Evaluation of early conception factor lateral flow test to determine nonpregnancy in dairy cattle

The early conception factor (ECF) lateral flow test was evaluated for its ability to accurately determine nonpregnant status in dairy cattle. Results of 2 field trials involving 191 cows and 832 tests indicated the probability that a cow can be correctly diagnosed as nonpregnant by using the ECF test is only about 50%. Agreement of test results between milk and serum obtained from the same cow was 57.5%. The ECF test was not consistent in identifying nonpregnancy when the same cows were tested repeatedly over a period of 4 weeks. We conclude that the ECF lateral flow test does not accurately identify nonpregnancy in dairy cattle.

Regeneration and tolerance factor prevents bystander T-cell death associated with human immunodeficiency virus infection

Human immunodeficiency virus (HIV) infection is characterized by a depletion of T cells. This depletion is caused both by the virus-induced death of infected T cells and by the death of uninfected cells (bystander depletion) by a mechanism which is largely uncharacterized. Regeneration and tolerance factor (RTF) is a subunit of the vacuolar ATPase and a protein that is involved with activation and apoptosis. Anti-RTF antibodies mediate apoptosis in T lymphocytes. When anti-RTF was added to lymphocytes from an HIV-positive individual, they underwent larger amounts of apoptosis than cells taken from healthy controls. When lymphocytes were examined by Western blotting, those from HIV-positive individuals exhibited increased levels of expression of the 50-kDa protein (P < 0.001). A 70-kDa protein was the predominant form of RTF in uninfected control lymphocytes, being expressed in 100% of individuals studied. The expression of the 50-kDa protein in HIV-positive individuals correlated with decreased absolute CD4 counts with a sensitivity of 92% and a positive predictive value of 86%. When uninfected lymphocytes were stimulated with anti-CD3 and anti-CD28, no RTF was detected during early stimulation but a 50-kDa protein was expressed during late stimulation. When the susceptibilities of the lymphocytes to anti-RTF-induced apoptosis were measured, they correlated with the size of the RTF protein expressed. The cells were not susceptible to apoptosis when the 70-kDa RTF was present but were susceptible when the 50-kDa RTF was present. We propose that the increase in the levels of the 50-kDa RTF on cells from HIV-positive individuals is important in preventing the cell from undergoing apoptosis.

Regeneration and tolerance factor modulates the effect of adenosine triphosphate-induced interleukin 1 beta secretion in human macrophages

These studies characterize a molecule known as regeneration and tolerance factor (RTF), which controls inflammation by regulating interleukin 1 beta (IL-1 beta) secretion. Recently, it has been demonstrated that the interaction of adenosine triphosphate (ATP) with the P2X7 purinoceptor induces the secretion of IL-1 beta and initiates the inflammatory response. In these experiments, that the addition of ATP to macrophages was found to induce P2X7 activation and secretion of IL-1 beta. This secretion is enhanced with anti-RTF antibody in combination with exogenous ATP (p< 0.005). RTF is also revealed to be able to influence surface ATPase activity and, increase PI incorporation, which is an indicator of P2X7 activation. We demonstrate that RTF has a role in controlling IL-1 beta secretion by regulating P2X7 activity.

Expression of a novel protein by regenerating hepatocytes and peripheral blood lymphocytes

Regeneration and tolerance factor (RTF) is a protein with immunosuppressive activity and is normally present in the thymus and placenta. RTF was measured in the livers of patients with regenerating nodules due to alcoholic cirrhosis and hepatitis C. RTF was expressed in the regenerating nodules of 26 patients with alcoholic cirrhosis. All patients with chronic hepatitis C without cirrhosis failed to express RTF. Flow cytometry revealed upregulation of RTF on the lymphocytes from alcoholic cirrhosis and downregulation in hepatitis C disease.

Regeneration and tolerance factor: a correlate of human immunodeficiency virus-associated T-cell activation

Human immunodeficiency virus (HIV) infection causes extensive phenotypic alterations in lymphocytes. Cellular markers that are normally absent or expressed at low levels on quiescent cells are upregulated throughout the disease course. The transmembrane form of regeneration and tolerance factor (RTF) is expressed at negligible levels on resting T cells but is quickly upregulated following in vitro stimulation and activation. Recently, we reported that expression of RTF was significantly higher in cells from HIV-seropositive (HIV(+)) individuals than in cells from HIV-seronegative (HIV(-)) individuals. Because T cells from HIV(+) individuals express markers reflecting chronic activation, we hypothesized that these in vivo-activated cells would coexpress RTF. Flow cytometry was used to assess RTF expression on activated (CD38(+) and HLA-DR(+)) CD4(+) and CD8(+) T cells. HIV(+) individuals had higher percentages of RTF(+) CD38(+) (P < 0.0001) or RTF(+) HLA-DR(+) (P = 0.0001) CD4(+) T cells than HIV(-) individuals. In HIV(+) individuals, increased percentages of CD4(+) T cells that were RTF(+), RTF(+) CD38(+), and RTF(+) HLA-DR(+) correlated inversely with the absolute number and percentage of CD4(+) T cells and correlated positively with plasma beta(2)-microglobulin concentrations. HIV(+) individuals had higher percentages of CD8(+) T cells that were RTF(+) CD38(+) (P = 0.0001) or RTF(+) HLA-DR(+) (P = 0.0010). In HIV(+) individuals, increased percentages of CD8(+) T cells that were RTF(+) HLA-DR(+) correlated inversely with the percentage of CD4(+) T cells, and high percentages of CD8(+) T cells that were RTF(+) CD38(+) correlated positively with plasma beta(2)-microglobulin levels. These findings strongly suggest that increased RTF expression is a correlate of HIV-associated immune system activation.

Estradiol-17 beta and progesterone increase ovine uterine suppressor cell activity

We evaluated the regulation of ovine uterine (UT) suppressor cell activity by progesterone (P4), estradiol-17 beta (E2), and P4 + E2 in ovariectomized (OVX) ewes. Following 14 d of steroid injections, endometrial cells (designated as UT cells) were recovered postmortem, and unfractionated and fractionated cells were assessed for suppression of autologous phytohemagglutinin (PHA)-treated peripheral blood lymphocytes (PBL). Supernatants from cultured UT cells were also assessed for suppressor activity. In other experiments, UT cells recovered from nontreated OVX ewes were cocultured with PHA-treated PBL and varying concentrations (1 x 10(-11) to 1 x 10(-5) M) of each steroid preparation. Supernatants from separate cultures that contained UT cells and steroids were evaluated for suppressor activity. Uterine cells from control and steroid-treated ewes suppressed proliferative responses of PHA-treated PBL; however, suppressor activity of UT cells was greater (P < .05) for E2-treated than for control and P4-treated ewes. Uterine suppressor cells from steroid-treated ewes sedimented in Percoll within a density range of 1.002 to 1.056 g/mL. Uterine cells from all ewes released suppressor factor(s) into the culture medium; however, the activity of the supernatant from the cultured cells was not increased for the steroid-treated ewes. For cocultures that contained steroids and cultures that contained supernatant, suppressor activity of the UT cells was increased by specific concentrations of each steroid preparation. These findings demonstrate that reproductive steroids augment ovine UT suppressor cell activity.

