Extended colostrum feeding for 2 weeks improves growth performance and reduces the susceptibility to diarrhea and pneumonia in neonatal Holstein dairy calves.

The objective of this study was to determine the effect of partial replacement of whole milk with colostrum on the growth performance and health status of Holstein dairy calves. Neonatal heifer calves (n = 144; 2 d of age; 39.3 ± 0.82 kg of body weight, BW; mean ± SE) were assigned randomly to 3 groups with partial replacement of pasteurized whole milk with pasteurized colostrum at 0 (C0; 0 kg/d of colostrum + 5 kg/d of whole milk), 350 g (C350; 0.350 kg/d of colostrum + 4.650 kg/d of whole milk), or 700 g (C700; 0.700 kg/d of colostrum + 4.300 kg/d of whole milk) for 14 d; there were no refusals of liquid feed. From d 15 onward, the calves were fed with 5 kg/d of pasteurized whole milk, weaned on d 61, and monitored until d 81 of life. Throughout the study, the calves had free access to fresh clean water and calf starter. Partial replacement of whole milk with colostrum increased liquid feed dry matter intake (DMI) but decreased milk DMI; however, intakes of starter DMI, total DMI, metabolizable energy, crude protein, and ether extract were not affected by treatments. Overall, the C700 calves recorded greater weaning weight, final BW, heart girth change, feed efficiency, and average daily gain (ADG). The calves fed milk had a higher chance of having rectal temperature ≥39.4°C and general appearance score ≥2 compared with those receiving colostrum in their milk. Diarrhea was more prevalent in C0 versus C700 calves. The occurrence of pneumonia tended to be higher in milk-fed calves compared with C350 and C700 animals. Colostrum feeding resulted in fewer days with a rectal temperature ≥39.4°C, general appearance ≥2, diarrhea, and pneumonia. We computed Cliff's delta (effect sizes) of the extended colostrum feeding (C350 vs. C0, C700 vs. C0, and C700 vs. C350) on starter and milk DMI, ADG, BW, and feed efficiency. In C350 calves, the effect sizes (Cliff's delta) for milk DMI, ADG, BW, and feed efficiency were positive and small, but negative in C700 calves. Compared with C350 treatment, C700 treatment resulted in greater final BW with moderate effect size. Positive and moderate effects of feeding colostrum (C700 vs. C0) were observed on postweaning ADG and final BW. The findings showed that the inclusion of 700 g of colostrum in 5 kg of milk may be beneficial to the growth and health of dairy calves.

Environmental risk factors for type 1 diabetes.

The incidence of type 1 diabetes has risen considerably in the past 30 years due to changes in the environment that have been only partially identified. In this Series paper, we critically discuss candidate triggers of islet autoimmunity and factors thought to promote progression from autoimmunity to overt type 1 diabetes. We revisit previously proposed hypotheses to explain the growth in the incidence of type 1 diabetes in light of current data. Finally, we suggest a unified model in which immune tolerance to ß cells can be broken by several environmental exposures that induce generation of hybrid peptides acting as neoautoantigens.

Sclerostin antibody treatment enhances bone strength but does not prevent growth retardation in young mice treated with dexamethasone.

OBJECTIVE: Exposure to supraphysiologic levels of glucocorticoid drugs is known to have detrimental effects on bone formation and linear growth. Patients with sclerosteosis lack the bone regulatory protein sclerostin, have excessive bone formation, and are typically above average in height. This study was undertaken to characterize the effects of a monoclonal antibody to sclerostin (Scl-AbI) in mice exposed to dexamethasone (DEX). METHODS: Young mice were concomitantly treated with DEX (or vehicle control) and Scl-AbI antibody (or isotype-matched control antibody [Ctrl-Ab]) in 2 independent studies. Linear growth, the volume and strength of the bones, and the levels of bone turnover markers were analyzed. RESULTS: In DEX-treated mice, Scl-AbI had no significant effect on linear growth when compared to control treatment (Ctrl-Ab). However, in mice treated with DEX and Scl-ABI, a significant increase in trabecular bone at the femoral metaphysis (bone volume/total volume +117% versus Ctrl-Ab-treated mice) and in the width and volume of the cortical bone at the femoral diaphysis (+24% and +20%, respectively, versus Ctrl-Ab-treated mice) was noted. Scl-AbI treatment also improved mechanical strength (as assessed by 4-point bending studies) at the femoral diaphysis in DEX-treated mice (maximum load +60% and ultimate strength +47% in Scl-AbI-treated mice versus Ctrl-Ab-treated mice). Elevated osteocalcin levels were not detected in DEX-treated mice that received Scl-AbI, although levels of type 5b tartrate-resistant acid phosphatase were significantly lower than those observed in mice receiving DEX and Ctrl-Ab. CONCLUSION: Scl-AbI treatment does not prevent the detrimental effects of DEX on linear growth, but the antibody does increase both cortical and trabecular bone and improves bone mechanical properties in DEX-treated mice.

