Observation of lymphocyte function in perinatal cows and neonatal calves.

The changes in lymphocyte transformation rate and proportion of E-rosette forming cells (ERFC), in addition with serum concentration Qf IgG and certisol were examined on dairy cows in the perinatal period. The cows were bled at the various stages of pregnancy, parturition and post-parturient period. Also in calves, the lymphocyte transformation rate and proportion of ERFC were examined on the blood sarnples collected at weekly interval from birth to 5 weeks of age, The blastogenic response of lymphocytes to concanavalin A and pokeweed rnitogen decreased beginning from the 3rd trimester and reached a minimum at parturition. The proportion of ERFC and serum IgG concentration also decreased with parturition. The high serum cortisol level at parturition may infiuerice lymphocyte activity in cows. In neonatal calves, the number of ERFC and responsiveness of peripheral lymphocytes to mitogen corresponded to adult level immediately after birth.-KEy woRDs: blastogenesis, E-rosette formation, perinatal immunity --JPn, J. Vet. Sci. 49(3): 469-475, t9g7 It is well known that the incidence of bovine infectious diseases uch as mastitis or peurperal infections is high during the perinatal period. Thetefbre, the immune competence of cows has been supposed to be depressed by the stress of pregnancy and partuntion, There are some reports dealing with the function of bovine perlpheral lymphocytes in the perinatal period [13, 21, 22]. Well et al, [22] reported a reduced 3H-TdR uptake in PHA-stimulated lymphocytes from newly calved cows. Kashiwazaki et aL [13] found a marked decrease of incorporation of 3H-TdR in lymphocytes from multiparous cows after calving. On the other hand, neonatal calves are often diseased with diarrhea and pneumonia particulary on large suckling farms, They have also been studied on the immune responsiveness [10, 15, 20] or on the cellular immunity {1, 12, 16, 18]. Person et aL [18] studied the sensitivity of peripheral bovine lymphocytes obtained from newborn calves up to 3 months of age and demonstrated that blastogenic responses were comparable te that of lymphocytes from adult cows although the variation was wide. The proPortion of peripheral T lymphocytes in neonatal calves is reported to be low, in general [1, 16]. However, there is also a report mentioning a considerable number of peripheral T lymphocytes in neonatal calves [12]. According to these previous studies, the immune responses of peripheraHymphocytes in perinatal cows and newborn calves were not fully discussed. In this experiment, the functiori of peripheral lymphocytes was examined in perinatal cows and calves. The number of circulating T lymphocytes, their blastogenic activity and in addition, serum IgG and cortisol levels were measured in pregnant and post-parturient cows. MATERIALS AND METHODS i Blood samples: Fifty-two Holstein cows from 2 to 10 years of age and 9 calves from the University £arm were used for this study, Blood was collected from the cows at various stages of the gestational and postJapanese Society of Veterinary Science NII-Electronic Library Service apaneseSociety fVeterinary cience