Evidence for a molecular complex consisting of Fyb/SLAP, SLP-76, Nck, VASP and WASP that links the actin cytoskeleton to Fcgamma receptor signalling during phagocytosis.

Phagocytosis by macrophages and neutrophils involves the spatial and temporal reorganisation of the actin-based cytoskeleton at sites of particle ingestion. Local polymerisation of actin filaments supports the protrusion of pseudopodia that eventually engulf the particle. Here we have investigated in detail the cytoskeletal events initiated upon engagement of Fc receptors in macrophages. Ena/vasodilator-stimulated phosphoprotein (VASP) proteins were recruited to phagosomes forming around opsonised particles in both primary and immortalised macrophages. Not only did the localisation of Ena/VASP proteins coincide, spatially and temporally, with the phagocytosis-induced reorganisation of actin filaments, but their recruitment to the phagocytic cup was required for the remodelling of the actin cytoskeleton, extension of pseudopodia and efficient particle internalisation. We also report that SLP-76, Vav and profilin were recruited to forming phagosomes. Upon induction of phagocytosis, a large molecular complex, consisting in part of Ena/VASP proteins, the Fyn-binding/SLP-76-associated protein (Fyb/SLAP), Src-homology-2 (SH2)-domain-containing leukocyte protein of 76 kDa (SLP-76), Nck, and the Wiskott-Aldrich syndrome protein (WASP), was formed. Our findings suggest that activation of Fcgamma receptors triggers two signalling events during phagocytosis: one through Fyb/SLAP that leads to recruitment of VASP and profilin; and another through Nck that promotes the recruitment of WASP. These converge to regulate actin polymerisation, controlling the assembly of actin structures that are essential for the process of phagocytosis.

Fyn-binding protein (Fyb)/SLP-76-associated protein (SLAP), Ena/vasodilator-stimulated phosphoprotein (VASP) proteins and the Arp2/3 complex link T cell receptor (TCR) signaling to the actin cytoskeleton.

T cell receptor (TCR)-driven activation of helper T cells induces a rapid polarization of their cytoskeleton towards bound antigen presenting cells (APCs). We have identified the Fyn- and SLP-76-associated protein Fyb/SLAP as a new ligand for Ena/ vasodilator-stimulated phosphoprotein (VASP) homology 1 (EVH1) domains. Upon TCR engagement, Fyb/SLAP localizes at the interface between T cells and anti-CD3-coated beads, where Evl, a member of the Ena/VASP family, Wiskott-Aldrich syndrome protein (WASP) and the Arp2/3 complex are also found. In addition, Fyb/SLAP is restricted to lamellipodia of spreading platelets. In activated T cells, Fyb/SLAP associates with Ena/VASP family proteins and is present within biochemical complexes containing WASP, Nck, and SLP-76. Inhibition of binding between Fyb/SLAP and Ena/VASP proteins or WASP and the Arp2/3 complex impairs TCR-dependent actin rearrangement, suggesting that these interactions play a key role in linking T cell signaling to remodeling of the actin cytoskeleton.

Characterization of clonally derived, spontaneously transformed bone marrow macrophage cell lines from lipopolysaccharide hyporesponsive LPS(d) and normal LPS(n) mice.

