The influence of immunization with live or killed Staphylococcus aureus vaccines on the early development of opsonizing and bactericidal factors in lymph and blood of sheep.

In order to obtain sensitive measurements on the synthesis of opsonins following immunization with live or killed S. aureus vaccines, lymph was collected from the efferent popliteal lymphatic duct of sheep during the early phase of the immune response. Lymph and blood serum were assayed for opsonizing capacity using 3H-labeled S. aureus. Within 1 hr after vaccination there was a rapid, transitory decrease in uptake by neutrophils of bacteria opsonized with lymph from sheep given the killed vaccine (Group 2). These results were in contrast to the relatively constant uptake rates of bacteria opsonized with lymph from sheep given the live vaccine (Group 1) and non-vaccinated controls (Group 3) at this time. At 72, 96, and 120 hr post-injection mean uptake values for bacteria opsonized with lymph from either vaccinated group were significantly greater than comparable values for controls. Mean uptakes for organisms opsonized with blood serum from Group 1 at 72 and 96 hr post-injection were significantly greater than comparable values for the control group. The percentage of viable neutrophil-associated bacteria decreased when lymph collected from animals in Group 2 in the first hour post-injection was used to opsonize the organisms. Percentages of viable, neutrophil-associated S. aureus for assays in which blood serum was used to opsonize remained relatively constant at around 45% for Groups 2 and 3. In contrast, however, values of viable neutrophil-associated bacteria for Group 1 decreased during the 120 hr after immunization.