Murine CD2 gene expression during fetal thymus ontogeny

The expression of the murine CD2 gene and the interleukin 2 receptor IL2R has been investigated during fetal thymus ontogeny. CD2 mRNA was undetectable at embryonic day 14 but was readily detectable at day 15 of gestation. Surface IL2R expression was maximal at day 14 and was clearly detectable at day 13. These results indicate that IL2R expression precedes that of CD2 by at least 2 days.     

Soluble interleukin 2 receptor release, interleukin 2 production, and interleukin 2 receptor expression in activated T-lymphocytes in vitro.

Following activation in vitro, peripheral blood mononuclear cells (PBMC) express cell-associated interleukin-2 receptors (IL2R). The present study was undertaken to define the proportion of T lymphocyte subsets that express the IL2R (CD25 antigen) upon different mitogenic stimulation. Double immunofluorescence staining with different fluorochromes, fluorescein isothiocyanate and phycoethyrin, was applied for identification of IL2R positive cells and individual lymphocyte subset. The exact percentage of individual activated lymphocyte subset bearing IL2R was enumerated by photographic counting. There was paucity of IL2R in freshly isolated, unstimulated peripheral blood, PBMC cultured without mitogen, and cultured B lymphocytes. Following pokeweed mitogen stimulation in vitro, 19% of CD4 (T-helper/inducer) lymphocytes and 14% of CD8 (T-suppressor/cytotoxic) lymphocytes expressed IL2R. Similarly, 25% of CD4 lymphocytes and 19% of CD8 lymphocytes expressed IL2R following phytohemagglutinin stimulation in vitro. Contrary to the reported data of Tac-positive cells in human lymphoid tissues, our study revealed that, upon lectin mitogen stimulation, approximately 55% of IL2R positive PBMC were CD4 lymphocytes, and 45% of them were CD8 lymphocytes. These observations imply the plausible notion that interleukin-2 mediated immune activation of T lymphocytes in PBMC is different from that in local lymphoid organs. It was also demonstrated that the release of soluble IL2R (sIL2R) and IL2 production in supernatant from cultured PBMC varied with different lectin stimulation. A significant correlation was demonstrated between the cellular and soluble IL2R but the production of IL2 from activated mononuclear cells bore no good correlation with either the cellular IL2R expression or the release of sIL2R.     

Relationship between thymus ontogeny and DNA ligase expression in the chicken

DNA ligase expression was studied in the embryonic chicken thymus. As previously reported, during thymus ontogeny two separate and successive (8S and 6S) forms of enzyme are found. The switch from the heavy to the light form takes place at around 18 days of incubation in situ. The demonstration that two successive generations of thymic lymphoid precursor cells develop in the embryonic bird thymus and that the replacement of the first by the second thymocyte generation takes place at around 18 days suggested the possibility that each form of enzyme could be restricted to a given thymocyte generation. By either culturing or transplanting embryonic thymuses of different ages it appears that the switch from the heavy to the light form of DNA ligase is not related to a change over of the first by the second generation of embryonic thymocytes but rather to some maturation process of the thymic lymphocytes starting from 17 days of embryonic life. The influence of extrathymic factors on the turning on of the expression of the 6 S DNA ligase in the post-natal environment is also suggested.     

Partial characterization of the putative rat interleukin 2 receptor

T lymphoblasts of rat origin were (a) surface labeled with 125I and (b) internally labeled with 3H-marked sugars. Cell lysates were purified by immunoabsorption using the putative anti-rat interleukin 2 (IL2) receptor monoclonal antibody ART18 . The purified material was subjected to sodium dodecyl sulfate polyacrylamide gel electrophoretic analysis. Two specific membrane components were detected: a 50-kDa major and a 36-kDa minor component in reducing and a 45-kDA major and a 72-kDa minor component in nonreducing conditions, respectively. Both components were found to be susceptible to trypsinization and to neuraminidase treatment. 3H-labeled sugars were incorporated into the major component. The results indicate that the rat IL2 receptor is either a 50-kDa glycoprotein or a 36-kDa molecule, or that both components are part of the receptor molecule.     