Six macrophage cell lines, each derived from a bone marrow macrophage colony grown in soft agar, were established by expansion of the macrophage clones in liquid culture until spontaneous transformation occurred. Four lines originated from the LPS(d) nonresponder mouse strain C3H/HeJ and two from the LPS(n) responder strain CBA/J. The cell lines adhered to plastic and glass surfaces and displayed typical macrophage functions such as phagocytosis and nonspecific esterase activity. Flow cytometry analyses showed that the lines expressed the macrophage surface markers CD11b, CD13, CD32/16, F4/80, and BM8 constitutively. A moderate expression of the adhesion receptor CD11a, but only a very low expression of its ligand CD54, was observed. A minor fraction of the cells in each line constitutively expressed MHC class II antigen, and its expression could be up-regulated in each cell line by treatment with interferon-gamma (IFN-gamma). Secretion of the inflammatory mediators nitric oxide (NO), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-alpha) after induction by three bacterial derivatives, heat-killed Salmonella typhimurium (HKS), lipopolysaccharide (LPS), and the Mycoplasma fermentans-derived amphiphilic lipid MDHM, were examined in detail. Not only did the lines differ in the amounts of mediators secreted in response to any one stimulus, but the doses of MDHM or LPS required for 50% maximal induction of NO varied up to 10-fold among the four LPS(d) cell lines, suggesting considerable functional heterogeneity between the clones. Secretion of large amounts of TNF-alpha was induced in all the cell lines by HKS. Although it could be shown that exogenously added TNF-alpha acted synergistically with IFN-gamma to induce NO release from the cell lines, an autocrine role for TNF-alpha during HKS-IFN-gamma induction of NO synthesis could not be substantiated. Neutralization of TNF-alpha with a specific antibody completely blocked NO induction by exogenous TNF-alpha but did not abrogate NO release either by HKS-IFN-gamma-induced cells or by macrophages treated with supernatant from an HKS-IFN-gamma-activated cell line. These results indicate that the clones are arrested in distinct stages of differentiation and retain some properties of normal untransformed macrophages. They should be helpful tools for investigations into macrophage function.

7-O-acetyl-GD3 in human T-lymphocytes is detected by a specific T-cell-activating monoclonal antibody.

The monoclonal antibody U5, which is a potent inducer of proliferation in human T-cells, was found to bind to an alkali-sensitive derivative of ganglioside GD3. Using immunochemical and spectroscopic methods, the structure of the U5 antigen was determined as 7-O-acetyl-GD3. The antibody U5 did not react with 9-O-acetyl-GD3 and bound severalfold more stronger to 7-O-acetyl-GD3 than to GD3. U5 is the first antibody known to detect preferentially 7-O-acetyl-GD3. Flow cytometric analysis showed that each major class of human leukocytes contained a significant fraction of cells binding the U5 antibody.

Surface expression of Forssman glycosphingolipid antigen on murine bone marrow-derived macrophages is subject to both temporal and population-specific regulation and is modulated by IL-4 and IL-6.

The Forssman glycolipid antigen (Fo) has been shown to be a differentiation marker for mouse macrophages both in vivo and in vitro. In order to determine whether or not there is a relationship between stage of differentiation and Fo expression, we have analyzed the kinetics of Fo expression during the growth of cultured mouse bone marrow-derived macrophages (BMDM). BMDM were grown in serum free medium to avoid the possible influence of undefined serum factors. In this medium they could be maintained over a period of up to 20 days with cell yields comparable to those obtained with serum-supplemented media. Fo antigen was assayed with a specific antibody using both a whole cell ELISA and immunocytochemical staining of cells grown on slides. With increasing age in culture, BMDM showed a gradual quantitative increase in Fo expression and parallel increase in the Fo+ BMDM fraction from about 10% Fo+ cells on the 10th day of culture to a maximum of 50%-60% Fo+ cells between the 17th and 19th days. The temporal control over the development of the Fo+ cell fraction was intrinsic to BMDM maturation but was specific for Fo. During the same time period expression of MHC class II (Ia) remained consistently low, whereas expression of both Mac-1 (C3bR) and the macrophage-specific marker ER-BMDM-1 was always high. The interleukins IL-4 and especially IL-6 induced a premature expression of Fo at earlier stages of BMDM culture, but neither could promote further Fo expression once the intrinsically occurring maximum had been reached. No evidence in support of an autocrine regulation of Fo expression by IL-6 could be obtained, nor could a connection between cell cycle status and Fo expression be established. These data provide further evidence that Fo is a temporally regulated differentiation marker for a mouse macrophage subpopulation and for modulation of its expression by lymphokines.

CD22 antigen: biosynthesis, glycosylation and surface expression of a B lymphocyte protein involved in B cell activation and adhesion.

