carinii infection in rats was established as described previously [21]. Briefly, female Sprague-Dawley rats (Harlan, Indianapolis, IN) of 120-140 g were divided into three groups designated Normal, Dex, and Dex-Pc rats. Normal rats were immunocompetent and
uninfected. Since rats must be immunosuppressed in order to develop PCP upon inoculation of Pneumocystis organisms, they were immunosuppressed by giving dexamethasone (1.8 mg/liter) continuously in drinking water to reduce the number of CD4+ T lymphocytes. These rats were referred to as Dex rats. Although the Dex rats were continuously immunosuppressed for nine weeks, they showed no signs of disease. Dex-Pc rats were Dex rats transtracheally inoculated with see more 7.5 × 106 P. carinii organisms one week after initiation of immunosuppression. To prevent other opportunistic infections, immunosuppressed rats were given 10,000 units of Selleckchem Wortmannin penicillin (Butler, Dublin, OH) weekly by intramuscular (i.m.) injection. All P. carinii-infected rats showed signs of PCP including weight loss, dark eyes, hunched posture, and respiratory distress eight weeks after inoculation of the organisms and were sacrificed for isolation of AMs. Age-matched Normal rats were used as controls, while age-matched Dex rats were
used to control for effect of the steroid treatment. Giemsa and silver staining of lung impression smears was performed to determine the existence of Pneumocystis and other microorganisms. Any lungs that contained other microorganisms were excluded. All animal studies were approved by the Indiana University Animal Care and Use Committee and supervised by veterinarians. Isolation of alveolar macrophages Rats were anesthetized
by i.m. injection of 0.1 ml ketamine mixture (80 mg/ml ketamine hydrochloride, 0.38 mg/ml atropine, and 1.76 mg/ml acepromazine) and then sacrificed. The thoracic cavity and trachea were check details exposed by dissection. Bronchoalveolar lavage fluid (BALF) was obtained by instilling 5 ml of sterile phosphate Fossariinae buffered saline (PBS) one at a time into rat lungs with a 14-gauge angiocath (BD Biosciences, Bedford, MA) and then recovered until a total of 50 ml BALF was obtained [22]. The cells in this 50-ml BALF were pelleted by centrifugation at 300 × g for 10 min and then resuspended in 5 ml of Dulbecco’s Modified Eagle Medium (DMEM). AMs were isolated by adherence on plastic tissue culture dishes at 37°C with 5% CO2 for 1 hr followed by washing with warm PBS three times to remove unattached cells. The purity of AMs was greater than 97% as determined by anti-RMA staining described previously [23]. Isolation of RNA from alveolar macrophages AMs from four each of Normal, Dex, and Dex-Pc rats were used. Total RNA was isolated individually from each sample using the RNeasy kit (Qiagen) according to manufacturer’s instructions. Approximately 2 × 106 cells from each animal were used. The cells were washed with PBS and then lysed with 350 μl of Buffer RLT in the kit.
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