Corticosteroids usage in pediatric liver transplantation: To be or not to be!

The theoretical risks of early SW, <3 months post-LT, and complete elimination (steroid-free LT) lie in mainly three areas, namely the risks of AGR, CGR, and the development of d-AIH that has been described in SW post-LT in children. These should be balanced against the benefits of early SW mainly manifested as effects on growth post-LT. In this paper, we focused on the clinical trials that included CS therapy risks and benefits in pediatric LT. Focusing mainly on CGR and d-AIH as risks, and the beneficial effects on growth post-LT with either low-dose CS, SW, or steroid-free regimens. Main conclusions from comparing a large number of studies are: early SW or elimination from immunosuppression protocols was neither harmful to the patient nor to the graft survival rate in the short term, the overall impression is that steroids negatively affect growth in LT recipients when used in high doses and prolonged course, and that development of d-AIH is not associated with CS therapy with evidence that chronic low dose steroids post-LT have no preventative role against d-AIH.

Brothers and reduction of the birth weight of later-born siblings.

It has been speculated whether maternal immune responses against male-specific minor histocompatibility (H-Y) antigens affect pregnancies negatively. This study explores, on a population level, whether previous births of boys compared with girls are associated with a decrease in birth weight of later-born siblings. The population was identified in the Danish Birth Registry and consisted of all Danish women who gave birth to their first-born singleton from 1980 to 1998. The women were followed until 2004, and their subsequent births were recorded. A total of 545,839 second- to fourth-born children were identified. The authors used linear regression to analyze the association between sex of preceding children and birth weight of subsequent siblings. Brothers compared with sisters reduced the birth weight of later-born siblings. One or two brothers, respectively, reduced the mean birth weight of later-born boys by 29 g (p = 0.0001) and 38 g (p = 0.0001) and later-born girls by 17 g (p = 0.0001) and 21 g (p = 0.0001) compared with later-born siblings with no brothers. Part of this association was due to a shorter gestation among later-born siblings with brothers. An explanation for these results could be maternal immune reactions directed against the H-Y antigens initiated during pregnancies with boys. The findings might add to the understanding of both normal and pathologic pregnancies.

Impact of elimination diets on nutrition and growth in children with multiple food allergies.

PURPOSE OF REVIEW: Growth and nutritional intake of children with cows' milk allergy and other food allergens has been thoroughly investigated in recent years across many different countries and age groups. An impaired growth in atopic children should not be attributed only to a high number of allergens and foods to be avoided, but to a general condition of 'sub-inflammation', which unfavorably affects the absorption and utilization of fuel and substrates. Atopic study participants may represent a good target for personalized nutrition and in this review we sought to outline many of the issues that should be taken into account when dietitians advise patients regarding food avoidance and expected effects on growth. RECENT FINDINGS: The dietary management of food allergy requires appropriate dietary choices to maintain adequate growth, starting with special formulas in infancy. An emerging area of research is the fussy eating related to the exclusion of cow's milk and other foods during infancy and the long-term effects on eating habits and food preferences. SUMMARY: Study participants with either mono or polyallergic diseases should ideally undergo the definition of their allergic and metabolic characteristics, to precisely adjust dietary interventions on an individual basis to support the genetic potential of growth and prevent unfavorable outcomes.