The CD22 antigen, although present in the cytoplasm of early and immature B cells, first appears on the cell surface of mature B lymphocytes. The phenotypic patterns and some functional properties of the surface-expressed CD22 antigen are well described, but little is known about its molecular structure. We have therefore investigated the relationship of the two CD22 glycoproteins (140/130 kd), and the influence of their complex N-glycosylation on surface expression and antibody recognition. Comparative peptide mapping of the 100 and 80 kd protein cores, obtained by endoglycosidase F treatment, revealed a common structure shared by both protein cores. In pulse-chase experiments the mature glycoproteins originated from two separate precursor molecules, indicating that the two proteins may be generated by different RNA processing. In cell lysates a CD22 specific polyclonal anti-serum recognized both molecules the size of the protein cores and glycosylated CD22 molecules, whereas in membrane preparations only the glycosylated forms were detected. The CD22 mAb HD39 reacted exclusively with the glycoprotein froms in either cellular preparation. The influence of glycosylation on surface expression and epitope recognition was investigated in more detail by applying various inhibitors of the glycosylation pathway. 1-Deoxymannojirimycin and Swainsonine, which block glycosylation at the high-mannose and hybrid-type stages respectively, modulated the CD22 antigen but did not alter its surface expression. Tunicamycin blocked de novo glycosylation and led to reduced surface recognition of the CD22 antigen. Together, these results suggested that comparatively simple oligosaccharide structures of high-mannose type are sufficient for surface expression of the CD22 antigen and for epitope recognition by mAb HD39. It is most likely that glycosylation is required to stabilize epitopes in the protein moiety recognized by CD22 mAb. Finally, we demonstrated the presence of glycosylated, cytoplasmic CD22 antigen in CD22 surface negative B-lineage ALL cells. This finding led us to conclude that complex glycosylation does not provide the determining signal for the switch from cytoplasmic to surface expression of the CD22 antigen.

Neutral glycosphingolipids of the globo-series characterize activation stages corresponding to germinal center B cells.

The neutral glycosphingolipid (GSL) globotriaosylceramide (Gb3) of the globo-series was recently defined as the CD77 antigen. This B cell-associated antigen is characterized by its specific expression on germinal center B cells. In order to study the potential relation of the CD77 antigen and other GSLs to B cell activation we have performed a comprehensive analysis of the synthesis and expression of neutral GSL in tonsillar B lymphocytes. Monoglycosylceramide (GL1) and lactosylceramide (LacCer) comprised the largest portion of GSL in tonsillar B lymphocytes as detected by HPLC analysis. GSLs of the globo-series Gb3 and globotetraosylceramide (Gb4), were found in smaller amounts. Since other GSLs, like gangliotriaosylceramide (Gg3) and gangliotetraosylceramide (Gg4), could only be detected using highly sensitive antibody reactions, we assume that these GSLs occur in B cells only in minor amounts. When tonsillar B cells were density fractionated on Percoll, the light density cells, which correspond to activated cells, contained and expressed more of both globo-GSLs than cells in the higher density fraction. When the dense fraction of tonsillar B cells was activated in vitro by anti-mu/BCGF, synthesis of GL1, LacCer, Gb3, and Gb4 was biphasic, with maxima at 12 and 84 h. Surface expression of the CD77 antigen on the denser cells was strongly induced by anti-mu/BCGF during the first 24 h of cultivation followed by a rapid decline thereafter, mimicking synthesis. PMA treatment of this cell fraction caused an even stronger expression of the CD77 antigen, which lasted over 48 h of cultivation.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunohistochemical localization of Forssman glycosphingolipid-positive macrophages and reticular cells in murine lymphoid tissue.