V alpha 14+ NK T cells: a novel lymphoid cell lineage with regulatory function

A novel lymphoid lineage, NK T cells, was recently found. The NK T cells are the major population in the periphery comprising 5% of splenic T cells and 40% of bone marrow T cells. They express a unique TCR composed of invariant V alpha 14J alpha 281 and V beta 8.2 together with NK receptor (NKRPI). Surprisingly, the invariant V alpha 14+ TCR is exclusively expressed on NK T cells but not on conventional T cells. As the selective decrease in V alpha 14+ NK T cell population in the periphery is tightly correlated with autoimmune disease development, V alpha 14+ NK T cells control development of autoimmune diseases. We also found that V alpha 14 TCR gene rearrangement and transcripts were detected at an early embryogenesis (d9.5) before the thymus formation. Therefore NK T cells are in the distinct category from conventional T cells. The target of NK T cells is found to be CD1 (class 1b, monomorphic class I MHC-like molecule) present on bone marrow-derived cells and is killed by Fas-FasL interaction or perforin-mediated mechanisms. These results indicate that NK T cells consist of an immunoregulatory system different from defense system in terms of homogeneous repertoire, extrathymic development in early stage of gestation, and their regulatory functional role.

Immunosuppression after endotoxin shock: the result of multiple anti-inflammatory factors

OBJECTIVES

Endotoxin induced suppression of cellular immune function is thought to contribute to septic complications in trauma patients. A rabbit model of endotoxemia was used to determine the relative roles of the anti-inflammatory factors interleukin-4 (IL-4), interleukin-10 (IL-10), transforming growth factor beta1 (TGFbeta1), and prostaglandin E2 (PGE2) in addition to other factors, in inducing immunosuppression.

DESIGN

T-cell suppressive factors (TSF) in serum ultrafiltrates were separated and tested for the presence of the known suppressive factors PGE2, IL-4, IL-10, and TGFbeta1.

MATERIAL AND METHODS

New Zealand rabbits were injected with 50 microg/kg of purified Escherichia coli lipopolysaccharide. Animals were exsanguinated after 48 hours and serum was separated by ultrafiltration (cutoff 50 kd), TSK HW-40 size exclusion chromatography, and Q-Sepharose anion exchange chromatography. TSF activities of chromatographic fractions and serum samples were measured with a mitogen induced in vitro T-cell proliferation assay. Levels of PGE2, IL-4, IL-10, and TGFbeta1 were measured with enzyme immunoassays.

MEASUREMENTS AND MAIN RESULTS

Serum TSF activity, and levels of PGE2, IL-4, IL-10, and TGFbeta1 were increased after endotoxemia. Size exclusion chromatography revealed three major fractions (TSF1-3) with up to 600 times more TSF activity compared with controls. IL-4 and IL-10 were found in TSF1 and TSF3. Further separation of TSF1 by anion exchange chromatography revealed a total of eight different T-cell suppressive factors. TGFbeta1 probably remained in the retentate after ultrafiltration, while PGE2 eluted at a higher retention time. The known anti-inflammatory factors TGFbeta1, IL-10, IL-4, and PGE2 only accounted for 13% of the total serum TSF activity of 614 U/mL.

CONCLUSIONS

Lipopolysaccharide shock results in the release of multiple T-cell suppressive factors in addition to known immunosuppressive factors, all of which contribute to the anti-inflammatory response.

Saliva of the Lyme disease vector, Ixodes dammini, blocks cell activation by a nonprostaglandin E2-dependent mechanism

Tick-borne pathogens would appear to be vulnerable to vertebrate host immune responses during the protracted duration of feeding required by their vectors. However, tick salivary components deposited during feeding may inhibit hemostasis and induce immunosuppression. The mode of action and the nature of immunosuppressive salivary components remains poorly described. We determined that saliva from the main vector of the agent of Lyme disease, Ixodes dammini, profoundly inhibited splenic T cell proliferation in response to stimulation with concanavalin A or phytohemagglutin, in a dose-dependent manner. In addition, interleukin 2 secretion by the T cells was markedly diminished by saliva. Tick saliva also profoundly suppressed nitric oxide production by macrophages stimulated with lipopolysaccharide. Finally, we analyzed the molecular basis for the immunosuppressive effects of saliva and discovered that the molecule in saliva responsible for our observations was not PGE2, as hypothesized by others, but rather, was a protein of 5,000 mol wt or higher.

H5D12 monoclonal antibody identifies a 24-kD immunosuppressor factor produced by human chorio carcinoma cells

PROBLEM

The purpose of this study was to identify and characterize embryo-associated immunosuppressor factor (EASF) secreted by chorio carcinoma cells with the help of EASF-specific monoclonal antibody H5D12 (raised against EASF purified from embryo growth media of in vitro fertilized human ova).

METHOD

Paraffin-embedded slides of human chorio carcinoma as well as control cell lines were prepared, and immunohistochemistry was done by the avidin-biotin-peroxidase technique. EASF was affinity purified using H5D12-Sepharose 4B from culture media of cell lines and analyzed for immunosuppressive activity (by Concanavalin-A-induced lymphocyte proliferation assay) and molecular weight identity (by metabolic-labelling studies with 35S-methionine followed by immunoprecipitation and SDS-PAGE).

RESULTS

H5D12 showed intense immunostaining of BeWo chorio carcinoma cells. Biosynthetic labeling studies identifies this factor as a 24-kD molecule, and EASF bioassay indicates that this factor possesses immunosuppressive activity. No such immunosuppressive activity or similar molecules were identified when control cell lines were analyzed.

CONCLUSIONS

Monoclonal antibody H5D12 recognizes a 24-kD factor with immunosuppressive activity that is secreted by chorio carcinoma cells, which suggests that this is a unique factor and may be one of the key regulators of reproductive functions.

Mast cells display natural suppressor activity partially by releasing transforming growth factor-beta

We have previously reported a method for inducing natural suppressor (NS) cells by long-term culture of normal adult mouse spleen cells. The NS cells were further identified as mucosal or immature mast cells by morphology, cytochemistry, histochemistry and function. A cloned immature mast cell line was also confirmed to have NS activity. As NS cells, the cell line suppressed non-specifically the plaque-forming cell (PFC) response. The NS cell-free supernatant was partially enriched by chromatography and some fractions suppressed the PFC response and thymocyte proliferation. Heat treatment of the fractions failed to deplete the suppressive activity. The fractions were confirmed, by immunoblotting analysis, to contain transforming growth factor (TGF)-beta. Recombinant human TGF-beta was also able to suppress the PFC response and thymocyte proliferation. Neutralizing anti-TGF-beta reversed the suppression by both human TGF-beta and the fraction. From the above results, it is clear that mast cells displayed NS activity, at least partially, through the release of TGF-beta.

IgG4 binding factor in human seminal plasma identified as heavy chain of immunoglobulin

Human seminal plasma contains a factor that binds human immunoglobulin G (IgG). The factor has an estimated M(r) of 50 kD and interacts specifically with human IgG4. It does not bind other subclasses of human IgG or IgGs of other mammalian species tested. The factor was purified by affinity chromatography on protein G column. The 50-kD component was eluted in the adsorbed fraction and immunostained with monoclonal antibodies against heavy chain (gamma) of IgG. Purified subclasses of human serum IgG were separated into heavy and light chains by sodium dodecyl sulfate polyacrylamide gel electrophoresis under reduced condition. The heavy chains of all subclasses of IgG bound IgG4. The present findings suggest that the 50-kD IgG4 binding factor of human seminal plasma is the heavy chain of IgG.

