Influence of perinatal stress on the hormone content in immune cells of adult rats: dominance of ACTH.

Rat dams were stressed by total deprivation of food and water for 48 h just before or directly after delivery and the offspring were studied when adult. The immune cells' hormone content (ACTH, histamine, serotonin, and T(3)) was measured by immunocytochemical flow cytometry. The elevation of ACTH content in males was convincing in each cell type (lymphocytes, monocytes and granulocytes, and mast cells). The change in histamine and T(3) content was inconsistent, while serotonin level did not change at all. As ACTH is the key hormone in the General Adaptation Syndrome, it seems likely that the perinatal stress primarily caused elevation in ACTH level and it was provoking the life-long hormonal imprinting. There was a difference between the reaction of males and females (with males' advance), which points to the gender dependence of the phenomenon. It is important that the effect of stress on the offspring was similar in case of direct (prenatal, in the mother) and indirect (postnatal, transmitted by milk) stress treatment, which calls attention to the danger of stress during this latter period.

Thyrotropic hormone (TSH) regulation of triiodothyronine (T(3)) concentration in immune cells.

OBJECTIVE: Cells of the immune system (peritoneal lymphocytes, monocytes, granulocytes and mast cells as well as thymocytes) contain triiodothyronine (T(3)). The aim of the present experiments was to study whether thyrotropic hormone (TSH) regulates or not the T(3) concentration of these cells. METHODS: Peritoneal fluid and thymus cells of adult rats were studied by immunocytochemistry, combined with flow cytometry for triiodothyronine content with or without in-vitro TSH treatment. In addition, adult female CD1 mice were treated in vivo with 10 or 40 mU TSH and after 1 hour peritoneal immune cells were studied using the above mentioned method. RESULTS: Both in vitro (in rat) and in vivo (in mice) TSH treatments significantly elevated the T(3) content in each cell type. In vitro TSH 0.1 mU/ml cell suspension was enough to provoke about 50 % increase in T(3) production. CONCLUSION: T(3) concentration in immune cells seems to be regulated by TSH, similarly to the T(3) in the thyroid. Considering the large number of immune cells in an organism, TSH regulation of their T(3) content could have an important physiological and pathological role, both in and beyond the immune system.

Highlights of a new type of intercellular communication: microvesicle-based information transfer.

Microvesicles (MVs) are membrane-covered cell fragments released by most cell types during apoptosis or activation. They are increasingly considered to play a pivotal role in information transfer between cells. Their presence and role have been proven in several physiological and pathological processes, such as immune modulation in inflammation and pregnancy, or blood coagulation and cancer. MVs represent a newly recognized system of intercellular communications. They not only may serve as prognostic markers in different diseases, but could also hold the potential to be new therapeutic targets or drug delivery systems. The present overview aims to highlight some aspects of this new means of cellular communication: "microvesicular communication".

T lymphocytes are targets for platelet- and trophoblast-derived microvesicles during pregnancy.

Microvesicles (MVs) can derive from several cell types and their membranes contain cell surface elements. Their role is increasingly recognized in cell-to-cell communication, as they act as both paracrine and remote messengers, occurring in circulating form as well as in plasma. Successful pregnancy requires a series of interactions between the maternal immune system and the implanted fetus, such that the semi-allograft will not be rejected. These interactions occur at the materno-placental interface and/or at a systemic level. In the present study we identified for the first time the in vivo plasma pattern of the MVs of third-trimester, healthy pregnant women, their cellular origin, and their target cells using flow cytometry and confocal laser microscopy. We searched for the cellular target molecules of thrombocyte-derived MVs with the help of neutralizing antibodies. We examined the in vitro effects of MVs on STAT3 phosphorylation of primary lymphocytes and Jurkat cells. We found that both placental trophoblast-derived and maternal thrombocyte-derived MVs bind to circulating peripheral T lymphocytes, but not to B lymphocytes or NK cells. We were able to show that the P-selectin (CD62P)-PSGL-1 (CD162) interaction is one mechanism binding platelet-derived MVs to T cells. We were also able to demonstrate that MV-lymphocyte interactions induce STAT3 phosphorylation in T cells. Our findings indicate that both thrombocyte- and trophoblast-derived MVs may play an important role in the immunomodulation of pregnancy. We suggest that the transfer of different signals via MVs represents a novel form of communication between the placenta and the maternal immune system, and that MVs contribute to the establishment of stable immune tolerance to the semi-allograft fetus.

