Intracellular colony forming units (CFU) were determined after gentamicin treatment by serial plating and the internalization rate of the antibody-coated relative to the uncoated bacteria was KU-60019 order calculated. As expected, the Lm-spa- strain (which is InlAB-negative) was not internalized by

4T1, 4T1-HER2, SKBR3 or SKOV3 cells regardless whether these bacteria were incubated with Cetuximab or Trastuzumab. Raw CFU data of intracellular bacteria used for calculation of (a) and (b) is shown in (c) and (d). Raw CFU data of intracellular bacteria used for calculation of Figure 2a and Figure 2b is shown in (e) and (f). (PDF 32 KB) Additional file 2: Immunofluorescence microscopy showing the replication of Lm-spa + in the cytosol of SK-BR-3 cells. SK-BR-3 cells were infected at a MOI 10 with L. monocytogenes strains

ΔtrpS × pSP0-P actA -gfp (a), Lm-spa – × pSP0-P actA -gfp (b) and Lm-spa + × pSP0-P actA -gfp (c) preincubated with 1 × PBS (i-iii) or Trastuzumab (iv-vi) and GFP-expression was monitored by fluorescence microscopy at the indicated time points. Bright field and fluorescence overlay images are shown. The L. monocytogenes control strain ΔtrpS × pSP0-P actA -gfp shows the typical intracellular life cycle independent of preincubation with Trastuzumab (a). L. monocytogenes strain Lm-spa – × pSP0-P actA -gfp is unable to infect SK-BR-3 cells click here as expected (b). L. monocytogenes strain Lm-spa + × pSP0-P actA -gfp infects cells and replicates in the cytosol only after preincubation with Trastuzumab (c). Because of the aroA deletion Lm-spa + × pSP0-P actA -gfp hardly spreads to neighboring cells. (PDF 180 KB) Additional file 3: Examination of antibody binding to Dynabeads Protein A. Beads were incubated with fluorescently labeled antibodies, washed intensively to remove excess

antibodies, and investigated by confocal immunofluorescence microscopy. Beads were incubated Fossariinae simultaneously with the antibodies indicated on the left following bead-manufacturers protocol. Dynabeads Protein A bind efficiently humanized Trastuzumab (II), while no direct binding of goat α-human Cy5 antibody occurs (III). Following pretreatment with the chimeric murine Cetuximab (IV) or Trastuzumab (not shown), the α-human antibody can be bound by the beads (IV, V). (PDF 68 KB) Additional file 4: Absence of Dynabeads Protein A internalization into 4T1-HER2 cells following incubation with goat α-human Cy5 antibody. Following fixation extracellular beads were counterstained by adding Trastuzumab-Alexa488 into the supernatant. Cells were then analyzed for bead immunofluorescence using a confocal microscope. Stacked images of 5 to 16 μm tissue height were analyzed for Cy5-positive and Alexa488-negative beads. No intracellular beads were detected, indicating the lack of intrinsic bead uptake by 4T1-HER2 cells.