Human alveolar macrophages (AMs) migrated toward and aggregated to C5a but not toward C5a-deficient serum. Human AMs from cigarette smokers migrated significantly farther than did AMs from nonsmokers. Human AMs phagocytized Escherichia coli opsonized with activated C3. Immunoglobulin G was not required for phagocytosis. Human AMs demonstrate chemotaxis and aggregation to C5a. Further, human AMs can phagocytize bacteria coated with activated C3.

The detection of antibody to S aureus in human serum can aid in the management of staphylococcal diseases [1]. RIAs and ELISAs can detect low levels of antibody and demonstrate increased antibody production during serious staphylococcal infections [2,3]. We compared four S aureus constituents--cell-wall peptidoglycan and teichoic acid, and extracellular alpha-toxin and nuclease--as antigens in a sensitive ELISA. The value of testing more than a single serum sample was also determined. Elevated IgG antibody to peptidoglycan, present in one or more serum samples of 13 (50%) of 26 patients with complicated bacteremia, was found to be the most sensitive test. All 26 patients had a significant IgG antibody response to peptidoglycan. Three (27%) of 11 patients with uncomplicated bacteremia had elevated levels of antibody to peptidoglycan in their serum, and seven (64%) showed a significant change in titer when serial serum samples were tested. Maximum detection rates for the other antigens in complicated and uncomplicated bacteremia were, respectively, 62% and 37% for teichoic acid, 38% and 37% for nuclease, and 54% and 13% for alpha-toxin. In single serum samples, the detection rate for all four antigens marginally improved the results, with detection rates of 62% and 36% for complicated and uncomplicated bacteremia, respectively. Cross-reactive antibody to peptidoglycan but not to the other three antigens was present in six (75%) of eight patients with long-standing subacute bacterial endocarditis due to either viridans streptococci or Staphylococcus epidermidis (data not shown).(ABSTRACT TRUNCATED AT 250 WORDS)