Forssman (Fo) glycolipid antigen, as detected by a monoclonal antibody (mAb), is expressed by a subpopulation of murine macrophages in the spleen and peripheral lymph nodes. The histological distribution of Fo antigen in spleen and lymph nodes was studied by immunostaining of cryosections, and was compared with the staining pattern of four other mAbs known to recognize macrophage subpopulations: F4/80, Mac-1, MOMA-1, and ERTR-9. Fo+ macrophages were found exclusively in the red pulp of the spleen and the medulla of inguinal and axial lymph nodes. Macrophages in the other lymphoid organs were Fo-. Besides macrophages, reticular cells in T-dependent areas of spleen and lymph nodes were Fo+. Attempts to grow colonies of Fo+ macrophages from either bone marrow or spleen precursors were negative. While the usual number of F4/80+ colonies was obtained, only a few, small clusters of Fo+ macrophages were formed, which speaks against an early commitment of precursors to express Fo.

An assay for growth of mouse bone marrow cells in microtiter liquid culture using the tetrazolium salt MTT, and its application to studies of myelopoiesis.

Mouse bone marrow cells were grown in liquid culture in microtiter plates in the presence of different colony-stimulating factors (CSF). Growth was assayed using the tetrazolium salt MTT, which is reduced in the mitochondria of viable cells to a water-insoluble blue formazan dye. Two technical problems have limited the use of this assay: the solubilization of the dye crystals and the necessity to acidify the phenol red in the culture medium. Both could be solved here by the use of a developing solution of 5% formic acid in isopropanol. Using manual mixing combined with a short sonication by floating the plates in a sonic bath, the crystals were dissolved within minutes. There was no flocculation of protein, even using medium with 20% serum. The color remained stable for at least 4 h. This enabled the semi-automatic measurement of large numbers of cultures directly in the microtiter plates. Growth and differentiation of myelopoietic precursor cells in the liquid cultures was shown to be comparable to that in soft agar. Cell growth was CSF-dependent. The calculated cell yield per colony forming cell (CFC) seeded was within the range of the average cell number per colony found in soft agar, and the spectrum of mature cells obtained reflected the type of CSF used as stimulus. Using the combined culture and assay systems, it was possible to perform detailed kinetic studies of myelopoiesis. This technique should be useful for studying the mechanisms of action of pharmacological modulators of myelopoiesis.

Large scale production and purification of human IL-2 from buffy coat lymphocytes stimulated with 12-O-tetradecanoylphorbol 13-acetate and calcium ionophore A23187.

Methods for the production of high titers of interleukin-2 (IL-2) from human buffy coat lymphocytes, and subsequent purification of the IL-2 are described. 50 buffy coats containing 1 X 10(11) leukocytes were first depleted of erythrocytes by batchwise leukapheresis using a Haemonetics model 15 blood wash centrifuge. Further lymphocyte enrichment was achieved using a one-step sedimentation in the presence of hydroxyethyl starch, which produced suspensions of more than 90% lymphocytes. This degree of lymphocyte purity was important since phagocytes were inhibitory to 12-O-tetradecanoylphorbol 13-acetate/calcium ionophore (TPA/A23187)-induced IL-2 production when their concentration exceeded 15% of the total cells. Cell culture was performed in stirred fermenters. Using TPA/A23187 induction, up to 500 micrograms of IL-2 per liter were produced. The IL-2 was purified by absorption from the supernatants onto controlled pore glass and elution with 50% ethylene glycol, followed by Fractogel chromatography, and then preparative high-performance liquid chromatography (HPLC) using an RP-6 column and elution with a gradient of n-propanol. A final HPLC rechromatography step using an analytical RP-6 column gave a homogeneous preparation with specific activity of 1.2 X 10(7) U/mg and a recovery from the starting supernatant of 22%.

Intralymphatic interleukin-2 treatment of a hemophiliac AIDS patient with defective interleukin-2 production.

To improve immune functions in an interleukin-2 (IL-2) deficient hemophiliac AIDS patient suffering from severe Pneumocystis carinii pneumonia, treatment with IL-2 was started in addition to standard antimicrobial therapy. Highly purified IL-2 was administered subcutaneously and then repeatedly intralymphatically in a manner similar to pedal lymphography. No toxicity was observed. The patient temporarily improved clinically as well as with regard to immunological functions. Particularly the in vitro response to phytohemagglutinin (PHA) could partly be restored, and skin tests revealed improved response to recall antigens. These findings indicate that IL-2 can be administered safely and effectively by the intralymphatic route and may--in addition to antibiotics--be of value in AIDS patients with severe opportunistic infections.