Expression of a membrane form of the pregnancy-associated protein TJ6 on lymphocytes

TJ6 is a novel protein which has immunosuppressive activity and may have a functional role in fetal allograft survival during pregnancy. Initial studies indicated that when mice were treated with an anti-TJ6 binding mAb early in pregnancy, the pregnancies were completely ablated and that TJ6 expression is enhanced dramatically during pregnancy. In addition we have cloned the cDNA for TJ6 which encodes a possible transmembrane domain that may include six to seven transmembrane regions. Therefore, we examined TJ6 expression on PBL of pregnant and non-pregnant women and found that TJ6 is expressed primarily on CD19+ B cells from pregnant but not nonpregnant women. TJ6 was not expressed on CD3+ lymphocytes from either group but was expressed on CD56+ cells from a small population of pregnant women which preliminary data indicate may correlate with the occurrence of spontaneous abortion in these women. Here we also show that TJ6 transcripts are highly expressed in the developing fetoplacental unit as well as in the developing thymus. We also begin to characterize the expression of TJ6 isoforms in an acute lymphocytic leukemia cell line (SB), murine thymus, and the developing murine fetoplacental unit, as well as the expression of a membrane form of TJ6 present on human lymphocytes during pregnancy. All of these cells and tissues expressed TJ6 proteins which were smaller than predicted based on either the cDNA sequence or the in vitro translation even though they expressed mRNA similar in size. The TJ6 isoforms varied in size from the 45-kDa isoform in SB cells to the 52-kDa isoform of the fetoplacental unit to a 70-kDa isoform in murine thymus. Flow cytometric analysis also demonstrated that similar to the CD19+ B cells from pregnant women, TJ6 is expressed on the surface of SB cells.

Production and characterization of monoclonal antibodies to embryo-associated immunosuppressor factor (EASF) produced by human pre-implantation embryo

Balb/c mice were immunized with pre-implantation embryo-associated immunosuppressor factor (EASF) (purified from embryo growth media of in vitro fertilized human ova). Hybridoma clones were produced by fusing their spleen cells with NS1 and P3X653 myeloma cell lines. The presence of specific anti-EASF monoclonal antibodies (mAb) in the hybridoma culture supernatants were tested by enzyme-linked immunosorbent assay. A total of 15 hybridoma clones were selected, and their products were purified and characterized. Each mAb bound specifically to its antigen in a dose-dependent manner. The affinity-purified EASF from embryo growth media demonstrated immunosuppressive activity on Concanavalin A-induced lymphocytes and the presence of 14 kDa, 24 kDa and 37 kDa factors. No such activity or similar molecules were identified when control growth media were analyzed. This clearly demonstrates that these mAb are indeed EASF-specific and are able to recognize biologically active immunosuppressive components in embryo growth media. These mAbs are presently being tested for the development of EASF-specific assay system.

Suppressor function of liver mononuclear cells isolated during murine chronic graft-vs-host disease. II. Role of prostaglandins and interferon-gamma

Mononuclear inflammatory cells (MC) isolated from the livers and spleens of mice with chronic graft-vs-host disease (CGVHD) to minor histocompatibility antigens (B10.D2----BALB/c) show defective proliferation when stimulated with Con A and LPS. In turn, both CGVHD liver and spleen cells suppress the proliferation of mitogen-stimulated normal spleen cells in a genetically unrestricted manner. The suppressor activity of CGVHD spleen cells is mediated by plastic nonadherent null (natural suppressor) cells and involves a soluble suppressor factor(s). In contrast, the suppressor activity of CGVHD liver cells is mediated by macrophages (M phi). In the current studies we show that the suppressor activity of CGVHD liver cells is also mediated by soluble factors and compare the roles of prostaglandins and interferon (IFN)-gamma in mediating defective proliferation and suppressor activities of CGVHD liver and spleen MC. Monoclonal antibody to IFN-gamma partially reversed the defective mitogen-stimulated proliferation of CGVHD spleen MC but had no effect on proliferative response of CGVHD liver MC. Indomethacin did not alter the low proliferative response of either CGVHD liver or spleen MC. Anti-IFN-gamma inhibited the ability of CGVHD spleen cells to suppress proliferation of Con A and LPS-stimulated B10.D2 spleen cells. In contrast, anti-IFN-gamma resulted in a small decrease in the ability of liver MC to suppress Con A (but not LPS)-stimulated cell proliferation. Indomethacin decreased the ability of both CGVHD liver and spleen cells to suppress Con A-stimulated proliferation but had inconsistent effects on LPS-stimulated proliferation. These results show that IFN-gamma and prostaglandins partially mediate the suppressor activity of CGVHD spleen MC. The suppressor activity of CGVHD liver MC also involves prostaglandins but is relatively independent of IFN-gamma.

Induction of CD8+ suppressor T cells by treatment with DMBA and TPA in vitro

Antigen-nonspecific CD8+ T suppressor cells, which suppressed delayed-type hypersensitivity (DTH) against sheep red blood cells in BALB/c mice, were induced by incubating spleen cells from mice treated with 7,12-dimethylbenz[a]anthracene (DMBA), a tumor initiator, with 12-O-tetradecanoylphorbol 13-acetate (TPA), a tumor promoter. The optimal condition was incubation in 3.2 x 10(-8) mol/5 ml of TPA for 4 days. It was shown that induction of the suppressor cells required macrophages from mice treated with DMBA. These data were consistent with the results of previous work, in which CD8+ suppressor cells were induced by painting BALB/c mice with TPA following DMBA treatment. DTH was suppressed in the culture supernatants of spleen cells from mice treated with DMBA and TPA; the suppression was genetically unrestricted. The suppressor factor was resistant to trypsin and sensitive to heating at 56 degrees C for 30 min and had affinity for the macrophages.

Regulation of lymphocyte blastogenesis and antibody production by soluble factor released by a human B-lymphoblastoid cell line

Yam 1B, a human B lymphoblastoid cell line, spontaneously produced an immunoregulatory factor, which suppresses blastogenesis and antibody formation by human lymphocytes. The Yam 1B cells, which were derived from the peripheral blood of an adult T-cell leukemia patient, have been established and maintained in our laboratory since 1985. This cell line expressed mature B-cell surface antigens including surface immunoglobulin M (IgM), CD23, and HLA-DR; had cytoplasmic IgM; and secreted small amounts of IgM in the culture supernatants. Yam 1B was positive for Epstein-Barr virus-associated antigen (EBNA) but negative for adult T-cell-associated antigen (ATLA). The serum-free Yam 1B culture supernatants (SN) inhibited the expression of transferrin R, but neither the expression of interleukin 2 (IL-2) R(CD25) nor the production of IL-2 in the lymphocytes stimulated with phytohemagglutin. Yam 1B SN also inhibited DNA synthesis by human T and B lymphocytes and immunoglobulin generation by normal B cells as well as by Epstein-Barr virus-transformed human B lymphoblastoid cell lines. The inhibitory activity of Yam 1B SN was inactivated at 56 degrees C and at pH 10 but was relatively stable at pH 2. It was abrogated by digestion with pronase and was partially stable by digestion with trypsin. Fractions collected from a Sephacryl S-300 gel filtration column (Pharmacia Fine Chemicals, Uppsala, Sweden) were found to have a peak of inhibitory activity of cell proliferation associated with molecules of apparent MWr of 43,000 to 67,000. The inhibitory activity of Yam 1B SN was not blocked by the anti-transforming growth factor beta antibody.(ABSTRACT TRUNCATED AT 250 WORDS)

