Immunohistochemical characterization and quantification of lymphocytes infiltrating lungs during east coast fever.
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Date
2002
Authors
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Journal ISSN
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Publisher
Sokoine University of Agriculture
Abstract
A study was conducted to investigate the hypothesis that the lungs in East Coast
fever are infiltrated by different subsets of lymphocytes that may be responsible in
the pathogenesis of pulmonary edema. Four steers 7-10 months old were
experimentally infected by subcutaneous injection with 0.5 ml of live Theileria parva
sporozoites (Muguga stabilate 3087). Two others remained as uninfected controls.
All six animals were clinically monitored daily before and after infection by
screening peripheral blood smears, lymph node smears, rectal temperatures, lymph
node enlargement, coughing and dyspnea. Also blood samples were taken at
intervals of 3-4 days and analysed for total RBC and WBC counts, Hb, PCV and
exsanguinated to death under general anaesthesia at the onset of dyspnea,
together with one of the controls for sampling of lung tissues. In addition, two lung
tissue samples were collected from two ECF naturally infected cattie that were
slaughtered during the advanced stage of the disease. The lung tissue samples
from the experimentally and naturally infected animals were fixed in 4% neutralbuffered
formaldehyde (pH 7.4) for 48 hours and subjected to routine tissue
processing procedures to obtain 4 gm thin sections that were stained routinely by H
& E for histopathological examination and immunohistochemically by monoclonal
antibodies labelled by streptavidin-biotin peroxidase complex to visualize
lymphocyte subsets BoCD21+, BoCD4+, BoCD8+ and BoWCl+. Rectal temperatures
differential leukocyte count. Each of the infected animal was humanely started to increase above normal by day 8 post infection while ECF was confirmed
by lymph node smear examination by day 7 and dyspnea by day 15 post infection.
It was demonstrated that the majority of lymphocyte subsets infiltrating the lungs
of cattle infected with Theileria parva are BoCD4+ and BoCD8+ in the acute and
advanced stages of ECF, respectively. The BoCD8+ T cells were about eleven times
more than the rest of the other subsets in the naturally infected animals
slaughtered in the advanced stages of ECF. The apparent higher mean number of
both BoCD21+ and BoWCl+ during midway of the course of infection suggests that
these may have more roles to play in this stage than in the advanced stages of
Theileria parva infection. Notwithstanding the mechanisms that attract these
lymphocytes into the lungs, their presence indicates that they likely bring about
local release of cytokines that contribute towards development of inflammation and
pulmonary edema. It was concluded that any endeavour to develop ways to treat
Theileria parva infection should study the specific cytokines released during ECF
Description
Dissertation
Keywords
Immunohistochemical, Immunohistochemical, Lungs, Pulmonary edema