In vitro human reactivity to staphylococcal phage lysate.

The cell-mediated reactivity of normal individuals to staphylococcal phage lysate (SPL) were tested in vitro in the lymphocyte stimulation (LS) and leukocyte migration inhibition (LMI) assays. There were 95% positive responses in LS (stimulation ratio larger than or equal to 3 with p less than 0.01) and 67% positive responses in LMI (migration index less than or equal to 0.80). Enriched subpopulations of T and B lymphocytes were prepared with rosette formation and density gradient centrifugation. SPL stimulated lymphoproliferative responses in both T and B cell subpopulations whereas phytohemagglutinin (PHA) stimulated only the T cell subpopulation. Cord blood leukocytes were tested in the LS assay and 41% gave positive responses to SPL, 81% to PHA, and 17% with SLO. SPL appears to be a useful reagent for the in vitro study of cell-mediated reactivity, and may provide somewhat different information from that obtained with other mitogens or antigens.