Serologic, biologic, and western blot analysis of a T suppressor factor with specificity for the hapten 4-hydroxy-3-nitrophenyl acetyl derived from serum-free medium

A T cell hybridoma producing a T suppressor factor (TsF) with specificity for the hapten nitrophenyl was converted to long term growth in serum-free medium and its product tested by serology, bioactivity, and Western blot analysis. Results indicated that Ag-specific suppressive activity was present in serum-free medium and this TsF could exhibit the characteristics ascribed to it by various groups: it could bind nominal Ag with specificity, it was bound by anti-TsF mAb, and it could mediate Ag-specific suppression both in vivo and in vitro. Western blot and SDS-PAGE analysis of this purified TsF revealed a 43-kDa single chain protein.

Detection of immunoregulatory lipid-like factors in human amniotic fluid

The immunosuppressive activity of amniotic fluid (AF) is extensively documented in the mouse. Although this property is due in part to the presence of alpha-fetoprotein (alpha-FP), other immunosuppressive factors are suspected. In this article, we demonstrate that human amniotic fluid lipid extract (AFLE) is inhibitory of, although not cytotoxic to, PHA-activated human lymphocytes, of mouse bone marrow cells, and of different established cell lines of human and mouse source. This effect is shown to be reversible. Under preparative thin layer chromatography (TLC) using chloroform:methanol:water (60:38:8) as solvents, the activity of AFLE migrates to two peaks of inhibition with Rf values of 0.46-0.62 and 0.84-1, respectively. These lipid-like factors may play a role as a nonspecific immunoregulatory mechanism which prevents maternally mediated immune rejection of the conceptus.

[Cellular mechanisms of suppression of T-lymphocyte proliferation by lung cells in experimental tuberculosis]

The ability of interstitial lung cells from mice, infected with Mycobacterium tuberculosis H37Rv, to suppress proliferative responses of immune lymphocytes to mycobacterial (PPD) and unrelated (Staphylococcus aureus cytoplasm) antigens was studied. Two types of suppression were observed: the specific one, which was characteristic of the PPD-response only; and non-specific. The latter was mediated mainly by prostaglandins, since it could be abolished by indomethacin. Both types of suppression depended on the presence of plastic and nylon wool adherent phagocytes from infected lung. Though the depletion of T or B lymphocytes from the lung cell population have not abrogated the suppressive effect, some intercellular interactions were required for antigen-specific suppression, since the presence of nylon wool adherent cells in the population of responder lymph node cells was necessary for its development.

Aqueous humor contains transforming growth factor-beta and a small (less than 3500 daltons) inhibitor of thymocyte proliferation

The anterior chamber of the eye is an immunologically privileged site in which allografts survive longer than at other body sites. In this regard, it is relevant that aqueous humor (AH) inhibits lymphocyte proliferation. In order to analyze AH for specific substances that inhibit thymocyte proliferation, samples of human AH, murine AH, and rhesus monkey AH were added to cultures of thymocytes stimulated by IL-1 or IL-2 in the presence of PHA. All samples of AH tested had potent inhibitory activity on thymocyte proliferation in this system. Inhibitory activity was lost by heating AH to 80 degrees C for 1 h. Dialysis of murine AH indicated that species smaller than 3500 Da were capable of mediating this activity; we have termed the factor(s) responsible for this "small inhibitory factor(s) of AH." Retentate, containing species larger than 3500 Da, retained inhibitory activity, but less than nondialyzed AH. Assays for PGE2 demonstrated that murine and human AH contained small quantities of PGE2. These quantities were insufficient to inhibit thymocyte proliferation in our assay system. Furthermore, AH from mice treatend with indomethacin had full inhibitory activity. Assays for transforming growth factor beta (TGF-beta) after acid activation demonstrated significant quantities of latent TGF-beta within human and murine AH which could be largely neutralized by antisera to TGF-beta. Active TGF-beta "activity" was also present without acid activation in samples of AH at a level approximately 20% that of latent TGF-beta. However, most of this "activity" could not be neutralized by antisera to TGF-beta. AH contains factors capable of limiting thymocyte proliferation.

Murine pregnancy decidua produces a unique immunosuppressive molecule related to transforming growth factor beta-2

Non-T small lymphocytic suppressor cells in murine allopregnancy release a potent immunosuppressive factor in vitro that is neutralized by rabbit anti-transforming growth factor (TGF)-beta. Previous studies have suggested that the decidual suppressor factor (DSF) is smaller than TGF-beta 1, and in this paper, we show that DSF on HPLC-sieving columns also elutes later than TGF-beta 2. Nevertheless, DSF has the ability to promote anchorage-independent growth of NRK fibroblasts similar to TGF-beta s. Using turkey antibodies specific for TGF-beta 1 or beta 2, we show that DSF is related to TGF-beta 2 rather than TGF-beta 1, and this relationship was confirmed by using a panel of murine mAb to TGF-subtypes. PAGE and Western blotting showed that the TGF-beta 2-reactive molecules in HPLC-purified DSF was slightly smaller than TGF-beta 2 and approximately 20 to 23 kDa. The DSF molecule is therefore closely related to TGF-beta 2 but as released from decidua, differs in size. The TGF-beta 2-related decidual suppressor factor was also obtained from the decidua of synpregnant C.B.-17 severe combined immune deficiency (SCID) and pregnant SCID-BG (C57BL/6 background) mice, confirming the lack of T or B cell dependence of DSF production and the generality of production of a TGF-beta-related suppressor factor by decidua associated with successful pregnancy in mice.

A method to generate antigen-specific suppressor T cells in vitro from peripheral blood T cells of honey bee venom-sensitive, allergic patients

Peripheral blood mononuclear cells of patients allergic to honey bee venom were stimulated with denatured bee venom phospholipase A2, and the antigen-activated T cells were propagated for 4 days by human IL-2 in the presence or absence of recombinant human lipocortin I. Upon antigenic stimulation with the denatured phospholipase A2 and autologous monocytes or by cross-linking of CD3 by anti-CD3 antibody, the activated T cells, which had propagated by IL-2 alone, formed N-glycosylated IgE-binding factors and glycosylation enhancing factor (GEF), while those propagated in the presence of lipocortin formed unglycosylated IgE-binding factors and glycosylation inhibiting factor (GIF). The GEF and GIF formed by the antigen- or anti-CD3-stimulated T cells had affinity for bee venom phospholipase A2 and could be purified by using anti-lipomodulin Sepharose. In the mouse lymphocyte system, the major cell source of GIF is antigen-specific suppressor T cells, and the antigen-binding GIF from the cells suppressed the in vivo antibody response in an antigen (carrier)-specific manner. In view of the findings in the mouse system, the present results may provide an immunological maneuver to generate allergen-specific suppressor T cells, and to obtain allergen-specific suppressor factor from T cell populations in the peripheral blood of allergic patients.