T-lymphocyte activation in IgA nephropathy: Serum-soluble interleukin 2 receptor level,interleukin 2 production,and interleukin 2 receptor expression by cultured lymphocytes

The present study was undertaken to examine the T-lymphocyte activation in IgA nephropathy. Serum-soluble interleukin 2 receptor (sIL2R) levels were studied in 29 IgA nephritic patients, 17 patients with chronic glomerulonephritis (non-IgA nephropathy), and 30 healthy controls during an infection-free period. No difference in serum sIL2R level was demonstrated among these three groups of subjects. However, the serum sIL2R levels of IgA nephritic patient rose significantly during clinical exacerbation with synpharyngitic macroscopic hematuria and the serum sIL2R levels fell when hematuria subsided. Mitogen-stimulated cellular interleukin 2 receptor (IL2R) expression, sIL2R release, and interleukin 2 (IL2) production were also examined in peripheral blood mononuclear cells (PBMC) cultured for 24–48 hr in 21 patients with IgA nephropathy, 17 patients with chronic glomerulonephritides, and 17 healthy controls. The total cellular IL2R expression and sIL2R release did not differ among these three groups of subjects. However, the individual T-cell subsets bearing IL2R were distinctly different between IgA nephritic patients and the other two groups of controls. IgA nephritic patients had increased activated CD4+ lymphocytes and reduced activated CD8+ lymphocytes. Furthermore, IL2 production in response to phytohemagglutinin and pokeweed mitogen stimulation was increased in lymphocytes from patients with IgA nephropathy. The IL2 production did not correlate with the quantities of cellular and sIL2R yet the cellular IL2R expression paralleled the sIL2R released by cultured lymphocytes. Our present study suggests that the T lymphocytes from patients with IgA nephropathy have a defect in overproduction of IL2 and increased activated T helper-cell subset upon mitogenic stimulation. Serum measurement of sIL2R could potentially be useful in monitoring the disease activity.     

Suppression of interleukin 2 secretion and interleukin 2 receptor expression during tsetse-transmitted trypanosomiasis in cattle.

Infection with Trypanosoma congolense in cattle was found to be associated with a profound suppression of the host's immune system. Lymph node cells from infected cattle were unable to secrete interleukin 2 (IL 2) in vitro following mitogenic stimulation and the exogenous supply of IL 2 did not restore T cell proliferative responses. This was associated with an impaired expression of the alpha chain of the IL 2 receptor (IL 2R alpha). Co-culture experiments, where cells from an infected animal were mixed with cells from a major histocompatibility complex-matched normal animal, demonstrated the presence of suppressor cells capable of blocking both IL 2 secretion and IL 2R alpha expression. Removal of macrophages by fluorescence-activated cell sorting abrogated suppression in such co-cultures. Following depletion of macrophages, lymph node cells from an infected animal expressed IL 2R alpha at a normal level, but remained incapable of producing IL 2. Hence, the unresponsiveness was associated with macrophage-like suppressor cells which operated at the level of both IL 2 secretion and IL 2R alpha expression, and to an intrinsic unresponsiveness of the T cells which was restricted to IL 2 secretion. Inhibition of prostaglandin synthesis by addition of indomethacin failed to abrogate suppression of either IL 2 secretion or IL 2R alpha expression. This revealed a major difference between the regulation of suppression in murine model infections where the suppression of IL 2 secretion is due to prostaglandin secretion, and the situation in cattle where prostaglandins would not appear to be involved.     

Dual role of macrophages in the suppression of interleukin 2 production and interleukin 2 receptor expression in trypanosome-infected mice

Lymph node cells derived from T. brucei-infected mice fail to produce interleukin 2-(IL2) subsequent to a potent mitogenic trigger and actively suppress the capacity of normal cells to produce IL2 in co-culture experiments. The depletion of Thy-1+ cells does not decrease but rather increases the suppressive potential of the LNC derived from infected mice. A T cell-enriched nylon wool-nonadherent fraction, on the other hand, is not suppressive. The suppression of IL2 production is promptly restored by the addition of prostaglandin synthesis inhibitors suggesting a key role of the prostaglandin-producing macrophages. Our data indicate that such macrophages do not act indirectly through the induction of suppressor T cells, but rather directly interfere with the normal lymph node cells. In contrast to the essential role of prostaglandins in the impairment of IL2 production, these mediators are not involved in the suppression of IL2 receptor expression. Lymph node cells derived from Trypanosoma brucei-infected mice fail to produce interleukin 2 (IL2) subsequent to a potent mitogenic trigger and actively suppress the capacity of normal cells to produce IL2 in co-culture experiments. The depletion of Thy-1+ cells does not decrease but rather increases the suppressive potential of the LNC derived from infected mice. A T cell-enriched nylon wool-nonadherent fraction, on the other hand, is not suppressive. The suppression of IL2 production is promptly restored by the addition of prostaglandin synthesis inhibitors suggesting a key role of the prostaglandin-producing macrophages. Our data indicate that such macrophages do not act indirectly through the induction of suppressor T cells, but rather interfere directly with the normal lymph node cells.     

