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The article characterises platelets, pointing out the role and contribution of their numerous receptors determining their specific and broad immune activity. Three types of platelet receptors are described, that is, extracellular and intracellular receptors-TLR (toll-like receptors), NLR (NOD-like receptor), and RLR (RIG-I-like receptor); extracellular receptors-selectins and integrins; and their other extracellular receptors-CLR (C-type lectin receptor), CD (cluster of differentiation), TNF (tumour necrosis factor), among others. Outlining the contribution of these numerous platelet receptors to the intravascular immunity, it has been shown that they are formed by their fusion with pathogen-associated molecular patterns (PAMPs), damage-associated molecular patterns (DAMPs), and lifestyle-associated molecular patterns (LAMPs). They are initiating and effector components of signal transduction of these cells, and their expression and quantity determine the specific and broad functions of platelets towards influencing vascular endothelial cells, but mainly PRRs (pattern recognition receptors) of blood immune cells. These facts make platelets the fundamental elements that shape not only intravascular homeostasis, as previously indicated, but they become the determinants of immunity in blood vessels. Describing the reactions of the characterised three groups of platelet receptors with PAMP, DAMP and LAMP molecules, the pathways and participation of platelets in the formation and construction of intravascular immune status, in physiological states, but mainly in pathological states, including bacterial and viral infections, are presented, making these cells essential elements in the health and disease of mammals, including humans.

Cyclophosphamide (CPAm) is a widely used chemotherapeutic agent that exhibits potent anti-cancer properties but is often associated with debilitating side effects. Despite its efficacy, the management of CPAm-induced toxicities remains a significant clinical challenge. There has been growing interest in exploring complementary and alternative therapies to mitigate these adverse effects in recent years, and this may be a chance for the earthworm-derived preparation, Venetin-1. Its rich composition of bioactive compounds has demonstrated promising pharmacological properties, including anti-inflammatory, antioxidant, and immunomodulatory effects. These properties suggest its potential to counteract various systemic toxicities induced by CPAm. We conducted a comprehensive study to investigate the effect of Venetin-1 on cyclophosphamide-induced toxicity. Mice were administered CPAm for four days, followed by application of the earthworm preparation in two doses (50 mg/kg and 100 mg/kg b.w). Importantly, the preparation did not cause any side effects in all mice, ensuring the safety of the intervention. We then determined global changes in the proteome using proteomics and quantitative SWATH-MS analysis, which is a robust and reliable method. This allowed us to identify up- and downregulated proteins in each studied group, providing valuable insights into the mechanism of action of Venetin-1. As shown by the results, Venetin-1 had a significant effect on the proteome of mouse lung tissue. It was possible to determine quantitative changes in 400 proteins, and the analysis after administration of Venetin-1 showed a change in the global proteomic profile from upregulated to down-regulated. The stimulating properties of the preparation concerning the complement system were also confirmed in a separate validation experiment. Venetin-1 shows promise in reducing the harmful effects of cyclophosphamide on lung tissue. It encourages tissue regeneration, reduces inflammation, supports autophagy, and boosts the immune system. However, more research is needed to thoroughly elucidate and describe the benefits of Venetin-1., (© 2024. The Author(s).)

In this paper, the characteristics of 40 so far described virophages-parasites of giant viruses-are given, and the similarities and differences between virophages and satellite viruses, which also, like virophages, require helper viruses for replication, are described. The replication of virophages taking place at a specific site-the viral particle factory of giant viruses-and its consequences are presented, and the defence mechanisms of virophages for giant virus hosts, as a protective action for giant virus hosts-protozoa and algae-are approximated. The defence systems of giant viruses against virophages were also presented, which are similar to the CRISPR/Cas defence system found in bacteria and in Archea. These facts, and related to the very specific biological features of virophages (specific site of replication, specific mechanisms of their defensive effects for giant virus hosts, defence systems in giant viruses against virophages), indicate that virophages, and their host giant viruses, are biological objects, forming a 'novelty' in biology.

Rabbit haemorrhagic disease viruses (RHDV) belong to the family Caliciviridae, genus Lagovirus europaeus , genogroup GI, comprising four genotypes GI.1-GI.4, of which the genotypes GI.1 and GI.2 are pathogenic RHD viruses, while the genotypes GI.3 and GI.4 are non-pathogenic RCV ( Rabbit calicivirus ) viruses. Among the pathogenic genotypes GI.1 and GI.2 of RHD viruses, an antigenic variant of RHDV, named RHDVa-now GI.1a-RHDVa, was distinguished in 1996; and in 2010, a variant of RHDV-named RHDVb, later RHDV2 and now GI.2-RHDV2/b-was described; and recombinants of these viruses were registered. Pathogenic viruses of the genotype GI.1 were the cause of a disease described in 1984 in China in domestic ( Oryctolagus ( O. ) cuniculus domesticus ) and wild ( O. cuniculus ) rabbits, characterised by a very rapid course and a mortality rate of 90-100%, which spread in countries all over the world and which has been defined since 1989 as rabbit haemorrhagic disease. It is now accepted that GI.1-RHDV, including GI.1a-RHDVa, cause the predetermined primary haemorrhagic disease in domestic and wild rabbits, while GI.2-RHDV2/b cause it not only in rabbits, including domestic rabbits' young up to 4 weeks and rabbits immunised with rabbit haemorrhagic disease vaccine, but also in five various species of wild rabbits and seven different species of hares, as well as wild ruminants: mountain muskoxen and European badger . Among these viruses, haemagglutination-positive, doubtful and harmful viruses have been recorded and described and have been shown to form phylogenogroups, immunotypes, haematotypes and pathotypes, which, together with traits that alter and expand their infectious spectrum (rabbit, hare, wild ruminant, badger and various rabbit and hare species), are the determinants of their pathogenicity (infectivity) and immunogenicity and thus shape their virulence. These relationships are the aim of our consideration in this article.