Long-term effect of early protein malnutrition on growth curve, hematological parameters and macrophage function of rats.

To evaluate the long-term effect of mild-early maternal protein malnutrition on weight gain, hematological parameters and macrophage function in rats at adult age, we compared rats whose dams were fed diets containing either 9.5% (low protein-LPD) or 23% protein (normal-NPD) for the first 12 d of lactation. At 80 d of age, the functions of spreading, phagocytosis and killing Candida albicans were determined in resident peritoneal macrophages, whereas leukocytes and red blood cells were counted in peripheral blood. The number of resident peritoneal macrophages from LPD was the same as from NPD, but the ability of spreading and phagocytosing opsonised yeast was impaired. Besides, they were not able to block the germ tube formation or kill C. albicans to the same extent as in the control group. The low protein diet produced a significant reduction in the pups' growth and in hematological parameters although no difference was found in leukocyte counts. Taken together the data suggest that protein malnutrition during early lactation induces permanent alterations in macrophage function, body composition and hematological status, which are not restored completely even after a normal protein diet is supplied.

Ontogeny of the allergic inflammatory response.

The ability to produce allergic responses begins early in fetal life along with the development of other elements of the immune system. Among the most interesting questions related to the development of allergic disease are whether the fetus in utero commonly is exposed to sufficient allergen to induce IgE production and how much the mother's immune responses affect the developing fetal immune system. After birth, it seems that many factors, including the frequency and severity of infections and the timing and intensity of allergen and animal exposures, continue to influence immune development.

Functional characterization of monoclonal antibodies specific to growth hormone receptor.

Upon engagement with appropriate ligands, receptors can be activated to initiate various metabolic and morphological changes in living cells. An attempt was made in this study to generate monoclonal antibodies (mAb) specific to recombinant rat growth hormone receptor (GHR) and subsequently to investigate their ability to act as biologically active ligands. Three mAbs, designated 1A9, 1H2 and 2C3, were produced and all were highly reactive with GHR in an enzyme-linked immunosorbent assay. In contrast to 1H2, 1A9 and 2C3 competed with radioactive growth hormone (GH) tracer for the binding to GHR in a radioreceptor assay, suggesting that the GH-binding sites of GHR were identical, or very close to its epitopes recognized by 1A9 and 2C3. The molecular interaction evaluated by the BIAcore technology further demonstrated the separate GHR epitopes for 1A9 and 2C3. 2C3 apparently targeted the precise GH-binding sites of GHR, while the antigenic determinants for 1A9 were not at the site, but adjacent to it. Functional analysis showed that 2C3 promoted the growth of hypophysectomized rats, whereas others failed to do so. Therefore, findings from the present study suggest that these mAbs recognize distinct GHR epitopes and are useful for investigating the structure-function relationship of GHR. Furthermore, 2C3 may prove important as a biologically active agonist for better understanding of the process of GHR activation relevant to growth.

Epitope mapping and analysis of a growth-enhancing monoclonal antibody by limited tryptic digestion of porcine GH.

In this study, the epitope of a murine PS-7.6 monoclonal antibody (mAb) which was raised against the recombinant porcine GH (pGH) and subsequently shown to enhance the growth-promoting activity of pGH in a hypophysectomized rat model, was mapped by the limited tryptic digestion of pGH. A pGH fragment corresponding to amino acid residues 70-95 was separated by reverse-phase HPLC and also immunoprecipitated by PS-7.6 mAb. This fragment was found in an RIA to compete with radiolabelled pGH for the binding of PS-7.6 mAb in a dose-dependent fashion. Several peptides covering this potential epitope region of pGH(70-95) were synthesized and assayed by competitive RIA. The results suggested that pGH(75-90) was the optimal sequence recognized by PS-7.6 mAb. Sequential alanine substitution of each residue of pGH(75-90) revealed that the side chains of Leu76, Ile83 and Leu87 were critical for binding to PS-7.6 mAb. Other residues could be replaced by alanine without substantially altering the binding affinity. The region of amino acids 75-95 comprises the C-terminal end of the second helix of pGH and the repeating pattern of i and i + 3 (i + 7) of the critical amino acids appears consistent with PS-7.6 mAb binding to the hydrophobic side of the helix. The sequence and the helical structure of the epitope of PS-7.6 mAb provide the basis for designing the effective peptide vaccines to enhance the growth performance of animals.

