cytochalasin-b and Streptococcal-Infections

Complement levels and complement activation are key determinants in streptococcus-induced inflammatory responses. Activation of macrophage functions, such as complement synthesis, by group B streptococci (GBS) was examined as a possible component of GBS-induced chronic inflammation. Using an enzyme-linked immunosorbent assay, secreted C3 from mouse macrophagelike cell lines (PU5-1.8 and J774A.1) was monitored after cultivation with GBS. Whole, heat-killed GBS (1 to 10 CFU per macrophage) of both type Ia and III strains induced 25 to 300% increases in secreted C3 in both cell lines after a 24-h cultivation. GBS-treated cell lines exhibited increases in secreted lysozyme (10%) and in cellular protein (25 to 50%). Inhibition of macrophage phagocytosis by cytochalasin B inhibited GBS stimulation of C3. Purified cell walls of GBS type III strain 603-79 (1 to 10 micrograms/ml) also enhanced C3 synthesis. Local enhancement of macrophage C3 production by ingested streptococci or by persistent cell wall antigens may serve to promote chronic inflammatory responses.

Topics: Animals; Cell Line; Cell Wall; Complement C3; Cytochalasin B; Inflammation; Macrophages; Protein Biosynthesis; Streptococcal Infections; Streptococcus agalactiae

Studies have shown that human neonates who develop group B streptococcal sepsis usually lack opsonic antibody (Ab) to their infecting strain and that these neonates may also have impaired polymorphonuclear leukocyte (PMN) function. The present study was designed to determine the efficacy of administration of PMNs or opsonic Ab-containing serum in protecting against group B streptococcal infection in a newborn rat model. After intraperitoneal (IP) injection of congruent to 5 X 10(6) streptococci, animals received separate IP injections of saline, serum lacking opsonic antibody (Ab negative), Ab positive serum or washed adult human PMNs (2 X 10(6)). The mortality rate in 55 neonatal rats infected with group B streptococci who received saline or Ab negative serum was 91%. In contrast, 40 animals who received adult human PMNs at the time of inoculation had a survival rate of 50% (P less than 0.001). Human serum containing opsonic antibody also provided significant protection against mortality in this model (survival rate 51%, P less than 0.001). Leukocytes from normal term neonates, stressed neonates, or ones pretreated with cytochalasin B offered les protection than did functional adult human cell (P less than 0.001).

Topics: Adult; Animals; Blood Transfusion; Cytochalasin B; Humans; Infant, Newborn; Infant, Newborn, Diseases; Neutrophils; Opsonin Proteins; Premedication; Rats; Streptococcal Infections; Streptococcus agalactiae