It is assumed that cells corresponding to innate lymphoid cells (ILCs) in humans, in addition to lymphoid tissue inducer cells (LTi), are also found in teleosts. In this systematic group of organisms, however, they are a poorly understood cell population. In contrast to the data on ILCs in humans, which also remain incomplete despite advanced research, in teleosts, these cells require much more attention. ILCs in teleosts have been presented as cells that may be evolutionary precursors of NK cells or ILCs identified in mammals, including humans. It is a highly heterogeneous group of cells in both humans and fish and their properties, as revealed by studies in humans, are most likely to remain strictly dependent on the location of these cells and the physiological state of the individual from which they originate. They form a bridge between innate and adaptive immunity. The premise of this paper is to review the current knowledge of ILCs in teleosts, taking into account data on similar cells in humans. A review of the knowledge concerning these particular cells, elements of innate immunity mechanisms as equivalent to, or perhaps dominant over, adaptive immunity mechanisms in teleosts, as presented, may inspire the need for further research., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The paper presents virophages, which, like their host, giant viruses, are "new" infectious agents whose role in nature, including mammalian health, is important. Virophages, along with their protozoan and algal hosts, are found in fresh inland waters and oceanic and marine waters, including thermal waters and deep-sea vents, as well as in soil, plants, and in humans and animals (ruminants). Representing "superparasitism", almost all of the 39 described virophages (except Zamilon) interact negatively with giant viruses by affecting their replication and morphogenesis and their "adaptive immunity". This causes them to become regulators and, at the same time, defenders of the host of giant viruses protozoa and algae, which are organisms that determine the homeostasis of the aquatic environment. They are classified in the family Lavidaviridae with two genus (Sputnikovirus, Mavirus). However, in 2023, a proposal was presented that they should form the class Maveriviricetes, with four orders and seven families. Their specific structure, including their microsatellite (SSR-Simple Sequence Repeats) and the CVV (cell-virus-virophage, or transpovirion) system described with them, as well as their function, makes them, together with the biological features of giant viruses, form the basis for discussing the existence of a fourth domain in addition to Bacteria, Archaea, and Eukaryota. The paper also presents the hypothetical possibility of using them as a vector for vaccine antigens.

This paper presents the role of macrophage efferocytosis, the process of elimination of apoptotic bodies-elements formed during vascular atherosclerosis. The mechanisms of macrophage efferocytosis are presented, introducing the specific signals of this process, that is, 'find me', 'eat me' and 'don't eat me'. The role of the process of efferocytosis in the formation of vascular atherosclerosis is also presented, including the factors and mechanisms that determine it, as well as the factors that determine the maintenance of homeostasis in the vessels, including the formation of vascular atherosclerosis., (© 2022 The Scandinavian Foundation for Immunology.)

The paper presents the problem of intestinal mucosa immunity in teleost fish. The immunity of the intestinal mucosa in teleost fish depends on the elements and mechanisms with different organizational/structural and functional properties than in mammals. The organization of the elements of intestinal mucosal immunitya in these animals is associated with the presence of immune cells that fulfil the functions assigned to the induction and effector sites of mucosal immunity in mammals; they are located at various histological sites of the mucosa - in the lamina propria (LP) and in the surface epithelium. The presence of mucosa-associated lymphoid tissue (MALT) has not been demonstrated in teleost fish, and the terminology used in relation to the structure and function of the mucosa immunity components in teleost fish is inadequate. In this article, we review the knowledge of intestinal mucosal immunity in teleost fish, with great potential for knowledge and practical applications especially in the field of epidemiological safety. We discuss the organization and functional properties of the elements that determine this immunity, according to current data and taking into account the tissue definition and terminology adopted by the Society for Mucosal Immunology General Assembly (13th ICMI in Tokyo, 2007)., Competing Interests: Declaration of competing interest The authors declare no confict of interest/competing interest., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Haematopoiesis in fish and mammals is a complex process, and many aspects regarding its model and the differentiation of haematopoietic stem cells (HSCs) still remain enigmatic despite advanced studies. The effects of microenvironmental factors or HSCs niche and signalling pathways on haematopoiesis are also unclear. This review presents Danio rerio as a model organism for studies on haematopoiesis in vertebrates and discusses the development of this process during the embryonic period and in adult fish. It describes the role of the microenvironment of the haematopoietic process in regulating the formation and function of HSCs/HSPCs (hematopoietic stem/progenitor cells) and highlights facts and research areas important for haematopoiesis in fish and mammals., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Stosik, Tokarz-Deptuła and Deptuła.)

Lagovirus europaeus/GI.1 causes a fatal viral condition in rabbits characterized by acute viral hepatitis and disseminated intravascular coagulation. Due to rapid viral and environmental changes variants (Lagovirus europaeus/GI.1a and GI.2) have appeared and few immunological studies were performed. The aim of the study was to determine innate and adaptive immunity parameters in rabbits infected with six Lagovirus europeus/GI.1a viruses. To achieve the goal several methods were used, i.e. cytometry, microscopy, biochemical and cytochemical tests, spectrophotometry. The results show that three immunotypes exists among the studied strains and they differ in innate (mainly) and adaptive immunity, partly depending on hemagglutination. The peak of changes is 24 h post infection in phagocytosis markers of polymorphonuclear cells and CD8 + T cells. Lagovirus europaeus/GI.1a strains differ from Lagovirus europaeus/GI.1 in terms of immunological response based on our previous work concerning the same parameters in immunological response against this disease., (© 2021. The Author(s).)

The article presents the function of platelets in inflammation as well as in bacterial and viral infections, which are the result of their reaction with the endovascular environment, including cells of damaged vascular endothelium and cells of the immune system. This role of platelets is conditioned by biologically active substances present in their granules and in their specific structures - EV (extracellular vesicles)., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Tokarz-Deptuła, Palma, Baraniecki, Stosik, Kołacz and Deptuła.)