Growth hormone and insulin-like growth factor-I responses in steers actively immunized against somatostatin or growth hormone-releasing factor.

Steers were actively immunized at 81 days of age against human serum albumin (hSA; controls) or hSA conjugated to either somatostatin (SRIF) or growth hormone-releasing factor (GRF). Binding titres were observed for the respective peptide antigens after all steers had been given booster immunizations. Although no effects of treatment were observed in SRIF-immunized steers, mean serum concentrations of GH and insulin-like growth factor (IGF-I) were suppressed (P less than 0.01) in GRF-immunized steers when compared with hSA-immunized controls. Mean concentrations of prolactin did not differ with treatment but showed seasonal fluctuations (P less than 0.001) associated with changes in the daylength. In contrast to its marked effect upon serum concentrations of IGF-I, immunization against GRF resulted in a relatively small (6%) but significant decrease in body weight gain (P less than 0.01) and an increase in carcass backfat thickness (P less than 0.05). In summary, our findings have shown the susceptibility of steers to growth modulation by GRF immunoneutralization. Secondly, the poor relationship observed between serum concentrations of IGF-I and growth rates in GRF-immunized steers suggested that circulating IGF-I may not be the principle factor determining the post-weaning growth rate in cattle.

Association between steatorrhea, growth, and immunologic status in children with perinatally acquired HIV infection.

OBJECTIVE: To examine the prevalence of steatorrhea and exocrine pancreatic insufficiency (EPI) and their association with growth and immune status variables in children with perinatally acquired human immunodeficiency virus (HIV) infection. DESIGN: Cross-sectional study. SETTING: Tertiary care HIV subspecialty practice. PARTICIPANTS: Children with perinatally acquired HIV infection. Exclusion criteria included being younger than 1 year and receiving mineral oil as a medication. METHODS: Weight, height, and upper arm anthropometric variables were measured. Spot stool samples were analyzed for steatorrhea using the Sudan III qualitative test and for EPI using fecal elastase-1 enzyme assay. Hormone-stimulated pancreatic function testing and 72-hour stool and dietary fat sample collection were performed when fecal elastase-1 enzyme was in the range of EPI, defined as less than 200 microgram/g. HIV RNA viral load, CD4 status, type of antiretroviral therapy, and biochemical evidence of hepatobiliary disease were measured within 3 months of stool sample collection. z Scores were computed for height, weight, triceps skinfold, and upper arm muscle area. RESULTS: We enrolled 44 patients (23 girls [52%]) with a mean +/- SD age of 7.4 +/- 3.1 years. None had hepatobiliary disease. The prevalence of steatorrhea was 39% (95% confidence interval, 23%-56%). The prevalence of EPI was 0% (95% confidence interval, 0%-9%). There were no associations between steatorrhea and EPI, growth, HIV RNA viral load, CD4 status, or type of antiretroviral therapy. Older children had decreased z scores for height (r = -0.42; P =.006). CONCLUSIONS: The clinical significance of steatorrhea in children with HIV infection is unclear. Furthermore, its evaluation should focus on nonpancreas-based conditions. Continual close monitoring of growth is essential in children with HIV infection.

Growth hormone administration can improve growth in glucocorticoid-injected rats without affecting the lymphocytopenic effect of the glucocorticoid.

