C. Chong-cerrillo et al., Immunohistochemical analysis of Lyme disease in the skin of naive and infection-immune rabbits following challenge, INFEC IMMUN, 69(6), 2001, pp. 4094-4102
In this study, skin histopathology from naive and infection-derived immune
rabbits was compared following intradermal challenge using Borrelia burgdor
feri B31 strain. The presence or absence of spirochetes in relationship to
host cellular immune responses was determined from the time of intradermal
inoculation to the time of erythema migrans (EM) development (similar to7 d
ays in naive rabbits) and through development of challenge immunity (simila
r to5 months in naive rabbits). Skin biopsies were obtained and analyzed fo
r the presence of spirochetes, B cells, T cells, polymorphonuclear cells (P
MNs), and macrophages by immunohistochemical techniques. In infected naive
animals, morphologically identifiable spirochetes were detected at 2 h and
up to 3 weeks postinfection, At 12 and 24 h postinfection there was a marke
d PMN response that decreased by 36 to 48 h; by 72 h the PMNs were replaced
by a few infiltrating macrophages, At the time of EM development and 14 da
ys postinfection, the PMNs and macrophages were replaced by a lymphocytic i
nfiltrate, There was a greater number of spirochetes at 14 days, a time whe
n EM had resolved, than at 7 days postinfection. By 3 weeks postinfection t
here were few organisms and lymphocytes detectable. In contrast to infected
naive rabbits, intact spirochetes were never visualized in skin biopsies f
rom infection-immune rabbits; only spirochetal antigen was detected at 2, 1
2, and 24 h in the presence of a numerous PMN infiltrate. By 36 h postchall
enge, spirochetal antigen could not be detected and the PMN response was re
placed by a few infiltrating macrophages. By 72 h postchallenge, PMNs and m
acrophages were absent from the skin; B and T cells were never detected at
any time point in skin from infection-immune rabbits,The destruction of spi
rochetes in immune animals in the presence of PMNs and in the absence of a
lymphocytic infiltrate suggests that infection-derived immunity is antibody
mediated.