A new basis for the immunoregulatory activities of transfer factor--an arcane dialect in the language of cells

Discovery of Transfer Factors in Plant-Derived Proteins and an In Vitro Assessment of Their Immunological Activities

Repeated exposure to pathogens leads to evolutionary selection of adaptive traits. Many species transfer immunological memory to their offspring to counteract future immune challenges. Transfer factors such as those found in the colostrum are among the many mechanisms where transfer of immunologic memory from one generation to the next can be achieved for an enhanced immune response. Here, a library of 100 plants with high protein contents was screened to find plant-based proteins that behave like a transfer factor moiety to boost human immunity. Aqueous extracts from candidate plants were tested in a human peripheral blood mononuclear cell (PBMC) cytotoxicity assay using human cancerous lymphoblast cells-with K562 cells as a target and natural killer cells as an effector. Plant extracts that caused PBMCs to exhibit enhanced killing beyond the capability of the colostrum-based transfer factor were considered hits. Primary screening yielded an 11% hit rate. The protein contents of these hits were tested via a Bradford assay and Coomassie-stained SDS-PAGE, where three extracts were confirmed to have high protein contents. Plants with high protein contents underwent C18 column fractionation using methanol gradients followed by membrane ultrafiltration to isolate protein fractions with molecular weights of <3 kDa, 3-30 kDa, and >30 kDa. It was found that the 3-30 kDa and >30 kDa fractions had high activity in the PBMC cytotoxicity assay. The 3-30 kDa ultrafiltrates from the top two hits, seeds from Raphanus sativus and Brassica juncea, were then selected for protein identification by mass spectrometry. The majority of the proteins in the fractions were found to be seed storage proteins, with a low abundance of proteins involved in plant defense and stress response. These findings suggest that Raphanus sativus or Brassica juncea extracts could be considered for further characterization and immune functional exploration with a possibility of supplemental use to bolster recipients' immune response.

Characterization and Safety Profile of Transfer Factors Peptides, a Nutritional Supplement for Immune System Regulation

Imuno TF^® is a nutritional supplement composed of isolated transfer factors (TF) from porcine spleen. It is composed of a specific mixture of molecules that impact functions of the biological systems and historically is linked to the immune system regulation. In this study, we demonstrate for the first time its proteomic analysis, nutritional composition, and safety profile in terms of mutagenic potential and acute oral dose (LD₅₀). The obtained analysis indicated the product is a complex set of oligo- and polypeptides constituted of 163 different peptides which can potentially act on multiple mechanisms on the immune system pathways. The chemical composition showed low fat and low sugar content, saturated fatty acids-free, and the presence of 10 vitamins and 11 minerals. No mutagenic effect was observed, and the LD₅₀ was 5000 mg kg^-1 body weight. This accounts for a safe product to be used by the oral route, with potential benefits for the immune system.

Postulated Adjuvant Therapeutic Strategies for COVID-19

The number of COVID-19 patients is still growing exponentially worldwide due to the high transmissibility of the SARS-CoV-2 virus. Therapeutic agents currently under investigation are antiviral drugs, vaccines, and other adjuvants that could relieve symptoms or improve the healing process. In this review, twelve therapeutic agents that could play a role in prophylaxis or improvement of the COVID-19-associated symptoms (as add-on substances) are discussed. Agents were identified based on their known pharmacologic mechanism of action in viral and/or nonviral fields and are postulated to interact with one or more of the seven known mechanisms associated with the SARS-CoV-2 virus: (i) regulation of the immune system; (ii) virus entrance in the cell; (iii) virus replication; (iv) hyperinflammation; (v) oxidative stress; (vi) thrombosis; and (vii) endotheliitis. Selected agents were immune transfer factor (oligo- and polypeptides from porcine spleen, ultrafiltered at <10 kDa; Imuno TF®), anti-inflammatory natural blend (Uncaria tomentosa, Endopleura uchi and Haematoccocus pluvialis; Miodesin®), zinc, selenium, ascorbic acid, cholecalciferol, ferulic acid, spirulina, N-acetylcysteine, glucosamine sulfate potassium hydrochloride, trans-resveratrol, and maltodextrin-stabilized orthosilicic acid (SiliciuMax®). This review gives the scientific background on the hypothesis that these therapeutic agents can act in synergy in the prevention and improvement of COVID-19-associated symptoms.