Immunological memory can be regarded as the key aspect of adaptive immunity, i.e. a specific response to first contact with an antigen, which in mammals is determined by the properties of T, B and NK cells. Re-exposure to the same antigen results in a more rapid response of the activated specific cells, which have a unique property that is the immunological memory acquired upon first contact with the antigen. Such a state of immune activity is also to be understood as related to "altered behavior of the immune system" due to genetic alterations, presumably maintained independently of the antigen. It also indicates a possible alternative mechanism of maintaining the immune state at a low level of the immune response, "directed" by an antigen or dependent on an antigen, associated with repeated exposure to the same antigen from time to time, as well as the concept of innate immune memory, associated with epigenetic reprogramming of myeloid cells, i.e. macrophages and NK cells. Studies on Teleostei have provided evidence for the presence of immunological memory determined by T and B cells and a secondary response stronger than the primary response. Research has also demonstrated that in these animals macrophages and NK-like cells (similar to mammalian NK cells) are able to respond when re-exposed to the same antigen. Regardless of previous reports on immunological memory in teleost fish, many reactions and mechanisms related to this ability require further investigation. The very nature of immunological memory and the activity of cells involved in this process, in particular macrophages and NK-like cells, need to be explained. This paper presents problems associated with adaptive and innate immune memory in teleost fish and characteristics of cells associated with this ability., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Interferons (IFNs) are proteins of vital importance in the body's immune response. They are formed in different types of cells and have been found in fish, amphibians, reptiles and mammals. Two types of IFN have been found in ray-finned fish (Superclass: Osteichthyes, Class: Actinopterygii) so far, i.e. IFN type I (IFN I) and IFN type II (IFN II), while the presence of IFN type III (IFN III), which is found in phylogenetically older cartilaginous fishes, was not confirmed in this taxonomic group of vertebrates. Currently, type I IFN in Actinopterygii is divided into three groups, I, II and III, within which there are subgroups. These cytokines in these animals show primarily antiviral activity through the use of a signalling pathway JAK-STAT (Janus kinases - Signal transducer and activator of transcription) and the ability to induce ISG (IFN-stimulated genes) expression, which contain ISRE complexes (IFN-stimulated response elements). On the other hand, in Perciformes and Cyprinidae, it was found that type I/I interferons also participate in the antimicrobial response, inter alia, by inducing the expression of the inducible nitric oxide synthase (iNOS) and influencing the production of reactive oxygen species (ROS) in cells carrying out the phagocytosis process., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Red blood cells (RBCs)-erythrocytes-of Osteichthyes are primarily known for their involvement in the process of gas exchange and respiration. Currently, physiological properties of RCBs in fish should also include their ability to participate in defense processes as part of the innate and adaptive immune mechanisms. In response to viruses, bacteria, and fungi or recombinant nanoparticles, they can modulate expression of genes responsible for immune reactions, influence activity of leukocytes, and produce cytokines, antimicrobial peptides, and paracrine intercellular signaling molecules. Via the complement system (CR1 receptor) and owing to their phagocytic properties (erythrophagocytosis), RBCs of Osteichthyes can eliminate pathogens. In addition, they are probably involved in the immune response as antigen-presenting cells via major histocompatibility complex class II antigens., (Copyright © 2020 Stosik, Tokarz-Deptuła, Deptuła and Deptuła.)

Based on analysis of available genome sequences, five gene lineages of MHC class I molecules (MHC I-U, -Z, -S, -L and -P) and one gene lineage of MHC class II molecules (MHC II-D) have been identified in Osteichthyes. In the latter lineage, three MHC II molecule sublineages have been identified (MHC II-A, -B and -E). As regards MHC class I molecules in Osteichthyes, it is important to take note of the fact that the lineages U and Z in MHC I genes have been identified in almost all fish species examined so far. Phylogenetic studies into MHC II molecule genes of sublineages A and B suggest that they may be descended from the genes of the sublineage named A/B that have been identified in spotted gar ( Lepisosteus oculatus ). The sublineage E genes of MHC II molecules, which represent the group of non-polymorphic genes with poor expression in the tissues connected with the immune system, are present in primitive fish, i.e . in paddlefish, sturgeons and spotted gar ( Lepisosteus oculatus ), as well as in cyprinids ( Cyprinidae ), Atlantic salmon ( Salmo salar ), and rainbow trout ( Oncorhynchus mykiss ). Full elucidation of the details relating to the organisation and functioning of the particular components of the major histocompatibility complex in Osteichthyes can advance the understanding of the evolution of the MHC molecule genes and the immune mechanism., Competing Interests: Conflict of Interest Conflict of Interests Statement: The authors declare that there is no conflict of interests regarding the publication of this article., (© 2020 M. Stosik et al. published by Sciendo.)

The European rabbit (Oryctolagus cuniculus) is a good model in biomedicine used in research on several human diseases. The reference values of B and T cells and their subpopu- lations are very important to understand how the adaptive immune system is responding to infectious agents. The aim of this study was to determine values of B and T cells and their subpopulations in Polish mixed-breed rabbits, considering seasons of the year and sex. The study was performed on 200 Polish mixed-breed rabbits and the percentage of B and T lymphocytes was measured cytometrically using mouse anti-rabbit antibodies. The study revealed that the season of the year and sex of the animals affected the percentage of B- and T-cells and their subpopulations in peripheral blood. Statistically significant values of CD19+ B-cells in spring and autumn, of T CD5+ cells in spring and winter, of T CD4+ in spring, summer, autumn and winter, of T CD8+ in winter and of T CD25+ in spring were noted. Generally the highest values were found mainly in warm part of the year, while the lowest in colder months. A statistical significance was also observed between males and females - changes were found in T CD4+ and T CD25+ lymphocytes in spring, T CD8+ cells in winter and higher percentage was generally obtained in females than in males. The only exception was the T CD5+ subpopulation in which no differences were observed between the sexes and throughout the year. This is the first paper on adaptive immune system cell values in the European rabbit of domestic breeds., (Copyright© by the Polish Academy of Sciences.)

