Immunity is a task that demands a lot of energy from the body and which can be altered by psychological stress, strenuous exercise, growth, reproduction or even some metabolic disorders.
Immunity can be divided into two big categories:
- Innate immunity, called as such because it is immediate and doesn’t require a learning process. In effect, the cells that intervene possess mechanisms able to recognise pathogens in a systematic manner. This response is therefore not too specific and phagocytosis occurs, that is to say the cells absorb and break down pathogens.
- Adaptive (acquired) immunity, which on the other hand is slowly put into place, but is highly specific. The cells that intervene are capable of learning to recognise a specific pathogen and of developing very effective means of defence. Producing antibodies is one of the methods developed by the organism in this case.
There are very few compounds that have been scientifically proven capable of stimulating the immune system. This is notably the case of beta-glucans. Beta-(1,3/1,6)-glucans are extracts from the cell walls of baker’s yeast (Saccharomyces cerevisiae) that are recognised by macrophages and are thus able to activate them. Beta-glucans are indeed also present on the cell walls of certain fungi and bacteria, they are therefore naturally recognised by innate immune cells as components of pathogens.
A study was undertaken by a team of Brazilian and American researchers with the aim of comparing immune responses to beta-glucans in 4 different species : mice, dogs, piglets and chicks. For this, during 28 days, the animals either received oral supplementation with one of two different types of beta-glucans, or did not receive supplementation. The supplemented animals were all given the same quantity of beta-glucans per kg of bodyweight, no matter the species.
In all 4 species, researchers observed a positive effect of beta-glucans on:
- The production of a particular molecule called IL2. This molecule is a cytokine, that is to say that it plays a significant role in regulating the immune response. Indeed, IL2 has the capacity to stimulate the response not only of innate immune cells but also of adaptive immune cells,
- The ability of innate immune cells to phagocyte pathogens,
- The production of antibodies directed towards an unknown molecule (antigen), that is thus potentially dangerous to the body.
This work therefore confirmed the effects of beta-glucans as having an immunity stimulating effect, and this, in four different animal species, and what is more, of different sexes and ages. An older study had previously demonstrated that the same beta-glucans increased resistance to bacterial infection in fish1. Their ability to stimulate the immune system is therefore proven in many species.
As a reminder, in the horse, it has been demonstrated that beta-glucans stimulated vaccination responses in Trotting horses in training (see the scientific sheet on beta-glucans), and also improved colostrum quality in the mare2.
de Oliveira, C. A. F., Vetvicka, V. & Zanuzzo, F. S. β-Glucan successfully stimulated the immune system in different jawed vertebrate species. Comp. Immunol. Microbiol. Infect. Dis. 62, 1–6 (2019).
1. Pilarski, F., Ferreira de Oliveira, C. A., Darpossolo de Souza, F. P. B. & Zanuzzo, F. S. Different β-glucans improve the growth performance and bacterial resistance in Nile tilapia. Fish Shellfish Immunol. 70, 25–29 (2017).
2. Krakowski, L. et al. The effect of nonspecific immunostimulation of pregnant mares with 1,3/1,6 glucan and levamisole on the immunoglobulins levels in colostrum, selected indices of nonspecific cellular and humoral immunity in foals in neonatal and postnatal period. Vet. Immunol. Immunopathol. 68, 1–11 (1999).