Effects of sodium fluoride (NaF) on the cilia and microtubular system of Tetrahymena.

The effect of the nucleophilic reagent NaF on the microtubular system of Tetrahymena was studied by using scanning electron microscopy (SEM), confocal microscopy, and flow cytometry. Treatments with 40 mM NaF significantly reduced the amount of alpha-tubulin while 80 mM treatment did not alter its quantity. One possible explanation for this alpha-tubulin overexpression is that the higher amount of alpha-tubulin enables this organism to carry out the appropriate function of the cytoskeleton under this undesirable influence of higher amounts of 80 nM NaF. However, the amount of acetylated tubulin increased in a dose-dependent manner. The cilia became fragile under the effect of 80 mM NaF. Confocal microscopy revealed that after 40 mM NaF treatment transversal microtubule bands (TMs) and longitudinal microtubule bands (LMs) as well as basal bodies (BBs) were extremely strong decorated with anti-acetylated tubulin antibody and TM-localization abnormalities were visible. In the 80 mM NaF-treated cells, the deep fiber of oral apparatus was very strongly labeled, while the TMs and LMs were less decorated with anti-acetylated tubulin antibody, and LM deformities were visible. It is supposed that post-translational tubulin modifications (e.g., acetylation) defend the microtubules against the NaF-induced injury. NaF is able to influence the activity of several enzymes and G-proteins, therefore is capable to alter the structure, metabolism, and the dynamics of microtubular system. The possible connection of signaling and cytoskeletal system in Tetrahymena is discussed.

Histamine regulates placental cytokine expression--in vivo study on HDC knockout mice.

Successful pregnancy is closely related to polarization toward a Th2 type immune response. As histamine is known to initiate Th2 dominance during inflammatory processes we raised the question whether histamine has any effect on the actual tuning of proper cytokine balance for the proceeding of the gestation. Histamine has multiple functions in the process of pregnancy, different studies have shown the direct and/or indirect presence of histamine action in the placenta as well. As HDC is the unique histamine producing enzyme in eukaryotes, we used HDC (so endogenous histamine)-deficient knockout mice as reliable model for studying histamine-related processes in vivo. We examined the placental histamine content and the expression of histamine receptors and Th1/Th2/Th3 type cytokines in the placenta. We showed for the first time the influence of histamine on the orchestrated regulation of placental cytokine expression. In the absence of local histamine the cytokine balance is shifted toward Th1 types at the maternal-placental interface, threatening pregnancy. We also measured splenic lymphocyte subpopulation ratios in pregnant and non-pregnant mice and found that in pregnancy they are independent of the presence of histamine.

Monocyte activation drives preservation of membrane thiols by promoting release of oxidised membrane moieties via extracellular vesicles.

The redox state of cellular exofacial molecules is reflected by the amount of available thiols. Furthermore, surface thiols can be considered as indicators of immune cell activation. One group of thiol containing proteins, peroxiredoxins, in particular, have been associated with inflammation. In this study, we assessed surface thiols of the U937 and Thp1 monocyte cell lines and primary monocytes in vitro upon inflammatory stimulation by irreversibly labelling the cells with a fluorescent derivative of maleimide. We also investigated exofacial thiols on circulating blood mononuclear cells in patients with rheumatoid arthritis and healthy controls. When analysing extracellular vesicles, we combined thiol labelling with the use of antibodies to specific CD markers to exclude extracellular vesicle mimicking signals from thiol containing protein aggregates. Furthermore, differential detergent lysis was applied to confirm the vesicular nature of the detected extracellular events in blood plasma. We found an increase in exofacial thiols on monocytes upon in vitro stimulation by LPS or TNF, both in primary monocytes and monocytic cell lines (p<0.0005). At the same time, newly released extracellular vesicles showed a decrease in their exofacial thiols compared with those from unstimulated cells (p<0.05). We also found a significant elevation of surface thiols on circulating monocytes in rheumatoid arthritis patients (p<0.05) and newly released extracellular vesicles of isolated CD14+ cells from rheumatoid arthritis patients had decreased thiol levels compared with healthy subjects (p<0.01). Exofacial peroxiredoxin 1 was demonstrated on the surface of primary and cultured monocytes, and the number of peroxiredoxin 1 positive extracellular vesicles was increased in rheumatoid arthritis blood plasma (p<0.05). Furthermore, an overoxidised form of peroxiredoxin was detected in extracellular vesicle-enriched preparations from blood plasma. Our data show that cell surface thiols play a protective role and reflect oxidative stress resistance state in activated immune cells. Furthermore, they support a role of extracellular vesicles in the redox regulation of human monocytes, possibly representing an antioxidant mechanism.