Biochemical identification of glycosylation inhibiting factor

Rat monoclonal antibody against mouse glycosylation inhibiting factors was obtained, and radiolabeled glycosylation inhibiting factors from the mouse T-cell hybridoma, 231F1 cells, were purified by using the monoclonal antibody and antilipomodulin antibody. Analysis of the affinity-purified lymphokine by PAGE demonstrated two proteins of 14.4 kDa and 41 kDa. Both proteins migrated similarly under the reduced and unreduced conditions, indicating that each of the two species consist of a single polypeptide chain. Biologic activity of the lymphokine was recovered by extraction of the proteins from gel slices followed by renaturation. Evidence was obtained that suggested the 14.4-kDa peptide was a degradation product of the 41-kDa molecules. The 14.4-kDa peptide was also recovered by extraction of the surface-labeled 231F1 cells with Ca2+ chelator, indicating that the glycosylation inhibiting factor is associated with the cell surface.

The analysis of lymphocyte surface receptors recognized by wheat germ agglutinin for negative regulation of immune responses in cancer patients

The population of peripheral blood lymphocytes expressing surface receptors for a lectin, wheat germ agglutinin (WGA), which has been shown to recognize the same receptors as the soluble immune suppressor factor (SISF) elaborated from suppressor cells on the lymphocyte surface, was analyzed by using fluorescein isothiocyanate-conjugated WGA on flow cytometry in cancer patients. It was found that the populations of WGA+ lymphocytes in cancer patients were significantly higher than those in either normal volunteers or patients with benign disease and increased with progress of the tumor. The populations decreased after treatment in patients who underwent curative resection of the tumor and in responders of immunochemotherapy but not in those who received non-curative surgery or in non-responders. It was suggested that the increase of receptors for SISF on the lymphocyte surface might play an important role in the negative regulation of immune responses in cancer patients and that WGA might be a useful parameter for immunosuppression.

[Effects of humoral factors of the mastocytoma P815 cells on the formation of allospecific killers in mixed culture of lymphocytes and their cytotoxic activity]

The influence of the P-815 mastocytoma cells and their humoral factors, contained in culture supernatant and ascitic fluids on the generation of allospecific cytotoxic T-cells (alloCTL) in mixed culture of lymphocytes was studied. Both tumor cells and humoral factors were shown to inhibit generation of allospecific killers. Normal spleen cells and peptonic ascites of DBA/2 mice did not indicate immunosuppressive activity. Immunosuppressive factors did not affect CTL effector function (lysis of target cells). Both tumor cells and immunosuppressive factors did not exert toxic effect on mouse splenocyte. The suppressive effect of tumor cells and humoral factors was not associated with their cytotoxic action on lymphocytes.

Modulation of the immunosuppressive activities by blastocoelic fluid during rabbit pregnancy

Temporal variation in immunosuppressive activity was determined in biological samples such as embryo-foetal fluids (blastocoelic- or amino-allantoic fluid) and blood collected from pregnant and pseudopregnant rabbits. Each of the fluids to be analyzed was pre-incubated with mitogen stimulated human lymphocytes for 48 h and then inhibition of [3H]thymidine incorporation or IL-2 receptor expression was estimated. Both means of assessing immunosuppression indicated variations in the suppressive activity throughout pregnancy. This was observed in embryo-foetal fluids but not in autologous peripheral blood nor in homologous pseudopregnant blood. At days 9-13 of pregnancy, the immunosuppressive effects of blastocoelic fluids were higher than that of the autologous sera, reached a peak at days 12 and 13 and declined thereafter, to reach the lowest levels. In order to further characterize the biological activity of day-12 blastocoelic fluid and autologous serum, they were submitted to ultracentrifugation. No suppressive activity could be demonstrated in the lipoprotein fractions. But all the activity was found in the protein fraction. Precipitation with cold ethanol confirmed that the biologically active compound was a protein. Furthermore, results obtained after ultrafiltration suggest biologically active compounds of high mol. wt (greater than 300 kDa). From the above findings, we can suggest that in the rabbit, there is no pregnancy specific systemic immunosuppression. We can also infer that (1) the immuno-tolerance of the mother towards the embryo is more due to a localized effect; (2) this effect decreases with the progression of gestation and (3) a high mol. wt factor is responsible for the immunosuppression.

Characterization of a suppressor factor that regulates phagocytosis by macrophages in murine cryptococcosis

A T-suppressor factor which inhibits the phagocytic activity of a macrophage subset has been further characterized. This suppressor factor was first described for a murine model of cryptococcosis but was later found to be common to models of immunologic unresponsiveness. The suppressor factor was produced when suppressor cells were cultured in the presence of specific cryptococcal antigen. It could not be extracted from spleen cells and was not induced by antigen in cultures of lymph node cells. The suppressor factor was filtered through Amicon filters of 100-kilodalton (kDa) exclusion limit but was retained by filters excluding molecules of less than 50 kDa. By Sephadex G-100 chromatography, the factor eluted just ahead of bovine serum albumin (68 kDa). The activity of the suppressor factor could not be inhibited by anticryptococcal antibody, but it was inhibited by anti-I-J alloantiserum of the same genotype as the lymphocyte which produced the factor. Absorption with an encapsulated strain of Cryptococcus neoformans removed the suppressor factor from culture supernatants, while absorption with a nonencapsulated mutant or an unrelated yeast cell had not effect. On the basis of these observations, it was apparent that the suppressor factor was idiotypic in nature and that I-J and/or the I-J-interactive molecule played a role in the function of the suppressor factor. The requirement for antigenic stimulation for the production of suppressor factor in vitro distinguished it from the T-suppressor factor 3 described by others which regulates delayed-type hypersensitivity in cryptococcosis.

A circulating suppressive factor of platelet cytotoxic functions after rush immunotherapy in Hymenoptera venom hypersensitivity

A receptor for the Fc fragment of IgE has been described on human blood platelets. This receptor mediated the IgE-dependent stimulation of platelets by the specific allergen in Hymenoptera venom (HV) hypersensitivity. This platelet reactivity was abolished after rush desensitization. To understand the mechanism of such a down-regulation, we studied the effects of sera recovered from patients treated by HV rush desensitization on platelets of untreated HV sensitive patients. The present data describe the presence of a circulating factor able to suppress, in a dose-dependent manner, platelet stimulation by the specific allergen. This circulating factor was not allergen specific, not depleted by IgE or IgG antibody immunoadsorption, and was found at higher concentrations in the sera of patients receiving monthly high dosages of HV (200 micrograms maintenance dose). The physicochemical characterization showed that this circulating factor had a m.w. of 20,000 to 25,000, an isoelectric point of 4.2, was heat and acid stable, and sensitive to trypsin, but not to neuraminidase. These characteristics were similar to a newly described lymphokine, platelet activity suppressive lymphokine, suggesting the intervention of such a lymphokine in HV rush desensitization.

