J. Schwager et J. Schulze, MATURATION OF THE MITOGEN RESPONSIVENESS, AND IL2 AND IL6 PRODUCTION BY NEONATAL SWINE LEUKOCYTES, Veterinary immunology and immunopathology, 57(1-2), 1997, pp. 105-119
The maturation of the immune system of neonatal piglets was studied by
following changes in the phenotypic composition and function of blood
-borne leukocytes. The proportion of mature T and B lymphocytes decrea
sed in the first week of birth and the circulating cells had poorly de
veloped capacities to respond to mitogens and to secrete interleukins.
From the end of the first week, however, there was a steady increase
in the proportion of mature T cells (CD4+ and CD8+) and B cells in blo
od until 6-7 weeks after birth, when the study was ended. By 3-4 weeks
, the relative proportions of different lymphocyte subsets resembled a
n adult-type composition. As they increased in prevalence, lymphocytes
also developed capacities to proliferate and secrete interleukins. Pr
oliferative responses to T-cell and B-cell mitogens reached adult leve
ls within 2 weeks and 4-5 weeks, respectively. Blood leukocytes produc
ed large quantities of IL6 by 1-2 weeks after birth and IL2 by 2-3 wee
ks. In contrast to lymphocyte patterns, the myeloid and granulocyte li
neages were dominant at birth but then declined steadily. Unlike lymph
ocytes, the monocytes, macrophages and granulocytes appeared to be ful
ly functional from the time of birth and exhibited a strong oxidative
burst after appropriate stimulations. The magnitude of this response r
emained constant over the first 6-7 weeks. These results indicate that
the first 3-4 weeks of post-natal life are a particularly susceptible
interval for newborn piglets because constitutive and functional comp
onents necessary for specific cellular immune responses remain immatur
e. This deficit may be offset by non-specific cellular mechanisms and
maternally derived antibodies. (C) 1997 Published by Elsevier Science
B.V.