Intralymphatic interleukin 2 treatment in patients with acquired immunodeficiency syndrome: preliminary experience in three cases.

Patients with opportunistic infections during the course of acquired immunodeficiency syndrome (AIDS) were analyzed for cellular immune functions and found to be severely immunocompromised. In particular, interleukin 2 (IL 2) production appeared to be defect not only qualitatively but also quantitatively. In some of these patients, exogenous IL 2 improved immune response in vitro. Intralymphatically administered highly purified natural IL 2 was given repeatedly (over a time period of ten days) to three of these patients. In two cases, such a treatment course was repeated later. Clinical response - at least in some patients - appeared to be of temporary benefit. Shortly after termination of IL 2 application in two patients an increase of lectin responsiveness as well as improved reactivity in skin testing was noted, encouraging further exploration of IL 2 as an immunostimulatory drug in AIDS patients.

Constitutive production of colony-stimulating factor by mouse lymphoma cell lines is correlated with granulocytosis in vivo.

The mouse lymphoma cell line Eb, its highly metastasizing variant ESb, and an unrelated metastasizing tumor MDAY-D2, were shown to produce colony-stimulating factor (CSF) constitutively both in vitro and in vivo in ascites. For each tumor, the amounts of CSF produced on a per-cell basis in vitro and in vivo were similar. The findings were substantiated using two different methods for CSF determination, a colony assay and an isotope incorporation test. Elevated levels of CSF in serum of mice with tumors were also found. Examination of blood from tumor-bearing mice revealed that whereas total leukocyte counts remained within the normal range, all three tumors caused a reversal of the normal neutrophil-lymphocyte ratio. The severity of the reversal correlated with the propensity of the tumor to elevate serum CSF rather than with in vitro CSF-producing capacity. Thus, whereas production of CSF in vivo was not related to the ability of the tumors to metastasize, it could be causative in creating an imbalance in normal hematopoiesis.

Calcium ionophore A 23 187 in the presence of phorbol ester PMA: a potent inducer of interleukin 2 and interferon-gamma synthesis by human blood cells.

Cultures of human blood mononuclear cells incubated with the calcium ionophore A 23 187 in the presence of the tumor promoter phorbol 12-myristate-13-acetate (PMA) produced 5-10 times more of the lymphokines interleukin 2 (IL 2) and interferon-gamma (IFN-gamma) than cultures which were stimulated with other combinations of inducing agents and PMA. Especially at low protein concentrations, the amount of ionophore which is necessary to induce maximal quantities of both lymphokines was determined by the protein content of the culture medium. The synthesis of the two lymphokines was inhibited by low doses of Mn++ which competes with Ca++ for binding to the ionophore. This suggests the importance of Ca++ in the induction process. The synthesis rates of IL 2 were maximal 10-12 h, and those of IFN-gamma 20-40 h after induction. Maximal titers of IL 2 were detected 48 h after the addition of A 23187 and PMA to the cultures, and the highest IFN-gamma levels 12-24 h later.

Induction of lymphokine synthesis in peripheral blood mononuclear cells with phorbol ester and calcium ionophore allows precise measurement of individual variations in capacity to produce IL 2.

Absolute capacity for IL2 production by human peripheral blood mononuclear cells (PBMC) was studied using 12-O-tetradecanoylphorbol 13-acetate (TPA) and calcium ionophore A23187, which act synergistically, to induce lymphokine synthesis. Culture parameters were optimized for the TPA/A23187 stimulation such that maximal IL2 titers were produced with a high degree of reproducibility. Thus, using a synthetic medium, TPA/A23187 at 20/50ng/ml respectively, and a cell concentration of 2.5 X 10(6)/ml, IL2 titers in the cultures increased linearly over a period of 96h, reaching values at least 15-fold higher than with lectin stimulation. This allowed for determinations of IL2 synthetic capacity in individual blood samples. Large fluctuations in normal IL2 production (range 1775-10654 BRMP U/ml at 48h) were observed among 23 normal persons. A statistically significant lower IL2 productive capacity was observed in the age group above 40 as compared to those under 40. The lower rates of IL2 synthesis in a group of patients with Hodgkin's disease was seen only among those who had undergone immunosuppressive therapy; newly diagnosed cases fell within the normal range.

