Objective—To evaluate effects of colostral cells on
the ability of neonatal leukocytes to respond in a
mixed leukocyte response (MLR) as a means of evaluating
specific immune responsiveness.
Animals—10 Holstein calves, their respective dams,
and 10 unrelated adult Holstein cows.
Procedure—Soon after birth, their calves were fed
maternal whole colostrum or colostrum after cells
were removed by centrifugation. Responses for
leukocytes obtained from calves during the first 5
weeks after birth, their dams, and unrelated cows
were measured by use of 1-way MLR as an indicator
of immune development. An internal control treatment,
proliferation of lymphocytes stimulated with
Staphylococcus enterotoxin B (SEB), was also measured.
Results—Transfer of colostral leukocytes had a significant
effect on the MLR and SEB-induced response in
calves. Calves receiving whole colostrum had
enhanced responses to maternal and unrelated leukocytes
24 hours after ingestion of colostrum. These
responses decreased quickly, indicating direct modulation
of the neonatal immune response. Calves receiving
whole colostrum effectively stimulated the MLR by
24 hours after ingestion of colostrum. In contrast,
calves receiving acellular colostrum did not effectively
stimulate the MLR until 2 to 3 weeks after birth.
Conclusions and Clinical Relevance—Ingestion of
maternal colostral leukocytes immediately after birth
stimulates development of the neonatal immune system.
These maternal leukocytes enhance development
of antigen-presenting capacity as indicated by
their ability to stimulate the MLR and SEB response.
The influence of ingested maternal cells on neonatal
immunity was also indicated by a reduction in reactivity
of neonatal cells to maternal alloantigens. (Am J
Vet Res 2005;66:1854–1860)
Objective—To evaluate the effects of topical antifungal drugs and delivery vehicles on the morphology and proliferation rate of cultured equine keratocytes.
Study Population—16 corneas obtained from 8 apparently ophthalmologically normal horses < 0.5 hours after euthanasia for reasons unrelated to the study.
Procedures—Primary cultures of equine keratocytes were obtained from corneal stroma and were exposed to several concentrations of 3 commonly used, topically applied antifungals: natamycin, itraconazole, and miconazole. In addition, effects of drug delivery vehicles DMSO, benzalkonium chloride, and carboxymethylcellulose and a combination vehicle composed of polyethylene glycol, methylparaben, and propylparaben were also evaluated. Morphological changes and cellular proliferation were assessed 24, 48, and 72 hours after application.
Results—At the highest concentrations tested, all antifungals caused marked cellular morphological changes and inhibited proliferation. At low concentrations, natamycin and miconazole induced rounding, shrinking, and detaching of the cells with inhibition of cellular proliferation. Natamycin caused the most severe cellular changes. Itraconazole, at the low concentrations, caused minimal morphological changes and had a minimal effect on proliferation. All vehicles tested had significantly less effects on cellular morphology and proliferation when compared with the antifungals, except for the combination vehicle, which caused severe morphological changes and inhibited proliferation, even at low concentrations. The DMSO had minimal effects on cellular morphology and proliferation, even at high concentrations.
Conclusions and Clinical Relevance—Itraconazole had significantly less cytotoxic effects on equine keratocytes in culture than did natamycin or miconazole. Natamycin had severe cytotoxic effects in vitro.
Objective—To assess the effect of maternal cells or cellular components on neonatal immune responses to intracellular pathogens in calves.
Animals—15 Holstein calves.
Procedures—Calves were fed whole colostrum, frozen colostrum, or cell-free colostrum within 4 hours after birth. Leukocytes were obtained from calves before feeding colostrum and 1, 2, 7, 14, 21, and 28 days after ingestion. Proliferative responses against bovine viral diarrhea virus (BVDV) and mycobacterial purified protein derivatives were evaluated. Dams received a vaccine containing inactivated BVDV, but were not vaccinated against mycobacterial antigens.
Results—All calves had essentially no IgG in circulation at birth, but comparable and substantial concentrations by day 1. Calves that received whole colostrum had enhanced responses to BVDV antigen 1 and 2 days after ingestion of colostrum. In contrast, calves that received frozen colostrum or cell-free colostrum did not respond to BVDV. No differences were identified among the 3 groups in response to mycobacterial antigens.
Conclusions and Clinical Relevance—Results indicated that transfer of live maternal cells from colostrum to neonatal calves enhanced responses to antigens against which the dams had previously responded (BVDV), but not to antigens to which the dams were naïve (mycobacterial purified protein derivatives). Results suggested that cell-mediated immune transfer to neonates can be enhanced by maternal vaccination.