable in abu-MDP-treated and in untreated AM. The abu-MDP-treated infant, but not the adult AM, released more acid phosphatase when triggered by opsonized zymosan than did untreated AM, but superoxide anion release by infant or adult AM was not affected by incubation with abu-MDP.(ABSTRACT TRUNCATED AT 250 WORDS)