Experimental Trypanosoma brucei infections selectively suppress both interleukin 2 production and interleukin 2 receptor expression

Experimental infections with Trypanosoma brucei AnTat 1.1.E not only account for a suppression of interleukin 2 (IL 2) production, but also induce an impairment of IL 2 receptor expression. Indeed, lymph node cells derived from infected mice failed to express IL 2 receptors following mitogenic stimulation as compared to normal controls. This impairment was not attributed to a modulation of the number of T cells and was not caused by the presence of living parasites. Furthermore, the basal level of IL 2 receptor expression could not be re-established through the exogenous supply of recombinant IL 2. This impairment of receptor expression was found to be mediated by suppressive cells that affect the relative number of receptor-positive cells as well as the mean receptor density. On the other hand, the mitogen-induced secretion of other T cell-derived lymphokines was not inhibited during infection, indicating that the severe suppression of IL 2 regulation was not attributed to a total paralysis of the T cell responsiveness.     

The ontogeny of delta-9-tetrahydrocannabinol responsiveness in the rabbit

An autosomal recessive condition (thc/thc) in our closed colony of New Zealand White rabbits (Uaz:NZW-thc) results in nonfatal, behavioral convulsions following intravenous (i.v.) injections of delta-9-tetrahydrocannabinol (THC) and other psychoactive cannabinoids of marijuana. The ontogeny of the convulsive response was evaluated in potential THC-seizure-susceptible (SS) rabbits from postnatal Days (PN) 15-548. Ages of nonsusceptibility (PN 15-23), partial susceptibility (PN 24-38), and complete susceptibility (PN 39-548) were found. Also, open-field activity was determined in PN 14-25 THC-SS and THC-seizure-resistant (SR) rabbits. Administration of THC during the seizure-insensitive period resulted in genotype-dependent alternations in photocell activity and sprawling.     

Different mechanisms account for the suppression of interleukin 2 production and the suppression of interleukin 2 receptor expression in Trypanosoma brucei-infected mice

Lymph node cell populations derived from Trypanosoma brucei-infected mice failed to produce interleukin 2 (IL 2) in response to a potent mitogenic trigger and suppress the potential of normal lymph node cells to secrete IL 2 in co-culture assays. This suppression is promptly restored by the addition of indomethacin, which blocks prostaglandin synthesis, but is not markedly affected by the addition of catalase, which degrades H2O2. The suppression of the IL 2 receptor expression, on the other hand, is not restored by the addition of indomethacin, nor by the simultaneous supply of both indomethacin and catalase. This discrepancy is not caused by an extreme susceptibility of the receptor expression to low prostaglandin (PG) concentrations, but rather by the presence of suppressive cells that operate through a PG-independent mechanism. This suppressive mechanism accounts for the loss of the IL 2 receptors on both the Ly-2+ and the L3T4+ T cell compartment. The indomethacin-treated co-cultures, which manifest a normal IL 2 production but lack the IL 2 receptors, manifest an impaired DNA synthesis and contain a decreased number of T cell blasts.     

Phorbol ester-induced expression and function of the interleukin 2 receptor in human B lymphocytes

The expression of the interleukin 2 receptor (Tac) on normal B cells and Epstein-Barr virus-transformed lymphoblastoid B cell lines is induced by the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA). The receptor on B cells is indistinguishable from that on T cells by serological and biochemical analysis. It is functionally active so that TPA-induced B cells respond to interleukin 2 by increased DNA synthesis. These results suggest that the expression of Tac is not exclusively restricted to T cells and that interleukin 2 may play a role in B cell differentiation.     