Transfer Factor: Myths and Facts

Transfer factor (TF), also called "Lawrence transfer factor", or dialyzable leukocyte extract (DLE), has been used since the mid-twentieth century to transfer specific skin hypersensitivity through the injection of leukocytes from immunized donors to animals and humans. The main mechanism of action of TF has been suggested at the level of cell-mediated immunity, as it induces the production of migration inhibitory factor (MIF) and interferon gamma (IFN-γ). Otherwise, TF can inhibit nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB), and decrease tumoral necrosis factor α (TNF-α) and IL-4 levels. Given these biological effects, TF has been prescribed for a wide variety of conditions including infections, allergies, autoimmunity, and cancer, with inconsistent results. The exact nature of TF, however, remains unknown, so it has been impossible to accurately define its pharmacokinetics or dosage. This is further complicated because researchers have used TF in a variety of ways across the different studies: antigen-specific or non-antigen-specific, orally or subcutaneously administered, human and non-human origin. In this review we summarize the most important data about what TF is, its mechanism of action, how it is produced, its biological effects, and the available clinical trials using it, in order to establish its role and potential clinical applications in modern medicine.

In the Beginning was a Mutualism - On the Origin of Translation

The origin of translation is critical for understanding the evolution of life, including the origins of life. The canonical genetic code is one of the most dominant aspects of life on this planet, while the origin of heredity is one of the key evolutionary transitions in living world. Why the translation apparatus evolved is one of the enduring mysteries of molecular biology. Assuming the hypothesis, that during the emergence of life evolution had to first involve autocatalytic systems which only subsequently acquired the capacity of genetic heredity, we propose and discuss possible mechanisms, basic aspects of the emergence and subsequent molecular evolution of translation and ribosomes, as well as enzymes as we know them today. It is possible, in this sense, to view the ribosome as a digital-to-analogue information converter. The proposed mechanism is based on the abilities and tendencies of short RNA and polypeptides to fold and to catalyse biochemical reactions. The proposed mechanism is in concordance with the hypothesis of a possible chemical co-evolution of RNA and proteins in the origin of the genetic code or even more generally at the early evolution of life on Earth. The possible abundance and availability of monomers at prebiotic conditions are considered in the mechanism. The hypothesis that early polypeptides were folding on the RNA scaffold is also considered and mutualism in molecular evolutionary development of RNA and peptides is favoured.

New and cost effective cell-based assay for Dialyzed Leukocyte Extract (DLE)-induced Jurkat cells proliferation under azathioprine treatment

The human Dialyzed Leukocyte Extract (DLE) is a heterogeneous mix of oligopeptides of <10kDa, extracted from leukocytes of healthy donors. There is significant clinical evidence of improvement using DLE during treatment of allergies, cancer,immunodeficiencies, and in mycotic and viral infections. Nevertheless, the DLE exact nature and mechanism of action have been elusive for more than 50 years. DLE biological activity testing is necessary in DLE production and quality control. Both in vitro and in vivo assays exist: E-rosette test, induction of delayed type hypersensitivity in mice, leukocyte migration and IFN-γ secretion. The animal-origin materials and in vivo assays convey a considerable logistic, ethic and economic burden, meanwhile the available in vitro assays have been reported with limited reproducibility and sometimes contradictory results. Here we are reporting a new DLE biological activity cell-based assay. The A20 and Jurkat cell lines were treated with (+Aza) or without (-Aza) azathioprine, DLE (+DLE) or both (+Aza/+DLE). After 72h, the cell proliferation was analyzed by the MTT or BrdU incorporation assays. In +Aza/+DLE treated cells, we observed a significant higher proliferation, when compared with +Aza/-DLE. In the absence of Aza, cells did not present any proliferation difference between -DLE or +DLE treatments. Both assays, MTT and BrdU showed similar results, being the MTT test more cost effective and we select it for validation as DLE biological assay using Jurkat cells only. We tested three different lyophilized DLE batches and we found consistent results with acceptable assay reproducibility and linearity. The DLE capacity for rescuing Jurkat cell proliferation during +Aza treatment was consistent using different liquid and lyophilized DLE batches, presenting also consistent chromatographic profiles. Finally, DLE treatment in Jurkat cells did not result into significant IL-2 of IFN-γ secretion, and known lymphocyte proliferative drugs failed to rescue Jurkat cells viability in presence of +Aza, as +DLE treatment did in our MTT assay. In conclusion, our new cell-based MTT assay has excellent DLE biological activity consistency, robustness and is cost effective, presenting important advantages over previous DLE activity in vitro and in vivo assays.