Innate lymphoid cells (ILCs) are a recently described group of immune cells that can regulate homeostasis and protect mammalian organisms, including humans, from infections and diseases. Considering this, ILC research is still ongoing to better understand the biology of these cells and their roles in the human body. ILCs are a multifunctional group of immune cells, making it important for the medical community to be familiar with the latest research about the ILC families and their functions in selected disease states, such as cancer formation, metabolic disorders and inflammation. By discovering the roles of ILC populations and their participation in many disorders, we can improve disease diagnostics and patient healthcare., Competing Interests: The authors declare no conflict of interest., (Copyright: © 2019 Termedia & Banach.)

The discovery of giant viruses has revolutionised the knowledge on viruses and transformed the idea of three domains of life. Here, we discuss the known protozoal giant viruses and their potential to infect also humans and animals.

The discovery of the NET network (neutrophil extracellular trap) has revolutionized the perception of defense mechanisms used by neutrophils in infections and non-infectious states, as this mechanism proves the complexity of the ways in which neutrophils can act in the organism. The paper describes the NET network and its participation in bacterial, viral, fungal and parasitic infections, both in a positive and a negative aspect. In addition, attention was paid to the participation of NETs in the course of autoimmune diseases, cancer, as well as its impact on pregnancy and fertility in mammals., Competing Interests: Competing interestsThe authors declare that they have no competing interests.

Thrombocytes in vertebrates other than mammals, inter alia in fish, are analogues of platelets in mammals. In Osteichthyes, these cells take part in haemostatic processes, including aggregation and release reactions in cases of blood vessel damage, and in the immune response development as well. This paper discusses the development of thrombocytes in Osteichthyes, taking into account the need to make changes to the concept of grouping progenitor cells as suggested in the literature. The following pages present the morphological and cytochemical properties of thrombocytes as well as their defence functions, and also point out differences between thrombocytes in fish and platelets in mammals. The paper further highlights the level of thrombocytes' immune activity observed in fish and based on an increased proportion of these cells in response to antigenic stimulation, on morphological shifts towards forms characteristic of dendritic cells after antigenic stimulation and on the presence of surface structures and cytokines released through, inter alia, gene expression of TLR receptors, MHC class II protein-coding genes and pro-inflammatory cytokines. The study also points out the need to recognise thrombocytes in Osteichthyes as specialised immune cells conditioning non-specific immune mechanisms and playing an important role in affecting adaptive immune mechanisms., Competing Interests: Conflict of Interest Conflict of Interests Statement: The authors declare that there is no conflict of interests regarding the publication of this article.

Melanomacrophages (MMs) are phagocytizing cells with high amounts of pigments including melanin which can be found in a number of cold-blooded species. In Osteichthyes, these cells cluster to form so-called melanomacrophage centres (MMCs), which are predominantly present in the stroma of hematopoietic and lymphoid tissues, that is, in the kidney and spleen. The functionality of MMs and MMCs results from their involvement and role in the defence reactions, related to both the innate and the adaptive immune mechanisms, and in processes unrelated to defence functions as well. There is evidence that MMCs are structurally and functionally similar to mammals' germinal centres (GCs). It appears that mature IgM+ B cells in Osteichthyes can be the equivalent of mIgM+ centrocytes in mammals, whereas MMs can be, in terms of the function, the equivalent of follicular dendritic cells (FDCs), and MMCs can be, in terms of clustered specific cells, the equivalent of GCs. This paper presents selected facts about the structural and functional similarity between GCs and MMCs and about the involvement and role of MMCs and MMs in the immune response. The facts help get a proper picture of the location of MMs and MMCs within the structure of the fish immune system, also in the context of their evolutionary relationship with GCs and of the possibility of pointing out the evolutionary closeness between MMCs in Osteichthyes and GCs in mammals., Competing Interests: The authors declare no conflict of interest.

Five years after being discovered in 2003, some giant viruses were demonstrated to play a role of the hosts for virophages, their parasites, setting out a novel and yet unknown regulatory mechanism of the giant viruses presence in an aqueous. So far, 20 virophages have been registered and 13 of them have been described as a metagenomic material, which indirectly impacts the number of single- and multi-cell organisms, the environment where giant viruses replicate.

In contrast to adaptive antibodies, natural antibodies are present in a non-immunised organism from birth, and they do not include anti-Gal antibodies and/or anti-Gal natural antibodies, which are developed as a result of the effect of the α -Gal epitope and physiological flora. Natural antibodies are the first line of the organism's defence before the formation of the immunity created via the stimulation of elements that determine specific and non-specific immunity. This is especially important in the case of infants. Despite the fact that natural antibodies differ in their function from adaptive antibodies, they are polyreactive and they detect autoantigens and new antigenic determinants. Natural antibodies are formed from the subpopulation of B lymphocytes, mainly B1 lymphocytes and B lymphocytes of the marginal zone. This phenomenon is supported by the fact that when the quantity of these cells in the organism decreases, which happens with age, the level of natural antibodies also decreases and the risk of illnesses of old age becomes higher. During ontogenesis, these antibodies participate in many physiological processes, including the "support" of the immune system and homeostasis, the prevention of inflammation, infections and other pathological states, such as autoimmune and cardiovascular diseases, or the process of carcinogenesis. The best known natural antibody is IgM, but the role of IgGs and IgAs is also considered important. Nowadays, many researchers also mention intravenous immunoglobulins, which are used in the treatment of numerous illnesses, and there are discussions on the possibility of increasing their potential if they were based on natural antibodies., Competing Interests: The authors declare no conflict of interest.

