Jl. Burton et al., IMMUNOMODULATORY ACTIVITY OF BLOOD-SERUM FROM CHROMIUM-SUPPLEMENTED PERIPARTURIENT DAIRY-COWS, Veterinary immunology and immunopathology, 49(1-2), 1995, pp. 29-38
Our previous research showed enhanced immune responses, including mito
gen-induced blastogenesis of peripheral blood mononuclear cells from f
eedlot calves and periparturient dairy cows supplemented with dietary
chromium (Cr). The objectives of the present study were to test whethe
r blood sera from Cr-supplemented periparturient cows contained immuno
modulatory activity for mitogen-stimulated peripheral blood mononuclea
r cells and, if so, to determine if this activity was explicable by di
fferences in blood profiles of some glucose-regulating hormones (insul
in, cortisol, growth hormone, insulin-like growth factor I, and tumor
necrosis factor-ct) between Cr-supplemented and unsupplemented (contro
l) animals. Blood sera from ten unsupplemented cows and nine Cr-supple
mented cows (0.5 ppm day(-1)) were collected weekly from 2 weeks befor
e to 6 weeks after parturition, and were used to supplement (1, 10, an
d 20% vol/vol) culture medium supporting concanavalin A (Con A) stimul
ated mononuclear cells enriched from blood of four nulliparous donor c
ows. Hormone concentrations were determined using radioimmunoassays. C
on A-induced blastogenesis was enhanced when 1, 10, and 20% sera from
Cr-supplemented cows was added to the mononuclear cell cultures, and t
his was particularly evident around parturition. Conversely, peripartu
m sera from unsupplemented cows depressed Con A-induced blastogenesis.
Except for a marginal rise in blood cortisol 2-4 weeks after parturit
ion, no significant effects of Cr supplementation on other hormones (i
nsulin, growth hormone, insulin-like growth factor I, tumor necrosis f
actor-alpha) were observed. These observations suggest that factors in
peripheral blood serum from Cr-supplemented cows, other than absolute
concentrations of the glucose-regulating hormones studied, modulate C
on A-induced blastogenesis of mononuclear leukocytes.