Prolactin receptor in rat bile ducts in ontogeny

Expression of prolactin receptors (PR) in the nuclei and plasma membrane of the bile duct cells is demonstrated in 1-45-day-old male and female rats with the use of indirect immunoperoxidase technique. The intensity of PR staining in the bile duct cells is not sex-dependent; it increases from the 1st day till the 45th day and disappears by the 65th day of postnatal ontogeny. The PR-specific staining of hepatocytes also increases during the first 45 days of postnatal life and becomes sex-dependent by the 65th day. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 122, No. 12, pp. 669–672, December, 1996.     

Inhibition of interleukin 2 production and expression of the interleukin 2 receptor by plasma from acquired immune deficiency syndrome patients

Plasmas from acquired immune deficiency syndrome (AIDS) and AIDS-related complex (ARC) patients were screened for their ability to inhibit mitogen-induced proliferation of normal human lymphocytes. Plasmas from 67% of the individuals examined contained significant suppressive activity. Additional studies on the mechanism of action of the plasma inhibitor demonstrated that it functions as a nonlymphotoxic inhibitor of interleukin 2 production by stimulated human lymphocytes, and that this activity is accompanied by suppression of expression of the cell surface receptor for interleukin 2. A more detailed understanding of the action of this activity may aid in the design of therapy to minimize the contribution of this agent to the immune anergy observed in these patients.     

The ontogeny of interleukin production and responsivity in the frog, Xenopus

The production of and responsivity to leukocyte-derived lymphokine-rich culture supernatants (SNs) was examined during the ontogeny of the frog, Xenopus. Thymocytes and splenocytes from adult frogs are capable of responding to the T-cell mitogen, phytohemagglutinin-P (PHA). Larval thymocytes are unresponsive to this lectin, whereas larval splenocytes are not. PHA-unresponsive thymocytes can be costimulated with PHA plus either a T-cell growth factor (TCGF)-rich SN or an interleukin-1 (IL-1)-rich SN (from cultures of lipopolysaccharide (LPS)-treated macrophage-enriched peritoneal cells (PCs). Stimulation of larval thymocytes with PHA does not produce a TCGF-rich SN as assayed by proliferation of lymphoblasts. Larval as well as adult splenocytes treated with PHA, however, do produce TCGF. These data are consistent with the hypothesis that the factor limiting mitogen responsiveness of larval thymocytes is the ability of cell populations in the thymus to produce rather than respond to either IL-1 or IL-2.     

The ontogeny of acid alpha-naphthyl acetate esterase activity in the thymus

The acid alpha-naphthyl acetate esterase (ANAE) activity was examined in tissue sections of thymus from 24 fetuses, infants and children. ANAE activity was first detected in thymocytes at 11 wk of gestation, and the fraction of stained cells increased gradually until 18 wk of gestation. Thymocytes with circumscribed deposits of ANAE activity were observed as early as at 11 wk, whereas thymocytes with a diffuse, granular staining pattern were not observed before 16 wk of gestation.     

Multiple sclerosis: effect of myelin basic protein on interleukin 1, interleukin 2 production and interleukin 2 receptor expression in vitro.

The production of interleukin 1 (IL-1) and interleukin 2 (IL-2) by peripheral blood mononuclear cells (PBMC) stimulated with human myelin basic protein (MBP) was assessed in vitro in multiple sclerosis (MS) patients in relapse, patients with other neurological diseases (OND) and healthy subjects. Myelin basic protein significantly increased both IL-1 and IL-2 production by PBMC from MS patients during relapse when compared to OND patients or healthy controls. The most efficient concentration of MBP for the induction of IL-1 and IL-2 was 50 micrograms/ml. The optimal IL-1 production occurred after 48 h of PBMC culture and optimal IL-2 production after 72 h of PBMC culture. Anti-Tac monoclonal antibody (MoAb) was used to study IL-2 receptor expression on the same sample of PBM used for IL-2 study in MS patients in relapse. In addition IL-2 receptor expression was studied in PBMC from chronic progressive MS patients. In both MS groups IL-2 receptor expression on PBMC stimulated with MBP appeared higher than in control groups, but these differences were not statistically significant. IL-2 receptor expression on cerebrospinal fluid lymphocytes (CSF-L) either unstimulated or MBP-stimulated was, however, significantly higher in both MS groups when compared to OND patients. These results confirm the presence of activated lymphocytes in the CSF of MS patients during active stages of disease and suggest that this activation may be related to expansion of MBP specific cells.