This article reviews immunological memory cells, currently represented by T and B lymphocytes and natural killer (NK) cells, which determine a rapid and effective response against a second encounter with the same antigen. Among T lymphocytes, functions of memory cells are provided by their subsets: central memory, effector memory, tissue-resident memory, regulatory memory and stem memory T cells. Memory T and B lymphocytes have an essential role in the immunity against microbial pathogens but are also involved in autoimmunity and maternal-fetal tolerance. Furthermore, the evidence of immunological memory has been established for NK cells. NK cells can respond to haptens or viruses, which results in generation of antigen-specific memory cells. T, B and NK cells, which have a role in immunological memory, have been characterized phenotypically and functionally. During the secondary immune response, these cells are involved in the reaction against foreign antigens, including pathogens, and take part in autoimmune diseases, but also are crucial to immunological tolerance and vaccine therapy., Competing Interests: The authors declare no conflict of interest.

The fish immune system is extremely complex and has considerable adaptive potential. In Osteichthyes, the system is formed by lymphopoietic organs which are important for the differentiation and maturation of the immune system cells. These organs include the anterior kidney (phronephros), the thymus, the spleen, the posterior kidney (mesonephros), and mucosa-associated lymphoid tissues (MALT). Apart from the lymphocytic organs and the MALT system, the immune system components include defensive cells and their products. Those identified in fish include, inter alia, monocytes/macrophages, melanomacrophages, neutrophilic granulocytes, thrombocytes, B cells, plasma cells, and T cells. The roles of the individual components of the organisation of the immune system, the organs, and lymphoid tissue as well as the constituents conditioning the innate and adaptive immunity mechanisms are considered equally important, especially in the context of functional interdependence. The progress in the exploration of the processes of specific humoral immunity in Osteichthyes and the possibilities of their practical application is increasingly promising in view of the expected need for protection of fish against diseases. The paper discusses selected issues concerning recent knowledge about haematopoiesis of B cells, plasmablasts, plasma cells, and immunoglobulins (IgM, IgD, IgT/IgZ)., Competing Interests: The authors declare no conflict of interest.

Rabbit haemorrhagic disease virus (RHDV) induces a highly contagious and extremely lethal disease that fulfils many requirements of an animal model of fulminant hepatic failure (FHF); however, the pathogenesis of RHD has still not been fully elucidated. Cytokines play an important role in regulation of the immune response and pathogenesis of many diseases, including those caused by viral infections. Furthermore, recent studies indicate a role of the immune response, especially peripheral blood leukocytes (PBL), in the pathogenesis of RHD. Thus, in the present study we investigated the expression of IL-1Ra, IL-6, IL-8, IL-18, TNF-α and IFN-γ genes in PBL of RHDV-infected rabbits. We also compared the expression of genes encoding these cytokines in rabbits with different course of RHDV infection (in animals that died 36 h post infection or survived even over 60 h after infection). The study revealed increased expression of genes encoding pro-inflammatory cytokines: IL-6, IL-8, TNF-α, IFN-γ in PBL of RHDV-infected rabbits. Moreover, the level of cytokine gene expression depended on the course of RHD. Hence, the results obtained indicate the potential role of these cytokines in RHDV infection and their influence on the survival time of infected rabbits., (Copyright © 2017. Published by Elsevier Ltd.)

The objective of the study was to determine values of apoptosis for peripheral blood lymphocytes and granulocytes, including dependency on the season of the year, in Polish mixed-breed rabbits and in mixed-breed rabbits with the addition of blood of meat-breed rabbits. The study was carried out in four seasons of the year (spring, summer, autumn, winter) involving 120 Polish mixed-breed rabbits - group I, and 120 Polish mixed-breed rabbits with addition of meat-breed rabbit blood - group II. Assessment of apoptosis of lymphocytes and granulocytes was performed using as FACScan cytometer by Becton Dickinson with FACSDiva software (USA), using as ApoFluor® Green Caspase reagent kit (MP Biomedicals, USA) to detect the activity of the total caspase pool 1, 3, 4, 5, 6, 7, 8, 9 in granulocytes and lymphocytes of rabbit peripheral blood. The results for apoptosis of lymphocytes and granulocytes in peripheral blood in the animals investigated (group I and II) were subjected to statistical analysis with the t'Student test at p=0.05. It was noted that, in rabbits from group I, the values for apoptosis of lymphocytes were the highest in winter and autumn (36.02% and 31.24%, respectively), and the lowest in spring and summer (26.73% and 22.72%, respectively), whereas in the case of granulocytes the highest values were in summer and spring (14.69% and 12.95%, respectively), and the lowest in winter and autumn (8.16% and 8.57%, respectively). In mixed-breed rabbits with the addition of meat-breed blood (group II), the values for apoptosis of lympocytes were the highest in spring (29.13%), and the lowest in summer (25.43%); whereas in the case of granulocytes the highest values were in summer and spring (14.0% and 11.15%, respectively), and the lowest in autumn and winter (7.46% and 7.64%, respectively).

Interferons (IFNs) are pivotal regulators of immunological processes. This paper describes mainly type I interferons -α and -β and their recently recounted signaling pathways, especially connected with ISGs - interferon stimulated genes, having a crucial role in regulating IFN recruitment. Moreover, the paper shows the data on the role of interferons -α and -β in infections - not only commonly known viral infections, but also bacterial, fungal and parasitic.

