excerpt
Figure 1. Micrographs revealing
attachment to and invasion of
lymphocytes by Borrelia burgdorferi.
Cultured SKW 6.4 cells and
primary human peripheral B cells
were coincubated with virulent or
attenuated B. burgdorferi for 1
hour; the mixtures were then prepared
for and examined by light or
electron microscopy. The micrographs
are representative of each
susceptible host cell population.
a:
Light microscopy revealed attachment
of spirochetal tips to SKW 6.4
cells; attached spirochetes remained
highly motile yet anchored
to host cells.
b: Scanning electron
microscopy revealed that adherent
spirochetes penetrated lymphocytes
through endocytotic pits;
penetrated lymphocytes exhibited
a noticeable loss of filopodia
and other surface projections.
c:
Transmission electron microscopy
showed that intracellular spirochetes
were retained within vacuoles;
no fusion of lysosomes to endocytotic
vacuoles was observed.
d: Continued coincubation with
virulent spirochetes resulted in numerous
lymphocytes with disrupted
cell membranes. e: No such
cytopathic changes were observed
with uninfected control lymphocytes.
No such cytopathic changes
were observed with lymphocytes
incubated with Borrelia hermsii or
attenuated B. burgdorferi (not
shown). Bars Å 1 mm.