Histidine decarboxylase expression in human melanoma.

Histamine has been implicated as one of the mediators involved in regulation of proliferation in both normal and neoplastic tissues. Histidine decarboxylase, the only enzyme that catalyzes the formation of histamine from L-histidine, is an essential regulator of histamine levels. In this study, we investigated the gene and protein expression of histidine decarboxylase in melanoma. Reverse transcriptase polymerase chain reaction and in situ hybridization studies of WM-35, WM-983/B, HT-168, and M1 human melanoma cell lines both resulted in positive signals for histidine decarboxylase messenger RNA. A polyclonal chicken antibody was developed against human histidine decarboxylase and protein expression was confirmed by western blot analysis of the cell lysates, revealing a predominant immunoreactive band at approximately 54 kDa corresponding to monomeric histidine decarboxylase. Protein expression of histidine decarboxylase was also shown by flow cytometric analysis and strong punctate cytoplasmic staining of melanoma cell lines. Moreover, both primary and metastatic human melanoma tissues were brightly stained for histidine decarboxylase. When compared with the very weak or no reactions on cultivated human melanocytes both western blot and immunohistochemical studies showed much stronger histidine decarboxylase expression in melanoma cells. These findings suggest that expression of histidine decarboxylase is elevated in human melanoma.

Effect of alpha-FMH and DPPE on colony-forming properties of human peripheral progenitor cells.

Endogenous histamine regulates the haematopoiesis. Histidine decarboxylase inhibitor decreases the histamine level, and its intracellular antagonist decreases the histamine effect. The effect of histidine decarboxylase inhibitor (alpha-fluoromethyl histidine) and the intracellular antagonist of histamine [N'N-diethyl-2-4-(phenylmethyl) phenoxyethan-amine-HCl] was investigated on the colony-forming ability of human peripheral progenitor cells. Semi-solid culture medium was used both in the presence and in the absence of 3 U/ml erythropoietin. alpha-Fluoromethyl histidine was used in the range of 50 through 150 micro Mol/ml, the concentration of N'N-diethyl-2-4-(phenylmethyl) phenoxyethanamine-HCl was between 5 and 25 micro Mol/ml. The number of both the erythroide and the granulocyte macrophage colony was significantly decreased in a concentration dependent manner by the presence of both N'N-diethyl-2-4-(phenylmethyl) phenoxyethanamine-HCl (in all concentrations used) and &alpha-fluoromethyl histidine (at higher concentration). The inhibitory effect was decreased by erythropoietin.

Microheterogeneity of the cell surface tyrosine phosphatase, CD45RA, on T cells: phytohaemagglutinin binding and non-binding fraction of the 220 kDa isoform.

The CD45 antigen is a family of the transmembrane tyrosine phosphatases expressed on cells of haemopoietic origin. The molecules are distinguished by the different aminoacid sequence and glycosylation on the N terminus. Although all isoforms are heavily glycosylated and exert receptor like structures on the extracellular part, the role of the glycosylation in the possible receptor function and the ligand of the CD45 has not been determined yet. In this study we have examined the binding of phytohaemagglutinin (PHA) to the different isoforms and its relation to the phosphatase activity. Immunoblotting experiments revealed that the 220 kDa form of the CD45RA contained a PHA binding fraction when immunoprecipitated with CD45RA monoclonal antibody (mAb), while an isoform with identical molecular mass immunoprecipitated by anti-CD45 did not bind PHA. We concluded that the 220 kDa form was heterogeneous with respect to PHA binding. Functional data also confirmed this heterogeneity: previous extraction of the PHA binding proteins resulted in the elimination of all the phosphatase activity from CD45, while only a part of that was removed from CD45RA immunoprecipitates.

Inhibition of effects of endogenously synthesized histamine disturbs in vitro human dendritic cell differentiation.