Long-term glucocorticoid therapy as it is found in children with kidney transplants results in retarded longitudinal growth. The aim of the present study was to evaluate if growth hormone could improve longitudinal growth in glucocorticoid-injected experimental animals without affecting the immuno-suppressive effect of the glucocorticoid. 117 female Wistar rats were injected from the ages of 2-5 months with either saline, growth hormone (5 mg/kg/day), or glucocorticoid (methylprednisolone 1,3,6 or 9 mg/kg/day), alone or in combination with growth hormone (5 mg/kg/day). Body weight, nose-tail length and length of the lower extremity were measured continuously during the study. After death, femoral and tibial lengths, growth at the proximal, epiphyseal growth plate, muscle mass and immunological parameters were examined. Glucocorticoid administration dose-dependently decreased weight gain and growth (nose-tail length, growth of the lower extremity), lengths of femur and tibia, growth at the proximal, epiphyseal growth plate and muscle mass. Glucocorticoid administration decreased spleen and thymus weight as well as the white blood cell count (WBC count), mainly due to a decrease in lymphocyte number. For all glucocorticoid doses examined, growth hormone increased weight gain and growth (nose-tail length, growth of the lower extremity), lengths of femur and tibia, and muscle mass. The effects of growth hormone were, however, dose-dependently decreased by glucocorticoid administration. Growth hormone injection alone increased the WBC count due to an increase in the number of lymphocytes and monocytes. When the two hormones were administered concomitantly, growth hormone did not, however, reverse the lymphocytopenic effect induced by glucocorticoid administration. In conclusion, growth hormone can increase longitudinal growth and increase muscle mass in glucocorticoid-injected rats, if a glucocorticoid preparation of a short half-life is used. Growth hormone does not reverse the lymphocytopenic effect of glucocorticoid injections.

Clinical aspects of coeliac disease in children with insulin-dependent diabetes mellitus.

Coeliac disease (CD) is heterogeneous in its clinical presentation and pathological expression. Silent, latent and potential forms represent the submerged part of the so-called "coeliac iceberg". The association of insulin-dependent diabetes mellitus (IDDM) and CD has been widely reported. For the screening of CD in diabetic patients, anti-reticulin R1 (ARA-R1) and anti-endomysium (AEA) antibodies are more reliable markers than anti-gliadin (AGA) antibodies. Recent studies have reported an increased prevalence of CD in children with IDDM. In our experience intestinal biopsy confirmed a diagnosis of CD in 6 out of 172 diabetic patients, with a prevalence of 3.5%. Only occasionally does CD precede the onset of IDDM; more often CD is diagnosed shortly or sometimes years after the onset of diabetes. Typical gastrointestinal complaints of CD (such as diarrhoea, abdominal distension) are rare in IDDM patients, while atypical isolated signs or symptoms of CD are more common, in particular sideropenic anemia, short stature, delayed puberty, epilepsy, hypertransaminasemia, dyspeptic symptoms, herpetiform dermatitis, and recurrent aphthous stomatitis. It is recommended that all diabetic children, even those asymptomatic, should be screened yearly for CD, using a combination of AGA plus ARA-R1 and AEA.

Effects of early immune stress and changes in dietary metabolizable energy on the development of newly hatched turkeys. 1. Growth and nutrient utilization.

Two experiments were conducted to document the effects of an early immunologic stress and changes in dietary ME(n) on growth and nutrient utilization of newly hatched turkeys. Treatments in both experiments consisted of a complete factorial arrangement of two types of injection and four isonitrogenous diets. Turkeys were injected i.p. with saline (SAL) or a solution of lipopolysaccharide (LPS) (100 micrograms LPS/mL SAL) at 1, 3, and 5 d of age. In Experiment 1, two diets were formulated to contain 2,800 kcal ME(n)/kg. One was a corn-soybean meal-based diet (CSBM) and the other contained 8% Solkafloc (SKF). A third diet (3,100 kcal ME(n)/kg) was formulated by substituting 8% sucrose (SUC) for the 8% SKF. The fourth diet included in Experiment 1 was formulated to contain 3,700 kcal ME(n)/kg. The CSBM and SUC diets were also included in Experiment 2. Two additional diets tested in Experiment 2 were the CSBM diet containing 74.5 mg ibuprofen/kg (IBU) and a corn-soybean meal-based diet with a ME(n) value of 3,100 kcal/kg (CS31). Injection with LPS reduced (P < .05) BW of turkeys throughout Experiment 1 and until 9 d of age in Experiment 2, as compared with injection with SAL, irrespective of dietary treatment. The reduction in BW was mainly due to a decrease in feed intake (FI) (P < .05). Turkeys fed diets with 3,100 kcal ME(n)/kg were heavier (P < .05) than those fed diets with 2,800 kcal ME(n)/kg, irrespective of injection. Inclusion of ibuprofen to the CSBM diet from 1 to 14 d improved (P < .05) BW and feed efficiency (P < .01) of turkeys at 14 d of age, compared with turkeys fed the CSBM diet. Determined ME(n) was not affected by LPS injection. Adverse effects of LPS injection on growth of turkey poults were mainly the consequence of a reduced FI and not of altered nutrient utilization. These effects were not fully alleviated by feeding a diet with 3,100 kcal ME(n)/kg.

