Alteration of cell-mediated immunity to Listeria monocytogenes in protein-malnourished mice treated with thymosin fraction V

Involution of thymic epithelium and low serum thymulin bioactivity in weanling mice subjected to severe food intake restriction or severe protein deficiency

The volume of epithelium in the cortex and in the medulla of the thymus was compared in four groups of weanling male and female CBA/J mice. Well-nourished controls (C), food intake restricted (R), and animals given a low-protein diet ad libitum (LP) were fed from 23 to 37 days of age. Baseline controls (B) were studied at 23 days of age. Epithelial volume fraction was estimated for each group by point-counting morphometry on electron micrographs. Other mice were used to obtain group mean estimates of thymic index (mg/g live weight) and volume fraction of cortex and medulla (light microscope-level point-counting morphometry). Cortical and medullary epithelial volumes were calculated for each animal examined by electron microscopy by obtaining the live weight and applying, in sequence, the group mean thymic index, an assumed thymic density of 1.0 mm3/mg, the group mean cortical or medullary volume fraction, and the measured cortical or medullary volume fraction for that animal. Serum thymulin bioactivity was also measured in C, R, and LP mice. The results reveal thymic epithelial involution in the two most common rodent models of malnutrition, and suggest that this may contribute to the low serum thymulin levels found in malnourished experimental animals and humans.

Thymosin fraction 5: effects on T cell functions in mice immunosuppressed by severe dietary protein deficiency

The present studies were performed to determine the effects of severe protein deficiency and subsequent injection of thymosin fraction 5 (TF5) on T and B cell functions. BALB/c mice, 4 weeks old, were fed a normal protein (21%), a low protein (4%) or a protein free (0%) diet and then injected with TF5 or buffer (PBS). A significant increase was observed in the PHA (phytohemagglutinin) and LPS (lipopolysaccharide) induced mitogenesis with increasing age of the well-nourished, PBS injected animals. The severely protein malnourished mice, PBS injected and the well nourished mice, injected with TF5 had smaller increases in both B and T cell mitogenesis with increasing age. TF5 injection of the malnourished mice increased PHA and LPS mitogenesis nearly to the levels of the well-nourished mice. The protein malnourished mice consistently had higher serum corticosteroid levels than controls. No changes in serum corticosteroids were observed with TF5 injection of controls, but there was a significant decrease in the corticosteroid levels of the severely malnourished with TF5 injection. Cytoxicity assays of T cell function, antibody dependent cellular cytoxicity and cytoxicity to mouse thymona tumor cells, in mice fed moderately protein deficient diets showed suppression compared to controls fed 20% protein. TF5 injection partially and temporarily increased these functions in the malnourished mice.

Influences of nutrition on immunity and susceptibility to mouse hepatitis virus type 2

Resistance to mouse hepatitis virus (MHV) in C3H mice is a genetic trait which appears 3-4 weeks after birth. However, when these animals were weaned on a low protein diet (8% casein), they remained susceptible to MHV-2 infection until they reached 8-9 weeks of age. During this period, the protein-restricted C3H mice were as susceptible to MHV-2 as the genetically susceptible congenic C3Hss strain. The delay in the emergence of resistance in the protein-restricted mice could be corrected by injecting these animals with spleen cells from 6-week-old C3H mice. Thymocytes from normal C3H mice, and splenocytes and thymocytes from protein-restricted C3H mice, were not protective. However, spleen cells from the protein-restricted mice were more responsive to phytohaemagglutinin, lipopolysaccharide and concanavalin A than spleen cells from normal C3H. The enhanced lymphoproliferative response in spleen cells from protein-restricted mice was abrogated by the addition of plastic-adherent cells obtained from normal C3H spleens. Spleen cells from protein-restricted and from genetically susceptible C3Hss mice also possessed more spontaneous cytotoxicity against MHV-infected 3T3 fibroblasts.

Resistance and susceptibility to infection in inbred murine strains. III. Effect of thymosin on cellular immune responses of alloxan diabetic mice

Three parameters of cell-mediated immunity, namely, (a) resistance to infection with Candida albicans, (b) in vivo release of migration inhibitory factor (MIF) into the circulation and (c) delayed hypersensitivity were markedly reduced when mice of such normally resistant high responder strains as C57B1/10SNJ and C57B1/KsJ became hyperglycaemic after treatment with alloxan. When the alloxan diabetic mice were inoculated daily intraperitoneally with thymosin fraction 5, beginning 3 days before infection, resistance to infection was greatly enhanced. When the mice were administered 5 micrograms thymosin fraction 5 for 3 days before sensitization and for 3 days before challenge, the amount of MIF released in vivo into the circulation after the antigenic challenge was much greater. When the mice were treated daily with 5 micrograms thymosin fraction 5, beginning on the day of sensitization, the capacity to develop delayed footpad reactions was increased. Thus, the treatment of alloxan diabetic mice with thymosin fraction 5 enhanced the three parameters of cell-mediated immunity that were under investigation.

Thymosin alpha 11: a peptide related to thymosin alpha 1 isolated from calf thymosin fraction 5

Two peptides related to thymosin alpha 1 have been isolated from preparations of calf thymosin fraction 5. One, lacking four amino acid residues at the COOH terminus, is designated des-(25-28)-thymosin alpha 1. The other, named thymosin alpha 11, contains seven additional amino acid residues at the COOH terminus. The sequence of this peptide is: AcSer-Asp-Ala-Ala-Val-Asp-Thr-Ser-Ser-Glu-Ile-Thr-Thr-Lys-Asp-Leu- Lys-Glu-Lys- Lys-Glu-Val-Val-Glu-Glu-Ala-Glu-Asn-Gly-Arg-Glu-Ala-Pro-Ala-AsnOH. Thymosin alpha 11, in doses of less than 300 ng per mouse, protects susceptible inbred murine strains against opportunistic infections with Candida albicans. It is approximately equal to 30 times as potent as thymosin fraction 5 and approximately equal in potency to thymosin alpha 1.

Resistance to bacterial and parasitic infections in the nutritionally compromised host

Over the past few years the relationships and interactions of diet, disease, and immunology are becoming better defined with the development and understanding of host defenses. Nutritional state, immunity, and disease all influence each other in the hospitalized patient, the elderly, and the young. Disease can alter nutritional needs and immune responses to antigens. The roles of both dietary excesses and deficiencies on cellular, secretory, and humoral immune responses are related to diseases and disease incidence in humans and experimental animals. Malnutrition alters incidence and severity of fungal, bacterial, viral, and parasitic pathogens. The mechanisms of altered disease resistance in nutritionally stressed animal models occurs via changes in the lymphoreticular endothelial system. The effects of common nutritional deficiencies, low protein, and low carbohydrate diets on antibody production, macrophage function, secretory IgA synthesis, and T-cell functions. Nutritional supplementation can increase lymphocyte function and decrease growth of some pathogens and tumors. Alternatively, obesity and high fat have roles in infectious disease and immunity.