Characterization and analysis of soluble suppressor factor from early human decidual cells

To assess the role of decidual cells (DC) in the maintenance of pregnancy, immunosuppressive activity of culture supernatants from human DC were investigated. Dispersed DC suspensions from decidual tissue of early pregnancies were prepared by an enzyme digestion method using collagenase and DNase, and were enriched over 90 per cent without contamination of macrophages and lymphocytes in the fraction, with specific gravity between 1.033 and 1.044 (fraction 2 [Fr2] ) by a Percoll discontinuous density gradient method. The culture supernatants of Fr2 cells suppressed the responses of normal peripheral blood lymphocytes to PHA, MLR, and killer T cell generation at the 50 per cent concentration. To determine the mechanism of the immunosuppressive activity of the culture supernatants, the effect of the supernatants on interleukin-2 and gamma-interferon production, as well as IL-2 receptor expression, on PBL was investigated. The supernatants from 3 x 10(6)/ml of DC cells inhibited not only IL-2 and gamma-INF production, but also IL-2 receptor expression, compared with normal controls. The supernatants also suppressed immunoglobulin (IgG and IgM) production by pokeweed mitogen-stimulated B cells. To purify the suppressor factor from culture supernatants of DC, serum free culture supernatants of 3 x 10(6)/ml of DC, which showed 32 per cent of inhibitory activity on MLR, were applied to gel filtration. Fractions between mw 67,000 and 43,000 suppressed the MLR. These results suggest that DC from decidua of early pregnancy excrete an immunosuppressive factor with a molecular weight between 43,000 and 67,000 daltons.

Trophoblast-derived immunoregulatory factor: demonstration of the biological function and the physicochemical characteristics of the factor derived from choriocarcinoma cell lines

An immunosuppressive factor released by choriocarcinoma cell lines was analyzed in the present study. It inhibited the proliferative responses of human T cells stimulated by lectins or alloantigens. It also blocked the generation of alloreactive cytotoxic T cells. The suppressive activity of the factor was detected in the responses of the T cells costimulated with 1 nM 12-O-tetradecanoyl phorbol 13-acetate and 1 microM A23187, suggesting the possibility that the factor acted on the intracellular signal transduction in T cells rather than interfering with early events such as T cell receptor signal transduction through cell membranes. Moreover, the factor acted directly on T cell proliferation pathways without activation of suppressor cells but did not act on T cell activation pathways. Taken together, all these findings expanded our previous reports on a factor released by normal trophoblasts, indicating the possible identity of the two factors. The physicochemical properties of the choriocarcinoma-derived factor were examined, and the biological significance of the factor during pregnancy was discussed in this paper.

Abnormalities of serum proteins following thermal injury

Suppressive factors were found to be present in serum and considered to be one of the causes of the suppression of body defences following thermal injury. The purpose of this study was to find out any abnormality of the postburn serum proteins by the comparison of burned and normal sera using immunoprecipitation in gel. The results of SDS-polyacrylamide gel electrophoresis, crossed immunoelectrophoresis, tandem crossed immunoelectrophoresis, and fused rocket immunoelectrophoresis showed that differing precipitation bands or peaks existed between burned and normal sera, and abnormal constituents with relatively low molecular weight were present in the burned serum.

Biochemical characterization of an antigen-specific suppressor T cell factor

We describe here the biochemical properties of suppressor T cell factor (TsF2) released from an inducible anti-idiotypic T cell hybridoma (C57BL/6 T cell x BW5147) which mediates antigen (keyhole limpet hemocyanin) specific and genetically (H-2b) restricted suppression of IgG plaque-forming cell responses. We examined the suppressive activity by in vitro functional assay in fractions of chromatography and in the materials eluted from gels of sodium dodecyl sulfate polyacrylamide and isoelectric focusing and determined the molecular weight(s) (22-37 kD) and the isoelectric point(s) (pH 6.0-6.1) of this secreted factor. Messenger RNA products of the hybridoma translated in the rabbit reticulocyte lysate system were similarly examined, and the functionally active molecule was seen to migrate to almost the similar molecular weight(s) (23-40 kD), and isoelectric point(s) (pH 5.5-6.2) range as those of secreted TsF. Moreover, the TsF activity was recovered from gel slice corresponding to the similar molecular weight range analyzed in sodium dodecyl sulfate polyacrylamide gel electrophoresis under reducing and nonreducing conditions. Thus, we speculate that this molecule is composed of a single chain, biologically active. Comparison of autoradiograms on in vitro translation products between activated and resting hybridomas by two-dimensional gel electrophoresis showed that the molecular weights and isoelectric points of two spots (28 kD, 5.7; 25 kD, 5.5) newly appearing or markedly enhanced after activation in the area with suppressor activity were concordant with the data on secreted TsF, suggesting that one of these two spots represents the functional molecule which causes antigen-specific and genetically restricted suppression of IgG responses.

Soluble factors in tolerance and contact sensitivity to 2,4-dinitro-fluorobenzene in mice. IX. A monoclonal T cell suppressor molecule is structurally and serologically related to the alpha/beta T cell receptor

Ts cells from mice tolerized with dinitrobenzene sulfonate produce a DNP-specific, MHC-restricted soluble suppressor factor (SSF) which regulates contact sensitivity to 2,4-dinitro-fluorobenzene. Previous studies have shown that the SSF-producing T cells and the soluble factor have the same hapten/MHC specificity suggesting that SSF may represent a secreted form of the Ts membrane receptor. The relationship between TCR proteins and SSF was investigated by examining the structural and serologic properties of a monoclonal DNP/H-2Kd-specific suppressor molecule produced by a Ts hybridoma. Reduction followed by alkylation abrogated the ability of the 3-10 molecule to inhibit transfer of contact sensitivity to 2,4-dinitro-fluorobenzene, indicating that intact disulfide bonds were a required structural property for suppression. Reduction of the 3-10 molecule followed by affinity chromatography on DNP-coupled Sepharose beads indicated that the 3-10 suppressor molecule is a dimer and that one of its chains binds to cell-free DNP. Serologic properties of the 3-10 molecule were examined by determining the ability of pan-reactive rabbit anti-TCR antibodies and anti-V beta 8 mAb KJ16.133 and F23.1 to adsorb suppressor activity from 3-10 culture supernatant and affinity purified 3-10 ascites material. All three reagents adsorbed the suppressor activity whereas control antibodies had no effect. When 3-10 material was passed through a F23.1-conjugated Sepharose affinity column, suppressor activity was recovered in the column eluate but not in the effluent fraction. When the 3-10 molecule was reduced and separated into its two chains (i.e., DNP-binding and non-DNP-binding chains), it was found that the anti-V beta 8 antibody F23.1-bound to the non-DNP-binding chain of the suppressor molecule. Collectively, these results indicate that the monoclonal 3-10 suppressor molecule is structurally similar to the alpha/beta TCR and suggest that the 3-10 molecule expresses a determinant encoded by the V beta 8 family of TCR genes. These results are consistent with our hypothesis that these suppressor molecules represent a secreted form of the TCR expressed on the surface of the DNP-specific Ts.