Butyrophilins belonging to the immunoglobulin superfamily are new immune system regulators because they are present on lymphocytes, dendritic cells, monocytes, macrophages, neutrophils and eosinophils, and they exert a stimulatory and (or) inhibitory effect on them. The role of butyrophilins is associated and results from their similarity to the regulatory B7 protein family involved in the modulation of immune phenomena. Butyrophilins are glycoproteins built of two extracellular immunoglobulin domains, stabilized with disulfide bonds: constant IgC, and variable IgV and a transmembrane region. Most of these proteins contain a conserved domain encoded by a single exon - B30.2, also referred to as PRYSPRY. In humans, the family of butyrophilins includes 7 butyrophilin proteins, 5 butyrophilin-like proteins and the SKINT-like factor. Butyrophilins have been also demonstrated to play a role in various infections, e.g. tuberculosis or diseases that include sarcoidosis, systemic lupus erythematosus, rheumatoid arthritis, genetic metabolic diseases, ulcerative colitis, cancer and kidney disease., Competing Interests: The authors declare no conflict of interest.

The aim of the study was to establish if haemagglutination of rabbit haemorrhagic disease virus (RHDV) affects haematological picture of peripheral blood in rabbits and the pathogenicity of the virus. The study analyzed white and red blood cell picture in rabbits experimentally infected with two non-haemagglutinating (HA-) RHDV strains (Frankfurt and Asturias) and one strain with variable haemagglutination capacity (HA+/-) (Hagenow). Studies with HA- and HA +/- are rare and relate only to 4 HA- strains (2 RHDV: BLA and Rainham; 2 RHDVa: Pv97 and 9905) and 1 HA+/- RHDV strain: ŻD, where less changes in haematological indices and less pathogenicity were observed. We found that changes caused by HA- Frankfurt strain were related to the number of neutrophils and thrombocytes, while in HA- strain Asturias, in thrombocytes and leukocytes. Changes evoked by HA+/- Hagenow strain pertained to the number of eosinophils, thrombocytes, leukocytes, monocytes, and concentration of hemoglobin. Mortality caused by the Frankfurt strain was 100% between 36 and 48 h post infection (p.i.), while that caused by Asturias strain was 100% between 24 and 36 h p.i., and that observed in case of Hagenow strain was 90% between 36 and 48 h p.i. The changes in haematological picture caused by the HA- and HA+/- RHDV strains were less intensive than those found in case of the HA+ RHDV strains, which cannot be confirmed for pathogenicity, and is not in line with the existing hypothesis suggesting higher pathogenicity in HA+ viruses.

Commensal bacteria are microorganisms that occur among others in the gastrointestinal, respiratory and urogenital tract not exhibit the characteristics of pathogenicity, and act on the immune system and the metabolism of macroorganism and "create" protective barrier against pathogenic bacteria. Currently, it is estimated that the number of commensal bacteria inhabiting in and on human, are more than ten times the number of cells that build the body. The composition of these microorganisms depends on health and physiological status of macroorganism, including its immune status, but also largely on environmental factors (living and diet). These bacteria affecting the immune system in the gastrointestinal, respiratory and urogenital tract, stimulate the synthesis of a number of immunological substances that interact multiphase, for example: blocking the adhesion of pathogenic microorganisms and to reduce or entirely eliminate their influence on the contact and macroorganism.

Rabbit haemorrhagic disease (RHD) is a highly morbid and mortal viral infection of European rabbits. This disease is one of the main causes of death in wild rabbits, and results in large economic losses in farms of rabbits worldwide. Although the first outbreak of this disease was noted in 1984, the pathogenesis of RHD and mechanisms of RHDV (rabbit haemorrhagic disease virus) pathogenecity have still not been fully elucidated. Recent studies indicate a role of the immune response, especially peripheral blood leukocytes (PBL), in the pathogenesis of this disease. Thus, in the present study we investigated the expression of IL-1β, IL-2, IL-10, TNF-β and GM-CSF genes in PBL of RHDV-infected rabbits. We also compared the expression of genes encoding these cytokines in rabbits with different course of RHDV infection (in animals that died 36h postinfection or survived until 60th h after infection). The study revealed that three (IL-10, TNF-β and GM-CSF) out of five investigated genes encoding cytokines showed increased expression in PBL of RHDV-infected rabbits, and the level of expression depended on the course of RHD. The results indicate the potential role of these cytokines in RHDV infection and their influence on the survival time of infected rabbits., (Copyright © 2016 Elsevier B.V. All rights reserved.)

During reaction to stress caused by viral infection, RNA granules are formed in order to protect mRNA. Stress granules (SG) and processing bodies (PB) provide cell homeostasis and mRNA stability. They are formed, for example, during polio virus and MRV (mammalian orthoreovirus) infections. Some viruses, such as influenza virus and HTLV-1 (Human T-lymphotropic virus 1), block the formation of granules. In addition, there are viruses like West Nile Virus, Hepatitis C Virus (HCV) or human Herpes viruses, which influence the functioning of the granules.

Coronins are a large family of proteins occurring in many eukaryotes. In mammals, seven coronin genes have been identified, evidencing that coronins 1 to 6 present classic coronin structure, while coronin 7 is a tandem coronin particle, without a spiral domain, although the best characterised coronin, in terms of both structure and function, is the mammalian coronin 1. It has been proven that they are related to regulation of actin dynamics, e.g. as a result of interaction with the complex of proteins Arp2/3. These proteins also modulate the activity of immune system cells, including lymphocyte T and B cells, neutrophils and macrophages. They are involved in bacterial infections with Mycobacterium tuberculosis, M. leprae and Helicobacter pylori and participate in the response to viral infections, e.g. infections of lymphocytic choriomeningitis virus (LCMV) and vesicular stomatitis Indiana virus (VSV). Also their involvement in autoimmune diseases such as lupus erythematosus has been recorded., Competing Interests: The authors declare no conflict of interest.

Fungi are omnipresent in the environment; hence they are frequent factors causing infections in humans and animals even if their immune system works correctly. These facts stimulated interest in and the will to understand the antifungal immunity mechanisms. It has been, however, evidenced that the immunological response to mycotic pathogens is related to the species and morphological form of the fungus. Nevertheless, it is assumed that always in the antifungal response, there are mechanisms of innate and adaptive immunity that cooperate with one another to eliminate such pathogens. It has been evidenced that the main elements of antifungal immunity are physical barriers of the organism, phagocytosis, cytotoxicity, and possibly trogocytosis of PMN and MN cells, as well as T-cells, and to a smaller extent B-cells, the proportion of which is principally related to their products activating the processes of PMN and MN cells. An important role in this immunity also belongs to PRR, which activate the main processes of phagocytosis and cytotoxicity of PMN, MN, NK and DC cells.

