###### Abstract  
This paper presents raw plant materials and their characteristic compounds which may affect the immune system. Plant-derived agents in specific doses affect the body's non-specific, antigen-independent defense system. They have immunostimulatory effects on the entire immune regulatory system. They can enhance the immune response through various factors such as macrophages, leukocytes, and granulocytes, as well as through mediators released by the cellular immune system. This paper was inspired by the threats caused by the COVID-19 pandemic. The proper functioning of the immune system is important in limiting the effects of viral infection and restoring the normal functioning of the body. This paper also emphasizes the importance of the skillful use of plant immunostimulants by potential patients, but also by those who prescribe drugs. It is important not only to choose the right plant drug but above all to choose the correct dose and duration of treatment. plant immunomodulators; sources; principles of use; effectiveness; alkal amide complex; cichoric acid; echinacos +
Footnote †: journal: Medical  
granulocytes, among others) and/or modulation of the autonomic nervous system to restore the normal, natural functions of the body [9; 10]. Its central element is the activation of macrophages--cells produced by the bone marrow that primarily stimulate the process of phagocytosis [11]. They are also responsible for releasing numerous substances with vast biological properties affecting the immune system, such as tumor necrosis factor (TNF-\(\alpha\)) and interleukins (IL). TNF-\(\alpha\) (tumor necrosis factor) is a protein substance involved in the immune response and inflammatory process [12]. Essential biological functions of the factor are stimulation of B, T, and natural killer (NK) lymphocytes, stimulation of the immune response to the presence of tumor cells by affecting apoptosis (programmed cell death process), and inhibition of proliferation of tumor cells [13]. The stimulus for its production is also provided by bacterial lipopolysaccharide, interleukin 1, and \(\gamma\)-interferon (IFN). More recently, the possibility of TNF influencing the regeneration of nerve cells in the brain has been identified. However, it should be noted that negative aspects of this factor--induction of tumor cell proliferation and enhancement of the inflammatory process--are also suggested. For this reason, great caution should be exercised against compounds that contribute to increased secretion of the TNF factor [14]. Interleukins (IL) are cytokines involved in the inflammatory process, with a broad spectrum of action. IL-1 affects the formation of B and T lymphocytes (specific immune response). IL-6 stimulates B lymphocytes formation and inhibits TNF reflux. IL-10, an anti-inflammatory cytokine, inhibits the production of pro-inflammatory cytokines such as IL-2, IL-3, \(\gamma\)-interferon, and TNF. Finally, IL-12 differentiates T lymphocytes and activates NK cells [15; 16]. The use of immunositulants inconsistently with treatment (too high doses and excessive duration of use) can cause the immune system to become deregulated or even shut down, leading to increased chronic inflammation. Consequently, the body's defense system is activated and the destructive process can gradually be directed against the body's cells. The continued stimulation of B and T lymphocyte production can lead to autoimmune diseases such as multiple sclerosis [17]. Among the plant raw materials that have so far been proven, by pharmacological and clinical studies, to have an immune-stimulating effect are, first of all, _Echinaceae purpureae herba recus_ and _radix_[18] and _Echinaceae pallidae radix_, and to a lesser extent, _Echinaceae angustifoline radix_ and _Aloe arboreae folintum_, as well as _Panax quinafebdii radix_. Polysaccharidesides in these plant raw materials increase the number of lymphocytes and sensitize foreign substances to the effect of phagocytosis (opsonization) [19].