[Transfer factors in medical therapy]

Transfer factor (TF) consists of messenger peptides produced by activated T lymphocytes as part of cellular immunity, and it acts in virgin lymphocytes through TF inducers, suppressors and specific antigens. TF is not immunogenic because it is not species-specific, since it contains a consensus sequence of amino acids LLYAQDL/VEDN. TF extracted from leukocytes can transfer immunity from a human to another species. TF extracts are complex, containing more than 200 molecules with molecular weights ranging from 1 to 20 kDa. The antigen specific transfer factors (STF) have molecular weights between 3,5 and 5 kDa. TF is easy to prepare and well tolerated. It does not contain HL-A antigens against potential receptors and it can used as adjuvant therapy in several diseases.

Ultrafiltered Pig Leukocyte Extract (UPLE, IMUNOR®) Potentiates Hematopoiesis–Stimulating Effects of G-CSFIn Vitroand Improves the Outcome of Treatment of Hematopoietic Radiation Damage in Mice with G-CSF

Ultrafiltered pig leukocyte extract (UPLE, Imunor), a heterogeneous mixture of low molecular weight (<10 kD) substances released from disintegrated pig leukocytes was tested from the point of view of its hematopoiesis-modulating activities using experiments in vitro and in vivo. Attention was focused especially on evaluation of the contingent ability of UPLE to potentiate the hematopoiesis-stimulating effects of recobinant human granulocyte colony-stimulating factor (G-CSF). Experiments in vitro revealed the capability of sera from mice administered UPLE perorally (p.o.) to stimulate proliferation of progenitor cells for granulocytes and macrophages (GM-CFC) in cultures of normal bone marrow cells. In addition, UPLE, as well as sera from mice given UPLE, added to the cultures in combination with G-CSF enhanced the numbers of GM-CFC significantly over those induced by sera after administration of either of the preparations alone. In in vivo experiments, UPLE was found to increase the counts of GM-CFC per femur and femoral bone marrow cellularity in sublethally irradiated mice when administered p.o. after irradiation in combination with G-CSF in comparison with the effects of G-CSF alone. These results indicate the possibility of using UPLE, a commercially available preparation, for treatment of hematopoietic suppression of various etiology.

The role of G-CSF and IL-6 in the granulopoiesis-stimulating activity of murine blood serum induced by perorally administered ultrafiltered pig leukocyte extract, IMUNOR®

IMUNOR, a low-molecular weight (< 12 kD) ultrafiltered pig leukocyte extract, has been previously found to have significant stimulatory effects on murine hematopoiesis supressed by ionizing radiation or cytotoxic drugs. This communication shows data on the mechanisms of these effects. Using ELISA assay, significantly increased levels of granulocyte colony-stimulating factor (G-CSF) and interleukin-6 (IL-6) were observed. On the contrary, no detectable levels of granulocyte-macrophage colony-stimulating factor (GM-CFC) and interleukin-3 (IL-3) have been found in blood serum of IMUNOR-treated mice. Incubation of the serum from IMUNOR-treated mice with antibodies against G-CSF caused abrogation of the ability of the sera to stimulate in vitro growth of colonies originating from granulocyte-macrophage progenitor cells (GM-CFC). In contrast, incubation of the serum with antibodies against IL-6 did not change its colony-stimulating activity. It may be inferred from these findings that G-CSF is probably the main cytokine responsible for the granulopoiesis-stimulating effects of IMUNOR. When the serum from IMUNOR-treated mice with G-CSF inactivated by anti-G-CSF antibodies (but with elevated IL-6) was added to cultures of bone marrow cells together with a suboptimum concentration of IL-3, a significant increase in the numbers of GM-CFC colonies was found. Moreover, conjoint inactivation of G-CSF and IL-6 significantly decreased the numbers of GM-CFC colonies in comparison with those observed when only G-CSF was inactivated. This observation strongly suggests that though IMUNOR-induced IL-6 is not able to induce the growth of GM-CFC colonies alone, it is able to potentiate the hematopoiesis-stimulating effect of IL-3. These findings represent a new knowledge concerning the hematopoiesis-stimulating action of IMUNOR, a promising immunomodulatory agent.