Glycosphingolipids of the globo-series are associated with the monocytic lineage of human myeloid cells.

Neutral glycosphingolipids (neutral GSLs) of the human myeloid leukemia cell lines ML-2, ML-3, HL-60 and THP-1-0 were metabolically labeled with [3H]galactose and [3H]glucosamine, and analyzed by high-performance liquid chromatography. They were compared with unlabeled neutral GSLs from purified human granulocytes and monocytes. Neutral GSLs were identified by retention times and the structures were further confirmed by degradation with specific exoglycosidases. Two neutral GSLs of the globoseries, globotetraosylceramide and globotriaosylceramide were found in monocytes and the monoblastic leukemia line THP-1-0. The leukemia-derived cell-lines, ML-3 and HL-60, representing successively earlier stages of myeloid differentiation, contained respectively less neutral GSLs of the globoseries and an increasing proportion of (neo)lacto neutral GSLs. Granulocytes and the cell line ML-2 contained almost exclusively neutral GSLs of the (neo)lacto series.

In vivo effects of interleukin 2 on lymphocyte subpopulations in a patient with a combined immunodeficiency.

This report describes a clinical trial with Interleukin 2 (IL-2) on a 17-month old male child with combined immunodeficiency (Nezelof's syndrome). IL-2 was prepared from conditioned media of phytohemagglutinin-stimulated leukocytes from buffy coats. The purification of IL-2 involved chromatography on Matrex Blue A sepharose and gel filtration chromatography. The preparation was free of macrophage cytotoxicity factor, macrophage migration inhibition factor and colony-stimulating factor. It contained negligible activity of interferon-gamma. IL-2 activity was adjusted to 1600 U/ml, which corresponds to about 0.8 micrograms homogeneous IL-2/ml. The patient was treated over a 50-day period with a total dose of 20,000 U IL-2, which was injected subcutaneously. IL-2 was well tolerated. Within 3 weeks, the treatment led to a normalization of a lymphocytosis which had prevailed for the previous 3 months. A pronounced eosinophilia also improved but did not reach normal levels. The most striking effect was a normalization of the OKT4+/OKT8+ ratio with a concomitant relative increase in OKT3+ cells in the peripheral blood. No effects were seen on E rosette formation, B cell counts or serum Ig levels. Also NK or ADCC activity remained high, as before the treatment. Infectious episodes and requirement for antibiotic treatment were less frequent during IL-2 therapy. Some effects of IL-2 were transient, e.g., the counts of OKT4+ and OKT3+ cells which returned to pathological values a few weeks after the treatment was discontinued.

The glycosphingolipid globoside as a serological marker on cytolytic T lymphocyte precursors and alloantigen-responsive proliferating T lymphocytes in murine spleen.