Histamine, a principal mediator in various physiological and pathological cell functions is synthesized from L-histidine exclusively by histidine decarboxylase, an enzyme, which is expressed in many tissues of mammalian organism. Histamine plays a role in various cellular functions, including cell differentiation. The aim of this study was to determine the presence and to characterize the role of the endogenously produced histamine during in vitro dendritic cell (DC) differentiation induced by interleukin-4 (IL-4) and granulocyte-monocyte colony stimulating factor (GM-CSF). The changes in intracellular histamine content, biosynthesis and gene expression of histidine decarboxylase were investigated during this process. One also studied how histamine receptor antagonists and a histamine synthesis blocker influence the expression of differentiation antigens on the DC during in vitro maturation. During in vitro differentiation parallel culture incubations were performed by adding H1 receptor antagonist triprolidine, H2 receptor antagonist tiotidine, the tamoxifene derivate DPPE which blocks the intracellular binding of histamine, and an irreversible blocker of histidine decarboxylase, alpha-fluoromethyl histamine (alpha-FMH). The results show simultaneous increase in both histidine decarboxylase level and histamine content during differentiation of elutriated monocytes toward DC. Both blockade of de novo histamine production (by alpha-FMH) and inhibition of histamine binding (by H1 and H2 receptor antagonists, triprolidine and tiotidine, respectively) markedly decreased CD40 expression and that of CD45 from the 3rd day of treatment. DPPE by disturbing intracellular interaction of histamine with cytochrome P-450 moieties was able to decrease the expression of CD45, CD86, HLA-DR, CD33, CD40 and CD11c. Based on the data it is suggested that endogenous histamine is actively synthesized during cytokine-induced in vitro DC differentiation. The functional relevance and autocrine and paracrine action of endogenously produced histamine is supported by the data showing that inhibition of histamine synthesis by HDC, blocking of histamine binding by both 'extracellular' histamine receptors (by specific antagonists, triprolidine and tiotidine) and 'intracellular' antagonists (DPPE) disturb the differentiation of DC. This conclusion is supported by the fact, that by the inhibition of histamine acting in an autocrine/paracrine way, the expression pattern of differentiation markers on DC is markedly changed.

Soluble interleukin-6 receptor (sIL-6R) makes IL-6R negative T cell line respond to IL-6; it inhibits TNF production.

The receptor for interleukin-6 (IL-6) consists of two subunits: a ligand specific IL-6Ralpha and gp130 that is responsible for signal-transduction. A soluble form of the ligand specific chain was described that when complexed to IL-6 is capable of binding to the membrane-bound gp130 subunit and thus can elicit signal-transduction. This soluble receptor can act on cells that express only the gp130 but not the ligand-specific subunit of the IL-6R. This phenomenon, called trans-signaling, introduced a novel aspect of cytokine action. In this study we examined the response of Jurkat cells, that are known not to express IL-6Ralpha, to IL-6, the soluble IL-6 receptor (sIL-6R) and a covalent complex of IL-6 and sIL-6R termed Hyper-IL-6. We studied the expression of tumour necrosis factor (TNF) and interferon-gamma (IFN-gamma). The complex of IL-6+sIL-6R and Hyper-IL-6 inhibited significantly the production of TNF in a gp130-dependent manner, whereas no differences in IFN-gamma expression were found. IL-6 and sIL-6R alone were not effective. Because we did not detect major differences in the TNF mRNA levels upon treatments, we conclude that the inhibition of TNF production should occur at the post-transcriptional level. These results provide another example of trans-signaling and underline the physiological importance of sIL-6R, and in the case of Hyper-IL-6 its possible therapeutic application can also be considered.

Measurement of intracellular interferon-gamma and interleukin-4 in whole blood T lymphocytes from patients with systemic lupus erythematosus.

Contradictory data are available about the dominance of T-helper 1 (T(H)1), or T-helper 2 (T(H)2) cytokines in systemic lupus erythematosus (SLE). Therefore, intracellular interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) production of T lymphocytes was measured in whole blood of healthy donors and active and inactive SLE patients by flow cytometry. The percentage of IFN-gamma and IL-4 positive cells was low (<1%) in unstimulated samples of the healthy controls, while that of IFN-gamma and IL-4 positive cells in the stimulated cells was 25.2+/-10.6% and 0.6+/-1.5%, respectively. No significant difference was found between SLE patients and healthy controls and between active and inactive patients in these parameters either in the unstimulated or in the stimulated samples. One patient with severe disease had as high as 11.8% IL-4 positive cells and 12.5% IFN-gamma positive cells in the stimulated samples, but after the initiation of intensive corticosteroid and cytostatic therapy, the percentage of IL-4 positive T cells decreased (4.76%) while that of IFN-gamma positive T cells increased (47.91%). We conclude that the intracellular IL-4 and IFN-gamma expression of T lymphocytes does not differ markedly between SLE patients and healthy controls, with the possible exception of severe disease, when marked IL-4 overproduction may exist beside low IFN-gamma production. Furthermore, corticosteroid and cytostatic therapy might normalize this altered IFN-gamma/IL-4 ratio.