Influenza viruses are a significant cause of respiratory infections, causing 3-5 million clinical infections and 250-500 thousand deaths per year. Infections caused by the influenza virus induce a host immune response at the non-specific and specific level (defined as natural and acquired), which leads to limitation of virus replication. Moreover the elements of immunological memory are induced so that they can protect against subsequent infection by the influenza virus. However, there is still no effective way for the total elimination of this virus, and the only effective method to combat this pathogen appears to be vaccination, which through immune system activation greatly limits its spread. The present paper presents the immune reaction at different levels in response to the influenza virus after entering the body and the mechanisms of the influenza virus for avoiding reactions of the immune system, which correspond to its high variability at the molecular level. Moreover, in this paper we describe various methods of stimulating the organism's immune systems with different generations of vaccines and their effectiveness in the fight against this pathogen.

Mixed-breed rabbits in Poland are widely used for diagnostic and scientific research and as utility animals, therefore there is a need to know their immunological status, as well as their haematological status. In this study natural immunity factors were analyzed in Polish mixed-breed rabbits and Polish mixed-breed rabbits with addition of blood of meet-breed, considering the impact of sex and season of the year (spring, summer, autumn, winter) using measurement of non-specific cellular and humoral immunity parameters in peripheral blood. The study has revealed that there is a variety between the two commonly used mixed-breed types of rabbits, especially when sex and season is concerned, which is crucial for using these animals in experiments.

RHDV (rabbit haemorrhagic disease virus) is an etiologic factor of RHD (rabbit haemorrhagic disease), which is highly morbid and mortal viral infection of an adult European rabbit. Although three decades have passed since the first outbreak of rabbit haemorrhagic disease, the pathogenesis of RHD has still not been fully elucidated. It is known that RHDV replicates in the liver within the first hours following infection, causing necrotic and apoptotic cell death of hepatocytes. Anatomopathological changes are also observed in other organs of infected rabbits, i.e. lungs, spleen, kidneys, heart, as well as central nerve system. These changes leading to animals death are predominantly caused by systemic hemorrhagic diathesis with disseminated intravascular coagulation (DIC), appearing most likely as a consequence of liver cell loss through RHDV-induced apoptosis. In this paper, we presented previously described changes in biochemical and coagulation factors in RHDV infection.

In the paper we studied haematologic values, such as haemoglobin concentration, haematocrit value, thrombocytes, leucocytes: lymphocytes, neutrophils, basophils, eosinophils and monocytes in the pheral blood in Polish mixed-breeds with addition of meat breed blood in order to obtain the reference values which are until now not available for this animals. In studying this indices we took into consideration the impact of the season (spring, summer, autumn, winter), and sex of the animals. The studies have shown a high impact of the season of the year on those rabbits, but only in spring and summer. Moreover we observed that the sex has mean impact on the studied values of haematological parameters in those rabbits. According to our knowledge, this is the first paper on haematologic values in this widely used group of rabbits, so they may serve as reference values.

Innate lymphoid cells (ILC) is a newly described family of immune cells that are part of the natural immunity which is important not only during infections caused by microorganisms, but also in the formation of lymphoid tissue, tissue remodeling after damage due to injury and homeostasis tissue stromal cells. Family ILC cells form NK cells (natural killer) and lymphoid tissue inducer T cells (LTi), which, although they have different functions, are evolutionarily related. NK cells are producing mainly IFN-γ, whereas LTi cells as NKR+LTi like, IL-17 and/or IL-22, which suggests that the last two cells, can also represent the innate versions of helper T cell--TH17 and TH22. Third population of ILC is formed by cells with characteristics such as NK cells and LTi (ILC22)--which are named NK22 cells, natural cytotoxicity receptor 22 (NCR22) cells or NK receptor-positive (LTi NKR+) LTi cells. Fourth population of ILC cells are ILC17--producing IL-17, while the fifth is formed by natural helper type 2 T cells (nTH2), nuocyte, innate type 2 helper cells (IH2) and multi-potent progenitor type 2 cells (MPPtype2). Cells of the last population synthesize IL-5 and IL-13. It is assumed that an extraordinary functional diversity of ILC family, resembles T cells, probably because they are under the control of the corresponding transcription factors - as direct regulation factors, such as the family of lymphocytes T.

The study of the immune system started about a hundred years ago with the phagocytosis experiments of Mechnikov. That which is now referred to as non-specific cell-mediated immunity was quickly linked to studies related to, inter alia, the immunity determined by antibodies (humoral), which has long been considered as the first line of defense against diseases caused by micro-organisms, including viruses. Despite their small size, viruses have a huge impact on the host, as they produce substances that stimulate the antiviral response and affect it. The paper presents selected data on participation of immune system cells and their receptors in viral infections, as the host cells have evolved a number of specific cellular and humoral components of the signaling networks that are involved in the detection and the host's response to viral infections.

In Poland, rabbit is a highly valued animal, due to dietetic and flavour values of its meat, but above all, rabbits tend to be commonly used laboratory animals. The aim of the study was developing standards for counts of B-cells with CD19+ receptor, T-cells with CD5+ receptor, and their subpopulations, namely T-cells with CD4+, CD8+ and CD25+ receptor in the peripheral blood of mixed-breed Polish rabbits with addition of blood of meet breeds, including the assessment of the impact of four seasons of the year and animal sex on the values of the immunological parameters determined. The results showed that the counts of B- and T-cells and their subpopulations in peripheral blood remain within the following ranges: for CD19+ B-cells: 1.05 - 3.05%, for CD5+ T-cells: 34.00 - 43.07%, CD4+ T-cells: 23.52 - 33.23%, CD8+ T-cells: 12.55 - 17.30%, whereas for CD25+ T-cells: 0.72 - 2.81%. As it comes to the season of the year, it was observed that it principally affects the values of CD25+ T-cells, while in the case of rabbit sex, more changes were found in females.