Bovine dialyzable leukocyte extract protects against LPS-induced, murine endotoxic shock

The pathophysiology of endotoxic shock is characterized by the activation of multiple pro-inflammatory genes and their products which initiate the inflammatory process. Endotoxic shock is a serious condition with high mortality. Bovine dialyzable leukocyte extract (bDLE) is a dialyzate of a heterogeneous mixture of low molecular weight substances released from disintegrated leukocytes of the blood or lymphoid tissue obtained from homogenized bovine spleen. bDLE is clinically effective for a broad spectrum of diseases. To determine whether bDLE improves survival and modulates the expression of pro-inflammatory cytokine genes in LPS-induced, murine endotoxic shock, Balb/C mice were treated with bDLE (1 U) after pretreatment with LPS (17 mg/kg). The bDLE improved survival (90%), suppressed IL-10 and IL-6, and decreased IL-1beta, TNF-alpha, and IL-12p40 mRNA expression; and decreased the production of IL-10 (P<0.01), TNF-alpha (P<0.01), and IL-6 (P<0.01) in LPS-induced, murine endotoxic shock. Our results demonstrate that bDLE leads to improved survival in LPS-induced endotoxic shock in mice, modulating the pro-inflammatory cytokine gene expression, suggesting that bDLE is an effective therapeutic agent for inflammatory illnesses associated with an unbalanced expression of pro-inflammatory cytokine genes such as in endotoxic shock, rheumatic arthritis and other diseases.

Hemopoiesis-stimulating effects and enhanced survival of irradiated mice after peroral or intraperitoneal administration of ultrafiltered pig leukocyte extract (UPLE, IMUNOR)

Ultrafiltered pig leukocyte extract (UPLE, IMUNOR, ImunomedicA, Ustí nad Labem, Czech Republic) administered perorally (p.o.) or intraperitoneally (i.p.) enhanced recovery of the pool of granulocyte-macrophage hemopoietic progenitor cells (GM-CFC) in the bone marrow of normal or sublethally irradiated mice and increased survival of mice exposed to a lethal radiation dose. In experiments in vitro, sera of mice treated with UPLE p.o. or i.p. induced GM-CFC colony formation in cultures of normal mouse bone marrow cells, i.e., produced colony-stimulating activity (CSA). UPLE alone did not induce GM-CFC colony growth, i.e., had no CSA. When UPLE alone or sera of mice administered UPLE p.o. or i.p. were added to bone marrow cultures containing suboptimal concentration of recombinant mouse interleukin-3 (rmIL-3), both UPLE and the sera increased the counts of GM-CFC colonies in comparison with cultures containing only rmIL-3, i.e., produced co-stimulating activity (CoSA). Based on the findings obtained in vitro, it can be hypothesized that the described CSA and CoSA of UPLE may play a role also under in vivo conditions; enhancement of the recovery of hemopoiesis suppressed by ionizing radiation may be due to co-operation of the stimulatory effects of UPLE with the action of cytokines endogenously produced in irradiated tissues.

Positive effects of dialyzable leukocyte extract (DLE) on recovery of mouse haemopoiesis suppressed by ionizing radiation and on proliferation of haemopoietic progenitor cells in vitro

Dialyzed leukocyte extract (DLE) (Immodin SEVAC, Czech Republic) was shown to enhance the recovery of the pools of hemopoietic stem cells (CFUs) and of granulocyte-macrophage hemopoietic progenitor cells (GM-CFC) in the bone marrow in vivo, as well as to increase the numbers of leukocytes and thrombocytes in the peripheral blood of mice exposed to a sublethal dose of gamma-rays, with an ensuing increase in the numbers of mice surviving the lethal radiation dose. In experiments performed in vitro, DLE or sera of mice administered with DLE were added to cultures of intact mouse bone marrow cells containing suboptimal concentrations of hemopoietic stimulatory cytokines, namely recombinant mouse interleukin-3 (rmIL-3) or recombinant mouse granulocyte-macrophage colony-stimulating factor (rmGM-CSF); under these experimental conditions, both DLE and sera of mice administered DLE were found to increase the counts of GM-CFC colonies in the cultures. It can be hypothesized on the basis of the findings obtained in vitro that the described co-stimulating activity (CoSA) of DLE may play a role also under in vivo conditions; the enhancement of the recovery of hemopoiesis suppressed by ionizing radiation may be due to a co-operation of the stimulatory effects of DLE with the action of cytokines endogenously produced in irradiated tissues.