Phenotypic selection for residual feed intake and its effect on humoral immune responses in growing layer hens.

According to the resource allocation theory, animals have to make a trade-off between resource-demanding life traits to obtain maximal fitness. Artificial selection toward efficient producing farm animals, however, may have created animals that have an impaired ability to divert resources to maintenance processes, such as responding to immune challenges. Residual feed intake (RFI), defined as the difference between observed feed intake (FI) and expected feed intake based on metabolic BW and growth, was used as a measure for feed efficiency. Individual BW and FI of 352 pullets were recorded weekly from 4 until 14 wk of age to estimate RFI. The top 50 efficient R- and the top 50 nonefficient R+ birds were selected. BW and BW gain in both groups were similar. FI and RFI, however, were significantly higher in R+ birds. Thirty animals out of every group were randomly allocated to 1 of 3 treatments: immunization with keyhole limpet hemocyanin (KLH), Mycobacterium butyricum, or heat-inactivated Salmonella enteritidis bacteria. Antibody titers against KLH, M. butyricum, or Salmonella lipopolysaccharide did not differ between R+ and R- birds. The antibody titer against Salmonella protein was higher in R+ birds. We concluded that a population of chickens from a commercial breed shows considerable variation in RFI. Specific antibody production against KLH, M. butyricum, and S. enteritidis lipopolysaccharide, however, is not influenced by efficiency in terms of RFI. R+ animals may have a higher level of nonantigen specific antibodies, as indicated by the higher antibody response to Salmonella protein.

Effects of early immune stress and changes in dietary metabolizable energy on the development of newly hatched turkeys. 2. Selected characteristics of immune function.

Two 21-d experiments were conducted to document the effects of an early immunologic stress and changes in dietary ME(n) on selected characteristics of immune function of newly hatched turkeys. Eight treatments were included in each experiment. Treatments were the result of complete factorial arrangements of two types of injection and four isonitrogenous diets. Turkeys in both experiments were injected i.p. with .5, .5, and .2 mL of saline (SAL) or .5, .5, and .2 mL of a solution of Escherichia coli lipopolysaccharide (LPS) (100 micrograms LPS/mL SAL) at 1, 3, and 5 d of age, respectively. In Experiment 1, two diets were formulated to contain 2,800 kcal ME(n)/kg. One was a corn-soybean meal based diet (CSBM) and the other contained 8% Solkafloc (SKF). A third diet (3,100 kcal ME(n)/kg) was formulated by substituting 8% sucrose (SUC) for the 8% SKF. The fourth diet (HE) included in Experiment 1 was formulated to contain 3,700 kcal ME(n)/kg. The CSBM and SUC diets and two additional diets were tested in Experiment 2. The latter were the CSBM diet containing 74.5 mg ibuprofen/kg (IBU) and a corn-soybean meal diet formulated to contain 3,100 kcal ME(n)/kg (CS31). Concentrations of plasma IgG and jejunal IgG and IgA were not affected by injection or diet. Age-related changes in Ig concentrations were consistently observed in Experiments 1 and 2. Injection with LPS reduced the number or responses of blood leukocytes to mitogens at 8 d of age (P < .01), as compared with samples from turkeys injected with SAL. Leukocytes in whole blood samples from turkeys fed the HE diet responded less to LPS stimulation than those fed the SUC diet (P < .01). Injection with LPS did not markedly affect the characteristics of immune function studied, and feeding a diet with 3,100 kcal ME(n)/kg and 28.5% crude protein did not measurably affect the characteristics of immune function of young turkeys.