Modulation of Ig gene expression by Ig binding factors. Suppression of alpha-H chain and lambda-2-L chain mRNA accumulation in MOPC-315 by IgA-binding factor

Previous reports by a number of laboratories have shown that Ig-binding factors may play a role in the regulation of Ig production by B cells. Although numerous studies have addressed the specificity and biologic function of Ig-binding factors at the cellular level, little information is available regarding the mechanism whereby Ig-binding factor modulates Ig production by B cells at the molecular level. Herein we have examined the specificity and molecular mechanism of the suppression of IgA production mediated by IgA-binding factor. Using the IgA-secreting plasmacytoma, MOPC-315, as a target cell, we have demonstrated that: 1) IgA-binding factor binds to IgA, but not to IgG, IgM, or BSA; 2) IgA-binding factor can suppress proliferation as well as IgA production by MOPC-315; 3) soluble IgA, but not IgG or IgM can inhibit the action of IgA-binding factor; 4) suppression of Ig production by IgA-binding factor is maximal within 8 to 12 h after exposure to the factor and is reversible; 5) IgA-binding factor suppresses IgA production by selectively down-regulating synthesis of IgA H and L chain proteins; 6) IgA-binding factor selectively suppresses transcription of alpha-H chain and lambda-2-L chain genes; 7) IgA-binding factor suppresses accumulation of c-myc mRNA. These findings suggest that IgA-binding factor binds selectively to surface IgA on MOPC-315 and suppresses IgA production by down-regulating transcription of H and L chain genes. Suppression of MOPC-315 proliferation by IgA-binding factor may be related to the concomitant down-regulation of the expression of the c-myc gene. c-myc is deregulated in MOPC-315 by virtue of the reciprocal 15:12 chromosomal translocation present in MOPC-315 where the c-myc gene is translocated and rearranged into the alpha-H chain gene complex. Simultaneous suppression of the expression of c-myc and alpha-H chain genes suggests that these two genes may be coordinately modulated, in plasmacytomas, by IgA-binding factor.

Studies on suppressor factors produced by T-cell hybridomas. I. Characterization of antigen-specific suppressor factors

Antigen-specific and antigen-nonspecific suppressor T cells were generated when spleen cells prepared from C57BL/6J (H-2b) were incubated with trinitrophenylated polyacrylamide beads (TNP-PAA) in vitro. T hybridomas were prepared by fusion of spleen cells cultured with TNP-PAA for 4 days and the thymoma cell line BW5147. More than 100 hybridomas were generated, and 15 of them suppressed the anti-TNP PFC response of fresh spleen cells cultured with TNP-PAA. The suppression was antigen specific with three of these five hybridoma supernatants tested. Hybridomas that caused antigen-specific suppression secrete factors which bring about suppression of the anti-TNP PFC response by spleen cells cultured with TNP-PAA. These hybridoma supernatants which cause antigen-specific suppression typically depressed the anti-TNP PFC response by 60% while depressing anti-SRBC PFC response by only 10%. The antigen-specific suppressor factors were bound to a TNP-BGG column but not to a BGG column. The suppressor factors, purified by affinity chromatography on a TNP-BGG column, were bound to anti-I-Jb antibody.

An antigen-specific helper T cell hybridoma produces an antigen-specific suppressor inducer molecule with identical antigenic fine specificity. Implications for the antigen recognition and function of helper and suppressor inducer T cells

We have previously described a T cell hybridoma, A.1.1, that responds to specific Ag (P18, a synthetic polypeptide of defined sequence) in the context of I-Ad by producing lymphokines. Herein we report that this cell also releases, into culture supernatants and ascites fluid, an Ag-specific activity that functions in the induction of suppression of anti-SRBC PFC responses. This suppressive activity requires a) Ag-non-specific accessory molecules from a T suppressor inducer factor, b) Ly-2+ T cells in the assay cultures, and c) the specific Ag (P18) conjugated to the SRBC in the assay cultures. The specificity of the A.1.1-derived activity was demonstrated by the absence of suppression in cultures containing SRBC, BSA-SRBC, or conalbumin-SRBC rather than P18-SRBC. Further, the A.1.1-derived activity bound to, and could be eluted from, P18 but not conalbumin. Using a panel of synthetic variant peptides, we have mapped the critical residues in P18 required for Ag/I-Ad induced activation of A.1.1. These peptides were tested for their ability to act as targets for the A.1.1-derived suppressive activity when conjugated to SRBC and added to assay cultures. All peptides capable of stimulating the A.1.1 T cells to release lymphokines were similarly effective in the suppressor assay. Thus, the recognition of Ag by the T cells and by the T cell-derived activity appeared to be identical. The A.1.1-derived molecule was found to be capable of inducing L3T4- T cells to act as suppressor T cells following culture. These suppressor cells were active in inhibiting anti-SRBC responses in the absence of P18 and bore the Ly-2 surface marker. Thus, it is likely that the function of this Ag-specific molecule is to induce Ly-2+ suppressor T cells and thereby cause the inhibition of the response. This function is distinct from that normally associated with helper T cells and may shed new light on the possible relationship between the cell surface T cell receptor for Ag and Ag-specific T suppressor inducer molecules.

Induction of abortion in mice with a monoclonal antibody specific for suppressor T-lymphocyte molecules

A monoclonal antibody, mAb 14-30, which binds T-cell produced suppressor factors (TsF) was used to study the possibility that molecules produced by suppressor T-cells play a role in maintaining pregnancy, presumably by protecting the fetus from the maternal immune system. Female mice were injected with mAb 14-30 at various times after mating. Overall, only 14% of the expected 68% of the mated and treated females were pregnant at term. In addition, Western blots were used to demonstrate the presence of TsF in fetuses, placentae, uteri and spleen of pregnant animals and its presence only in the spleen of non-pregnant animals. These experiments help to confirm results that indicate the importance of immune suppressor factors in maintaining pregnancy and extend these previous observations to include suppressor T-cell molecules.

Lymphocyte proliferative responses to the purified Dermatophagoides farinae major allergen in untreated and hyposensitized atopic patients

We investigated the proliferative response of lymphocytes from mite-sensitive patients (RAST D.far greater than 3.5 PRU/ml) in the presence of the major allergen Der.f.I purified from Dermatophagoides farinae. Comparative studies were carried out with peripheral blood mononuclear cells from non-atopic donors (RAST = 0), and from patients undergoing hyposensitization treatment (5 to 24 months). According to Student's t-test, there was no significant difference in the Der.f.I-induced proliferation of peripheral blood mononuclear cells from normal donors, untreated atopic patients and hyposensitized patients. In conclusion, it was impossible to discriminate between normal donors, atopic patients and hyposensitized patients with regard to their circulating lymphocyte responses to the purified major allergen Der.f.I.

Suppressive substance produced by T cells from mice chronically infected with Trypanosoma cruzi. II. Partial biochemical characterization

Culture supernatants of splenic T cells from susceptible CBA mice chronically infected with Trypanosoma cruzi contain a suppressive substance which can inhibit the induction of delayed-type hypersensitivity (DTH) to a wide range of antigens. The suppressive substance is distinct from T. cruzi antigen inasmuch as the supernatant depleted of any residual T. cruzi antigen by an affinity column still retains the suppressive activity, whereas addition of T. cruzi antigens to control supernatant did not confer suppressive function. The suppressive supernatant does not contain detectable levels of IL-1, IL-2, IL-3, or IFN-gamma but a modest level of IL-1 and IL-2 inhibitory activities. However, both these inhibitory activities elute at a different position from the DTH suppressive activity on gel filtration. The DTH suppressive activity is heat labile (1 h, 56 degrees C), cryostable, but destroyed by trypsin treatment. It binds to ricin but not to lentil lectin. Sepharose 4B gel filtration and HPLC analysis in mild chaotropic agents (urea, ethylene glycol) demonstrate that the suppressive substance has an apparent Mr of 30 to 60 kDa, but full DTH-suppressive activity is retained only in an aggregated form.