Transfer factor in the age of molecular biology: a review

Current data suggests that the transferring of immunologically specific information by transfer factor molecules requires interaction with a cell that has been genetically programmed to be antigen reactive but at the time of interaction is unprimed. Contact with transfer factor molecules would allow a naive recipient, on a first encounter with antigen, to make a secondary rather than a primary immunological response. Transfer factor molecules for each and every antigenic determinant are thus necessary. Transfer factors made from animals or humans are capable of transferring antigen specificity across a species barrier. Even primitive species have cells from which one can make transfer factors. The molecules are, therefore, well conserved and it is reasonable to suggest that they are important for normal immunological functioning. Proposed mechanisms of action must explain the fact that transfer factors obtained from the cells of high responder animals are capable of transferring delayed hypersensitivity to low responder animals while the reverse is not true. Transfer factor molecules are likely to interact with the variable regions of the alpha and/or beta chain of T cell receptors to change their avidity and affinity for antigen in a way that otherwise would only occur after an encounter with antigen.

Dialyzable lymphoid extract (DLE) from mice resistant to STZ-induced diabetogenesis can interrupt the progress of diabetes in STZ-treated CD-1 mice

DLE was prepared from the minority of euglycemic CD-1 mice, previously injected with STZ, and was administered to hyperglycemic CD-1 male mice 1, 2 and 3 weeks after completion of multidose STZ. Mice treated with DLE derived from 2 x 10(7) (IX) or 10(8) lymphocyte equivalents (lymph.equ) were significantly less hyperglycemic than the saline treated controls (P < 0.001). The effects of DLE remained evident for more than 10 weeks after the final DLE treatment. Mice treated with DLE prepared from diabetic mice (hg DLE) developed a somewhat more rapid onset of hyperglycemia than the STZ treated control animals, although this effect did not achieve statistical significance (P = 0.1). This DLE was absorbed on a rat insulinoma cell line (RIN), which contains interspecies cross-reacting islet antigens, and compared to the unabsorbed DLE. Mice treated with hg DLE preabsorbed on RIN cells, showed a slower onset of hyperglycemia. DLE prepared from euglycemia mice and the RIN-absorbed fraction were equally capable of preventing hyperglycemia (P < 0.05). In order to determine whether the DLE effects were genetically restricted, DLE was prepared from BALB/c mice, normally resistant to the diabetogenic effects of multidose STZ, both before and after STZ treatment. STZ primed CD-1 mice treated with 3 weekly doses of 2 x 10(7) lymph. equ. of untreated BALB/c derived DLE, STZ treated BALB/c derived DLE, and STZ treated CD-1 DLE were all less hyperglycemic than the control mice, who received saline (P < 0.001). However, mice treated with CD-1 DLE were less hyperglycemic than the mice given BALB/c derived DLE (P < 0.05). These effects were relatively long-lived. Mice that were given the > 3,500 Dalton fraction of CD-1 DLE were significantly less hyperglycemic than either the control mice or those treated with the < 3,500 Dalton fraction of CD-1 DLE (P < 0.05). Effects remained evident for more than 3 months after the last dose of DLE. Pancreatic tissue from the mice treated with the > 3,500 Dalton fraction of CD-1 derived DLE revealed slightly more islets of a slightly greater size with less surrounding inflammation than either control mice or mice treated with the < 3,500 Dalton fraction of DLE.