Multi-color analysis of monocyte and dendritic cell precursor heterogeneity in whole blood.

The coexpression analysis of the 55-kDa lipopolysaccharide receptor (CD14) and the Fc gamma-receptor III (CD16) reveals a broad heterogeneity of blood monocytes which in our previous work could be divided into five subpopulations based on correlated differences in expression of the pan-myeloid antigen CD33 and the adhesion antigens CD11a, CD11b and CD56. An even larger complexity of myeloid cells with antigen presenting capacity in peripheral blood is suggested by the description of small populations of immature and mature precursors of dendritic cells which rapidly develop potent costimulatory activity and a dendritic morphology in in vitro culture. The identity of the subsets of cells which have been described based on heterogeneous analytical approaches, however, remains unclear. The goal of this study, therefore, was the correlated analysis of monocyte subpopulations and dendritic cell precursors in a quantitative whole blood assay. This was achieved based on simultaneous expression analysis of the monocyte markers CD14 and CD16 with antigens such as CD33, HLA-DR, the integrin CD11c, and the interleukin-3 receptor alpha-chain (CD123) which in absence of lineage-related antigens have been used for description of dendritic cell precursors. The selected marker panel revealed identity of cells previously described as CD33bright CD14dim dendritic cell precursors with CD11c+lin-HLA-DR+ cells. Dendritic cell precursors considered to be less mature which have been alternatively described as CD33+ CD14dim CD16- cells or CD123hi dendritic cell precursors, however, were shown to differ in phenotype from each other with regard to expression density of CD33 and expression of CD14. In summary, our study revealed a complex heterogeneity of monocytes and dendritic cell precursors in peripheral blood and indicates that a direct comparison of the analytical approaches of different authors is needed to further clarify the ontogeny of human monocytes and dendritic cells.

Retinoic acid enhances histamine content and H1 receptor expression in human neuroblastoma cell line Paju.

BACKGROUND: A human neuroblastoma cell line (Paju) was induced by retinoic acid (RA) to differentiate into neuron-like cells. MATERIALS AND METHODS: We studied the expression and the possible role of histamine receptors H1 and H2 in retinoic-acid mediated differentiation by semiquantitative RT-PCR. We studied the effect of exogeneously added RA on the morphological change of the human neuroblastoma cell line and the differentiation was followed by vimentine, glial fibrillary acidic protein (GFAP) and neurofilament (NF) immunostaining. We monitored the change of the histidine decarboxylase (HDC) expression and the histamine content during the RA treatment by immunoblot and flow cytometry methods. RESULTS: Our data showed that H1 and H2 histamine receptors are present on Paju cells. Ten nM RA markedly increased the H1 receptor expression of these cells, while the H2 expression was unchanged. CONCLUSION: In the RA-treated Paju cells, the histamine content increased compared to the untreated cells, suggesting that neuroblastoma-derived histamine is involved in the regulation of RA-induced in vitro differentiation by H1 receptors.

Time course of leukocyte response and free radical release in an early reperfusion injury of the superior mesenteric artery.

The sequence of changes in circulating immune cells and in free radical production was studied during the small intestine reperfusion. Rat small intestine ischemia/reperfusion was induced by a 45 min superior mesenteric artery occlusion followed by a 4-hour reperfusion. Samples of peripheral blood were collected every 20 min during reperfusion. While the number of polymorphonuclear leukocytes increased significantly both in the sham-operated controls and the experimental group (about 400 per cent at the end of reperfusion), a decrease in lymphocyte counts to 60 per cent was observed in the experimental group only. Although there were no changes in the counts of total T lymphocytes, a significant reduction in B cell counts was observed. Flow-cytometrical measurements showed no changes in the Tc subpopulation, while the Th subpopulation increased in the experimental group only. Free radical generation in blood (luminometric measurements) increased gradually and reached an eight-fold level by the end of reperfusion in both groups. Thus, it has been shown that the increase in free radical production is mainly due to the increased number of polymorphonuclear leukocytes mobilized already at the initial stages of reperfusion. The reduction in B lymphocyte population is probably due to homing mechanisms

Is there a possibility of intrasystem regulation by hormones produced by the immune cells? Experiments with extremely low concentrations of histamine.

