The purposes of this study were to set up the method of the natural killer(NK) cell activity assay using the flow cytometer and to examine the characteristics and distribution of the NK cell during rat hepatocarcinogenesis. Forty five male 6 week-old specific pathogen free(SPF) Sprague-Dawley rats were randomly divided into three groups. Group I was the non-treated control and given normal diet and water. Group II was treated with diethylnitrosamine(DEN, 200mg/kg, i.p.) and partial hepatectomy. Group III was treated with DEN, partial hepatectomy and 0.05% phenobarbital sodium in water from 3 to 16 weeks. All animals were examined the morphology of the large granular lymphocyte(LGL), the LGL percent of the total lymphocytes and the LGL conjugation rate with YAC-1 cell in peripheral blood, spleen and liver. Moreover, activity of the LGL isolated from peripheral blood lymphocytes was determined using the flow cytometer. As results, LGL were observed in the peripheral blood, spleen and liver. LGL were observed the relatively faintly staining basophilic cytoplasm with granules, and eccentric, often kidney-shpaed nuclei in Giemsa stain. Its size was 11~13 micro meter. LGL percentage of the isolated lymphocytes in peripheral blood, spleen and liver were 1.8~2.3%, 1.3~1.4% and 0.87~0.99%, respectively. LGL conjugation rate with YAC-1 cell was shown to be peripheral blood(9.3~10.3%) spleen(7.7%~8.7%)liver(5.6~7.0%). The activity of the LGL isolated from peripheral blood lymphocytes in Group I, II and III was 33.7%, 30.5% and 35.4%, respectively. However, all values were not sighificantly between groups.

The present study was conducted to investigate the incidence of Pasteruella multocida infection in Youngnam swine herds during the period from March 1988 to Ferbruary 1989 and some properties of the isolated organisms. P multocida was isolated from 22 (43.1 %) of 51 growing pigs of 4 to 12 weeks of age and from 8 (80.0 %) of 10 herds. From nasal turbinates of 102 slaughtered pigs, 47 (46.1 %) pigs were culture positive and pigs from 8 (88.9 %) of 9 heards were found to be infected with P multocida. From lungs of 101 slaughtered pigs, 42 (41.6 %) pigs were culture positive and the pigs from 11 (91.7 %) of 12 herds were found to be infected with P multocida. The majority of biochemical and cultural propertis of the P multocida isolates were identical to those of the standard strains. The isolation frequencies of P multocida in relation to pig snout lesion grades of 0 to 5 were 28.6 %, 41.6 %, 48.0 %, 50.0 % 85.7 %, and 100 %, respectively