Immune modulation by Coxiella burnetii: characterization of a phase I immunosuppressive complex differentially expressed among strains

Coxiella burnetii, the etiological agent of Q fever, possesses immunomodulatory activity which positively and negatively regulates host immune responses. We wish to determine the Coxiella strain differences and the chemical nature of cellular components suppressing lymphocyte responsiveness. The bacterial components responsible for the immunomodulatory activity are associated with phase I cells. In its natural state, the phase I cell-associated, immunosuppressive complex (ISC) was resistant to chemical and enzymatic treatment. The ISC was inactivated and rendered accessible by chloroform-methanol (CM) (4:1) extraction of phase I cells which produced a CM residue (CMRI) and CM extract (CME). The suppressive components in either CMRI or CME did not induce ISC activity in the host when injected separately. Reconstitution of the CMRI with CME prior to injection produced the same pathological reactions characteristic of phase I cells. The CMRI suppressive component was sensitive to alkali, acid, periodate, lysozyme, and neuraminidase, but resistant to lipase and protease. An active component of CMRI was attached to the cell matrix by disulphide bonds. The amphipathic, lipophilic, CME suppressive component was ubiquitously distributed in procaryotes and eukaryotes because ISC activity of CMRI was regained after association with reagent-grade lipids and different CMEs. The ISC was expressed by phase I strains with smooth lipopolysaccharide (LPS) but not by phase II strains with rough LPS. Phase I heart valve strains carrying significant amounts of rough LPS did not express all of the biological properties of the ISC. The LPS molecule induced immune enhancement without immunosuppression. Thus, expression of the ISC showed strain variation and may be under genetic control. The complete details of the chemical composition and active components of the ISC should prove useful for biological-response-modification studies.

Depression of cell-mediated immunity by tumour cell products: induction of resistance by immunotherapeutically active extracts of bovine ocular squamous cell carcinoma

Tumours produce substances that inhibit the expression of cell-mediated immunity, in the form of delayed-type hypersensitivity in mice. Phenol-saline extracts of bovine ocular squamous cell carcinoma (BOSCC) which have immunotherapeutic activity in cattle were able to immunize mice against this depressive effect. Such immunization was effective against products of BOSCC, a spontaneous rat tumour, three of four human tumour cell lines and (in other experiments) mouse tumours. Phenol-saline extracts of mouse tumour cell lines were immunogenic (protective against depression of delayed-type hypersensitivity) in mice. Fractions of BOSCC phenol-saline extracts which were immunotherapeutically active in cattle were generally also protective in mice. The protective activity was lost after treatment with proteinase K, and was present in the supernatant after precipitation with 55% ammonium sulphate. It was not affected by treatment with RNase or DNase or by heating to 50 degrees C for 2 h. It was present in gel filtration fractions with an apparent molecular weight of 10,000-37,000 daltons. The immunogenic factor in mice and the immunotherapeutic factor in cattle may be related to each other.

Murine IgA binding factors (IgA-BF) suppressing IgA production: characterization and target specificity of IgA-BF

Chemical and functional properties of IgA binding factor(s) (IgA-BF) from both murine Con A-activated spleen cells and Fc gamma R+, Fc alpha R+ T hybridoma cells (T2D4) were studied. IgA-BF produced from the cells after preculture with IgA were purified with IgA-Sepharose. Purified IgA-BF inhibited the binding of IgA to Fc alpha R+ L5178Y T lymphoma cells, and class-specifically suppressed in vitro IgA synthesis of the pokeweed mitogen (PWM)-stimulated murine spleen cells. Both IgA-specific suppressive activity and IgA binding activity of the factor(s) were co-fractionated between BSA and OVA in gel filtration analysis. SDS-PAGE analysis of IgA-BF biosynthetically labeled with [35S]methionine showed a specific band on 56,000. Suppressive activity of IgA-BF was absorbed with lentil-lectin-Sepharose and was eluted with 0.2 M alpha-methyl-D-mannoside. The suppressive activity obtained from T2D4 cells (H-2k) and BALB/c Con A blasts (H-2d) was absorbed with the corresponding anti-H-2 and anti-I-A column and recovered in the acid-eluate. The activity was not absorbed with the unrelated anti-H-2 column. Despite the presence of MHC products, IgA-BF from both cell sources equally suppressed IgA-specific responses of BALB/c (H-2d), C3H/He (H-2k), and C57BL/10 (H-2b) spleen cells. They also suppressed IgA production as well as IgA synthesis of PWM-stimulated culture of human peripheral blood lymphocytes without affecting IgM and IgG responses. Suppression of murine and human IgA responses both in mouse and human were mediated by the molecules having the same Ia products, suggesting that there is no MHC, as well as species restriction, for the interaction between IgA-BF and their target cells. IgA-specific suppressive activity was absorbed with human B blastoid cells bearing surface IgA (Dakiki) but not with those bearing surface IgG (CESS) or murine and human T cell line cells (BW5147, L5178Y, HPB-ALL, and MOLT4), indicating that IgA-BF interact with B cells bearing IgA to suppress their differentiation.

[Changes in nonspecific suppressor factors in the serum of gastric cancer patients after surgery and immunochemotherapy]

After curative surgery for gastric cancers judged macroscopically to be at stage 2 or 3, patients were divided into 4 groups by randomization. As the basic treatment, patients were given one-shot Mitomycin and Tegafur as maintenance therapy for 8 months (group A). PSK (group B), OK-432 (group C) or both PSK and OK-432 (group D) were added to the treatment of group A for 8 months. Sera were obtained from these groups of patients at 4 weeks and 3, 6, 9 and 12 months after surgery. In all of these groups, values of IAP increased slightly at 4 weeks but decreased at 3 months and were maintained at such a level by 12 months. On the other hand, suppressive effects of such sera on the blastogenesis of murine spleen cells in response to PHA varied among these group. In groups A and C, the suppressive effect of sera increased after surgery and was detected continuously by 12 months. In groups B and D, in contrast, the suppressive effect disappeared from 3 to 12 months. The rise and fall of such a suppressive effect of sera may reflect the mode of action of PSK.

Immune reactivity in cattle with ocular squamous cell carcinoma after intralesional BCG immunotherapy

Lymphocyte stimulation with Con A and specific immune reactivity to BCG (antibody formation to BCG and DTH reaction to PPD) were determined in BCG-treated, surgically treated and untreated cows with ocular squamous cell carcinoma. In tumor-bearing cows the Con A-induced proliferation of lymphocytes was reduced when compared to healthy controls. This suppression consisted of a reduced blastogenic response to Con A of lymphocytes from tumor-bearing cows, and the presence of a factor in the sera of these animals, as these sera suppressed the blastogenic response of lymphocytes from healthy cows. BCG had only a minor influence on the suppressive activity. Antibodies to BCG were demonstrated in 50% of the BCG-treated animals. The formation of antibodies was not influenced by intradermal injection of PPD of Mycobacterium bovis. Absorption of a BCG antibody containing serum with BOSCC tumor extracts did not reveal the existence of cross reacting antigens between BCG and BOSCC. Pretherapeutic and posttherapeutic Con A reactivity could not be correlated with clinical response. Of the 30 BCG treated cows 29 developed a positive DTH reaction to PPD. Correlation between clinical response and immune reactivity was seen only with regard to the DTH reaction to PPD: this reaction remained positive for a longer period after treatment in animals with a favorable clinical outcome than in nonresponding animals.