Neural cell adhesion molecules.

Adhesion molecules are expressed on the surface of various cells and establish cell-cell interaction, playing important roles in development, inflammatory reaction, immune response, and tissue regeneration. Neural adhesion molecules, found on neurons or glial surfaces, are involved in the migration of neurons, neurite formation, myelination, and denervation--reinnervation. The roles of cell adhesion molecules in malignancies, normal and abnormal development and as receptors in viral infections, constitute major fields of research and may have important diagnostic and therapeutic implications.

Immunological approaches for manipulation of animal growth, body composition and fecundity.

The ability to manipulate certain physiological processes by using the immune system, so as to regulate endocrine secretions and/or actions is clearly possible. The dramatic effects of immunocastration and the ability to increase ovulation rates in sheep are probably the best examples. Other approaches along similar lines have produced equivocal results, the effects of immunization against somatostatin being the most notable case. Although anti-idiotypic antibody approaches to producing hormone mimics have also been shown to be attainable and, indeed, possibly involved in certain auto-immune dysfunctions of the endocrine system, to date no successful applications of this approach have been demonstrated in commercial livestock. The ability to enhance hormone action using antibodies is an extremely promising area. Its prospects probably hinge on the ability to synthesize suitable short peptides which will mimic epitopes on the hormone and so permit the development of active immunization techniques to produce polyclonal antibodies of restricted and enhancing specificity. It seems less likely that administration of hormones pre-complexed to monoclonal antibodies has any potential as a practical approach to manipulating animal productivity. All of these approaches involving active immunization suffer the same limitations: the highly variable response of individual animals and the general inability to regulate the duration of the response; a need to find suitable adjuvants to replace the almost universally used and commercially unacceptable Freund's adjuvant; and the problem of trying to generate what, in most cases, is an auto-immune response. A second group of approaches consists of attempts to use antibodies in their classical role, that is by targeting antigens or cells for destruction by the immune system. These include, for example, antibodies directed against adipose tissue or cytotoxic antibodies to specific hormones aimed at destruction of the hormone-secreting cells. Since these are passive immunization techniques, the antibodies can be assessed carefully in vitro and administered in appropriate doses. However, success in these applications is largely dependent on the inability of damaged tissues to regenerate, since retreatment is generally precluded because of the anti-immunoglobulin response induced in treated animals. Toleragenic forms of such antibodies or the use of appropriate immunosuppressants may ultimately remove this limitation. Perhaps the greatest current limitation to the use of all of these techniques in animal production systems, however, is public resistance to the use of such techniques.(ABSTRACT TRUNCATED AT 400 WORDS)

[Erythroblast antigen expression in murine hematopoietic and nonhematopoietic cells. 2. An immunofluorescent study in pre- and postnatal ontogeny using monoclonal antibodies]. / Ekspressiia antigena éritroblastov v krovetvornykh i nekrovetvornykh kletkakh myshi. 2. Immunofluorestsentnoe issledovanie v pre- i postnatal'nom ontogeneze s pomoshch'iu monoklonal'nykh antitel.

The expression of erythroblast antigen (Ag-Eb) in cell membranes during pre- and postnatal mouse development was studied by immunofluorescence using the monoclonal antibody MAE-15. Ag-Eb was detected in embryonic liver, spleen, epithelia of intestine, various glands and skin, as well as in extraembryonic tissues (yolk sac and trophoblast). In pregnant mice positive immunofluorescence was observed in placenta and on the surface of decidual cells in uterus. In adult non-pregnant mice Ag-Eb expression was detected not only in membranes of erythroid cells, but also in non-hemopoietic tissues, such as epithelia of various glands, intestine, kidney and testis, brain endothelium, basal layer of epidermis, and intercalated discs of the heart muscle. A possible role of Ag-Eb in processes of cell transport is discussed.