The aim of the study was to develop reference values for such haematologic values as haemoglobin concentration, haematocrit value, volume of erythrocytes, thrombocytes, leucocytes, lymphocytes, neutrophils, basophils, eosinophils and monocytes in peripheral blood in Polish mixed-breed rabbits, considering the impact of the season (spring, summer, autumn, winter), and sex of the animals. The results reveal, that the season of the year has a small impact in Polish mixed-breed rabbits, and it principally referred to spring and summer. Finally it was shown, that sex has average impact on the studied values of haematological parameters.

Due to the lack of reference values for immunological parameters in Polish mixed breed rabbits, the study was aimed at developing standards for B-cells with CD19+ receptor, and T-cells with CD5+ receptor, and their subpopulations, namely T-cells with receptors CD4+, CD8+ and CD25+ in peripheral blood of Polish mixed breed rabbits, as well as at assessing the impact of four seasons and sex of the animals on such values. The results of the study not only are the source of reference values, but also revealed that the season of the year and sex of the rabbits affect the percentage of B- and T-cells and their subpopulations in peripheral blood.

Cell death is one of the processes that are currently extensively studied. Beside the commonly used terminology regarding cell death, i.e. apoptosis, autophagy, necrosis, and cornification, in recent years there has been a growing number of additional definitions of this process, such as mitotic catastrophe, anoikis, entosis, paraptosis, pyroptosis, pyronecrosis, excitotoxicity, and Wallerian degeneration, which are described in 2009 by the Nomenclature Committee on Cell Death as atypical. The recent report of that Committee significantly alter the classification and nomenclature of the cell death processes, in which excitotoxicity and Wallerian degeneration have not been taken into account. Thus the present review describes excitotoxicity, and Wallerian degeneration, as two processes associated to cell death phenomena characteristic for nervous system. Excitotoxicity is a neuronal death caused by excessive, or prolonged activation of receptors for the excitatory amino acids. Depending on the intensity of the initiating stimulus, the excitotoxicity may overlap with other types of cell death such as apoptosis and necrosis. Wallerian degeneration is a process that results when a nerve fiber is cut or crushed, in which the part of the axon separated from the neuron's cell body degenerates distal to the injury. Wallerian degeneration is not a typical cell death mechanism, since neurons undergoing this process remain alive.

The paper describes the characteristics, receptor profile and functions of T lymphocyte subpopulations (helper, cytotoxic, regulatory, memory and others). Among T helper cells one can enumerate Th0, Th1, Th2, Th9, Th17, Th22, T(FH) and nTh2, while T cytotoxic cells include Tc, NKT, Tγδ, and T CD8αα (IEL). Among regulatory cells there are nTreg, iTreg, T(R)1, and iT(R)35, as well as T lymphocytes with CD8, such as CD8+CD122+, CD8+CD28-, and CD11c+CD8+. And among memory T cells there are Tcm and Tem. Moreover, there are some so-called other T cells, such as Tn (T αβ CD4+ and T αβ CD8+), T exhausted and T anergic.

The objective of this study was to analyse the genetic variability and phylogenetic analysis of six strains of rabbit haemorrhagic disease virus (RHDV), including four Czech strains (CAMPV-351, CAMPV-561, CAMPV-562, CAMPV-558) and two French strains (Fr-1, Fr-2), on the basis of a fragment of the VP60 capsid structural protein-coding gene N-terminal region. The results of our own studies were compared to 26 RHDV strains obtained from GenBank. The analysis of the genetic variability of six RHDV strains indicated that the CAMPV-561 strain is the most genetically variable. Less variable were the Fr-1 and Fr-2 strains, while the least variable was CAMPV-351. In turn, the genetic distance among the six analysed strains and 26 strains obtained from GenBank was the greatest for CAMPV-351 and Whn/China [11.3 % according to the observed divergence (OD) method and 12.2 % according to the maximum likelihood (ML) method], while it was the lowest for CAMPV-351 and FRG (0.8 % in both the OD and ML methods). In turn, the scale of the genetic distances among the six analysed strains and five RHDVa strains (99-05, NY-01, Whn/China, Triptis, Iowa2000) ranged from 9.3-10.3 % in the OD method to 10.3-13.7 % in the ML method. The image of phylogenetic dependencies generated for the strains analysed and those obtained from GenBank revealed their distribution to be in five genetic groups (G1-G5), whereas the analysed strains were included in genetic groups 2 and 3.

This paper attempts to study the dynamics of apoptosis of granulocytes and lymphocytes in peripheral blood in rabbits infected with haemagglutinating (Vt97, Triptis, Hartmannsdorf) and non-haemagglutinating (Pv97, 9905 RHDVa) antigenic variants of the RHD virus. The pathogenicity of those antigenic variants was also assessed by recording the mortality of the infected animals. The animals were infected with antigenic variants and blood was sampled at hour 0, 4, 8, 12, 24, 36 p.i. and the percentage of apoptotic granulocytes and lymphocytes was measured with the use of flow cytometry. The results of the study showed that apoptosis is included during RHDV infection, as the number of apoptotic granulocytes and lymphocytes increases throughout the experiment; depending on the antigenic variant, apoptosis joins in at 4-8-12 h p.i. and lasts until 24-36 h p.i. Furthermore, the mortality of rabbits infected with the examined strains of RHD virus varied from 30% to 100%. This study performed for the first time in this manner, indicates the importance of apoptosis during infection with the RHD virus.