Transfer factor--current status and future prospects

We have detected new clues to the composition and function of "Transfer Factor" using the direct Leucocyte Migration Inhibition (LMI) test as an in vitro assay of Dialysates of Leucocyte Extracts (DLE). This approach has revealed two opposing antigen-specific activities to be present in the same > 3500 < 12,000 DA dialysis fraction - one activity is possessed of Inducer/Helper function (Inducer Factor). The opposing activity is possessed of Suppressor function (Suppressor Factor). When non-immune leucocyte populations are cultured with Inducer Factor they acquire the capacity to respond to specific antigen and inhibition of migration occurs. This conversion to reactivity is antigen-specific and dose-dependent. When immune leucocyte populations are cultured with Suppressor Factor their response to specific antigen is blocked and Inhibition of Migration is prevented.

Effect of Brucella abortus transfer factor in preventing murine brucellosis

Mice vaccinated with a protein extract of attenuated Brucella abortus strain 19 had increased resistance to infection with virulent B. abortus strain 2308 and had increased antibody responses to strain 2308. However, resistance to infection and antibody responses were not increased when nonvaccinated recipient mice were given transfer factor preparations that were obtained from either vaccinated donor mice or strain 2308-infected donor mice. Vaccination of mice with the strain 19 extract plus treatment with each transfer factor preparation also did not further increase resistance to infection or antibody responses when compared with mice that received the vaccine alone. These results suggest that transfer factor from mice that have either vaccine-induced protective immunity to B. abortus or active B. abortus infections does not enhance antibody responses and resistance to infection with B. abortus.

Murine transfer factor. IV. Studies with genetically regulated immune responses

Transfer factor-containing dialysates from mice that were either high or low responders to GAT10, GLA5, or ovalbumin were assayed for their ability to transfer delayed hypersensitivity to murine recipients of either high or low responder phenotype. Dialysates from high responder strains contained transfer factor that would transfer delayed hypersensitivity to both high and low responder recipients. These transfers were not restricted by disparities at the MHC or Igh loci. Identically prepared materials from low responder donors contained little or no transfer factor activity and would not transfer delayed hypersensitivity to either high or low responder recipients. Thus, administration of transfer factor transfers the high responder phenotype to low responder recipients. The data also suggest that production of transfer factor is regulated by Ir genes but that the immunologic activities of transfer factor are not.

A randomized, double-blind, placebo-controlled trial of transfer factor as adjuvant therapy for malignant melanoma

One hundred and sixty-eight evaluable patients participated in a randomized, double-blind study of transfer factor (TF) versus placebo as surgical adjuvant therapy of Stage I and Stage II malignant melanoma. Eighty-five patients received TF prepared from the leukocytes of healthy volunteer donors; eighty-three participants received placebo. Therapy was initiated within 90 days of resection of all evident tumor and continued until 2 years of disease-free survival or the occurrence of unresectable dissemination of melanoma. Known prognostic variables were similarly distributed in the treatment and control groups, documenting the randomization efficacy. Three endpoints were analyzed: disease-free interval, time to Stage III metastasis, and survival. After a median follow-up period of 24.75 months, there was a trend in favor of the placebo group with regard to all three endpoints and this was significant (P less than or equal to 0.05) for time to Stage III metastasis. These findings indicate that TF is not effective as surgical adjuvant therapy of malignant melanoma.

A soluble suppressor T cell factor protects against experimental intraabdominal abscesses

This paper describes a suppressor T cell factor which protects mice against intraabdominal abscesses caused by Bacteroides fragilis. This soluble cell-free factor (ITF) is derived from splenic T cells from mice immunized with capsular polysaccharide (CP) of B. fragilis. Mice receiving ITF are protected from developing abscesses caused by B. fragilis to the same degree as animals receiving intact immune splenic T cells. The factor appears to be small in molecular size as protective activity is dialyzable through a 12,000-mol wt exclusion dialysis membrane and is present in fractions intermediate between the bed and void volumes of a P2 Biogel column. The protective effect of ITF is antigen-specific to B. fragilis alone. Mice given a complex inoculum of B. fragilis, enterococcus, and another anaerobe develop abscesses even after receiving column-purified ITF. The activity of ITF also is eliminated after adsorption with B. fragilis CP coupled to sheep erythrocytes but not with an unrelated CP coupled to sheep erythrocytes. ITF, therefore, appears to have a binding site for B. fragilis CP. ITF is heat-labile and loses efficacy after protease digestion, suggesting that the active material is a protein. These studies define a suppressor cell factor with activity in a model system resembling human disease and offer promise for increased understanding of the diversity of cell-mediated immune systems.