The effect of histamine in 10 -9 , 10 -12 , 10 -15 and 10 -18 molar concentrations was studied on the beta-endorphin and triiodothyronine (T 3 ) content of peritoneal immune cells (lymphocytes, monocyte-granulocyte group and mast cells), using immunocytochemical flow cytometric method. The lower concentrations (10 -15 and 10 -18 M) were effective, where endorphin content was significantly lowered and T 3 content was significantly elevated. The results call attention to the extreme sensitivity of histamine receptors in this hormonal index and to the specific response by hormone production to histamine, in the immune cells. The new data support the earlier hypothesis, that there is a hormonal network inside the immune system.

Gender dependence in the hormone content of the immune cells.

Adrenocorticotropic hormone (ACTH), endorphin, progesterone and triiodothyronine (T3) content of immune cells (lymphocytes, monocyte-macrophage-granulocyte group and mast cells of peritoneal fluid, blood lymphocytes and thymic lymphocytes) was studied by immunocytochemistry and flow cytometric analysis and compared in young (four weeks old) and sexually matured (two and a half months old) male and female rats. In most of cases, cells of female animals contained significantly more hormones, however, in the young group ACTH content of blood lymphocytes was double in males than that of females. In adults only T3 content of mast cells was higher in males. Progesterone was present only in the cells of the young group. The results show that i) hormone content in the immune cells is gender-dependent with the adventage of females and ii) this difference is not influenced by the sexual maturation.

Effects of different fixatives on demonstrating epinephrine and ACTH hormones in Tetrahymena.

The unicellular Tetrahymena produces, contains, and secretes many hormones characteristic of higher animals. We tested three fixatives, formaldehyde, N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDAC), and glutaraldehyde for suitability for immunocytochemical demonstration of epinephrine and adrenocorticotropic harmone (ACTH) in Tetrahymena. Using flow cytometric immunocytochemistry, staining of ACTH was highest after EDAC fixation and that of epinephrine after glutaraldehyde fixation. Using laser scanning confocal microscopy, formaldehyde fixation prevented staining. Glutaraldehyde fixation produced high autofluorescence, which obscured specific staining. After EDAC fixation, ACTH was localized in the ciliary row; however, demonstration of epinephrine was not improved. Our results show that there is no "fixative for any hormone." Different fixatives are needed to demonstrate different hormones in Tetrahymena.

Presence and distribution of biogenic amines (histamine, serotonin and epinephrine) in immunophenotyped human immune cells.

OBJECTIVE: In animal experiments many hormones were demonstrated in immune cells. However, very few data are at our disposal in the case of human immune cells. In an earlier experiment, ACTH, endorphin and T(3) were studied and found in different subsets of human immune cells. Here, three biogenic amines (histamine, serotonin and epinephrine) were studied. METHODS: Biogenic amine content of immunophenotyped human lymphocytes from 15 blood donors were investigated by multicolor flow cytometry using anti-biogenic amine antibodies. Monocytes and granulocytes separated by size and granularity were also studied. RESULTS: Each biogenic amine could be detected in each subset of leukocytes, except epinephrine and serotonin in granulocytes. Activated T cells contained a higher amount of the amines, and CD19+B cells a higher amount of histamine, related to the whole lymphocyte population and to other subsets. Monocytes contained more histamine and epinephrine than lymphocytes and granulocytes contained twice as much histamine as monocytes and three times as much as lymphocytes. CONCLUSION: Human lymphocytes contain the three biogenic amine, similar to rat. However, while each amine was present in monocytes, in granulocytes serotonin and epinephrine were not demonstrated. The results call attention to the possible extrapolation of animal data to human lymphocytes and monocytes, but in the case of granulocytes, caution is needed. Taking into consideration earlier results, activated T cells appear to have an important role in the loss or production of hormones inside the immune system.