Biochemical analyses of murine lymphocytes have shown that the glycosphingolipid globoside (Glo) is present exclusively on alloantigen-stimulated murine T lymphocytes (Gruner, K. R., Van Eijk, R. V. W. and Mühlradt, P. F., Biochemistry 1981. 20: 4518). An anti-Glo antibody has now been raised in rabbits immunized with purified antigen. Most activity was recovered in the IgM fraction. The specificity of the antibody was ascertained in an enzyme-linked immunosorbent assay with purified glycosphingolipids bound to the solid phase. In antibody-dependent complement lysis experiments the anti-Glo eliminated about 20% of nylon wool-nonadherent splenic T cells of CBA/J mice. To determine the functional identity of these Glo+ cells, the effects of Glo+ cell elimination on mitogen stimulation with concanavalin A and lipopolysaccharide, as well as the effects on the mixed lymphocyte culture (MLC) reaction and cell-mediated lympholysis with mitomycin-treated DBA/2 splenocytes as stimulator cells were studied. Whereas lipopolysaccharide stimulation was not affected by elimination of Glo+ cells, there was a slight inhibitory effect on the concanavalin A stimulation, and a severe inhibition of the MLC reaction and the generation of H-2d-specific cytolytic T lymphocytes. Addition of interleukin 2 increased the MLC reaction, but interleukin 2-saturated cultures were also severely inhibited by anti-Glo and complement treatment. Combined treatment with anti-Glo and anti-Lyt-1 or anti-Lyt-2 antibodies, and determination of cytolytic T lymphocyte precursor frequencies in limiting dilution cultures after Glo+ cell elimination showed that a large proportion of T cells proliferating in a primary MLC are Lyt-1+,2+,3+Glo+, whereas in secondary MLC they are Lyt-1+,2-,3-,Glo+. Fifty % of the cytolytic T lymphocyte precursors in primary as well as secondary MLC are Glo+. The Glo marker is lost upon differentiation to cytolytic T lymphocyte effector cells. It is discussed herein that Glo is a marker for alloantigen-stimulated precursor T lymphocytes of both helper and cytolytic T cells.

Purification of the T lymphocyte growth factor interleukin-2 from culture media of human peripheral blood leukocytes (buffy coats).

Interleukin 2 was purified 100 000-fold to apparent homogeneity from the supernatants of mitogen-stimulated human blood leukocytes. A sequence of three purification steps was used: affinity chromatography on the bound dye cibacron blue, gel filtration on Ultrogel AcA44, and reversed-phase high-performance liquid chromatography on hexyl phase. The resulting interleukin 2 had a specific activity of 2 X 10(6) U/mg protein, and was free of pyrogenicity in the rabbit test. The final purification product showed two bands in sodium dodecyl sulfate/polyacrylamide gels with apparent molecular masses of 15 kDa and 17 kDa respectively. Both bands were biologically active.

Interleukin-1-like activity constitutively generated by Hodgkin derived cell lines. I. Measurement in a human lymphocyte co-stimulator assay.

Culture supernatants (CS) from Hodgkin derived cell lines have previously been shown to contain colony stimulating activity (CSF) for human cord blood cells, fetal bone marrow and fetal liver cells. In this study 3-day CS from four Hodgkin lines (L428, L538, L540, L591) and two sublines (L428KS, L428KSA) were examined for interleukin (IL) activity. None of the tested CS supported the growth of an IL-2 dependent murine T-cell line, suggesting that the Hodgkin lines do not produce significant amounts of IL-2. When crude 3-day CS from the various lines were assayed for IL-1-activity in the conventional murine thymocyte costimulator assay no or only borderline IL-1-activity was detectable. However, concentrated CS from L428KS exhibited IL-1-activity also in this assay as did lipopolysaccharide (LPS) induced human IL-1. Surprisingly, crude 3-day CS from all Hodgkin cell lines were capable of fully replacing the accessory cell requirement in ConA-induced lymphoproliferation assays of heavily monocyte-depleted human blood lymphocytes. The monocyte-depleted lymphocyte populations were obtained by 1 X g sedimentation at a sedimentation rate of 30.2 to 38.8 mm/hr (fraction IIIa and IIIb). These cells responded poorly to the T-cell mitogen ConA at 10 micrograms/ml and produced no IL-2. Addition of irradiated, autologous monocytes or of CS from the various Hodgkin cell lines quantitatively restored the ConA responsiveness and induced significant IL-2 production in the monocyte-depleted lymphocyte population, suggesting that Hodgkin lines constitutively secrete IL-1 or IL-1-like activity. A preliminary biochemical characterization (heat and pH stability, molecular weight range of 13-24 KD) supports the notion that the accessory cell replacing activity present in CS of Hodgkin cell lines is a type of human IL-1.