HLA-A2.1-restricted T cells react to SEREX-defined tumor antigen CML66L and are suppressed by CD4+CD25+ regulatory T cells.

The question of whether T cell responses to SEREX-defined tumor antigens are under regulation of naturally occurring CD4+CD25+ regulatory T cells (nTreg cells) has not been answered. To address this issue, we first identified an HLA-A2.1-restricted T cell antigen epitope of SEREX-identified tumor antigen CML66L, 66Pa. The HLA-A2.1/66Pa peptide complex in vitro stimulated the in vivo-primed T cells as shown by increased T cell proliferation, higher secretion of the T cell cytokine interferon-gamma (IFN-gamma), increased production of intracellular IFN-gamma in CD8+ T cells, and higher T cell-mediated cytotoxicities of CML66L+ human tumor cells. This suggests that CML66L elicits T cell immune responses. We also developed a novel internal reference epitope for identification of T cell epitopes by construction of chimeric CML66L containing myeloid antigen proteinase 3 epitope Pr1 as a control. Finally, we found that nTreg cells regulates T cell responses to 66Pa, and that depletion of nTreg cells via a pro-apoptotic protein Bax-dependent mechanism enhances polyclonal T cell responses to 66Pa. These findings provide new insights into the T cell participation in SEREX-defined anti-tumor immune responses and novel direction in enhancement of anti-leukemia immunotherapy by modulation of homeostasis of nTreg cells.

Immunization against MUC18/MCAM, a novel antigen that drives melanoma invasion and metastasis.

Melanoma patients with metastases have a very low survival rate and limited treatment options. Therefore, the targeting of melanoma cells when they begin to invade and metastasize would be beneficial. An adhesion molecule that is upregulated at the vertical growth phase is the melanoma cell adhesion molecule (MCAM/MUC18). MUC18 is expressed in late primary and metastatic melanoma with little or no expression on normal melanocytes. We utilized the alphavirus-based DNA plasmid, SINCp, encoding murine MUC18 (SINCp c-muMUC18) for vaccination against B16F10 murine melanoma cells expressing murine MUC18. This vaccine effectively protected mice from lethal challenges with melanoma-expressing murine MUC18 in both primary and metastatic tumor models. Vaccination against MUC18 elicited effective humoral and CD8+ T-cell immune responses against melanoma. We propose that targeting molecules important in tumor invasion may be useful in the design of future strategies for the prevention and treatment of melanoma.

DNA vaccination against neu reduces breast cancer incidence and metastasis in mice.

The gene for HER2/neu is overexpressed in 30-40% of breast and ovarian cancers, and this overexpression correlates with increased metastasis and poor prognosis. The HER2/neu gene product, a transmembrane protein kinase member of the EGF receptor family, has significant potential as a tumor antigen for vaccination. We inserted the sequence for neu into a novel plasmid called ELVIS containing a Sindbis virus replicon that reproduces multiple copies of mRNA. Mice vaccinated one time intramuscularly demonstrated a strong antibody response against A2L2, a murine breast cancer cell line transfected to express neu. Vaccinated mice challenged in the mammary fatpad with A2L2 had reduced tumor incidence and reduced tumor mass compared to mice challenged with tumor cells lacking the neu insert. Intradermal vaccination was also protective and required 80% less plasmid for a similar level of protection. Vaccination reduced the incidence of lung metastasis from mammary fatpad tumors and reduced the number of lung metastases resulting from intravenous injection of A2L2 cells. Cytotoxic T lymphocytes cultures of immune spleen cells with P815-neu cells produced high levels of interferon-gamma indicating an antigen-specific Th1-type immune response resulting from the vaccination. In a spontaneous breast tumor model using neu transgenic mice, vaccination with ELVIS-neu protected against development of spontaneous breast tumors. Our preclinical data indicate that therapeutic vaccination of patients with ELVIS-neu may reduce metastasis from HER2/neu-expressing breast and ovarian tumors.

Quantitative and bioluminescent assay to measure efficacy of conventional and DNA vaccinations against Helicobacter pylori.

Vaccination against Helicobacter pylori using DNA sequences encoding Urease A and B subunits was compared to immunization with urease antigen and MTP-PE in a liposome formulation. To determine the effectiveness of a vaccine against H. pylori in a mouse model it is essential to quantify the number of H. pylori remaining in the stomachs following challenge with an inoculum of live bacteria. Culture assays and enzymatic assays produce inconsistent results often unsuitable to conclude if vaccine candidates are protective. To overcome this problem, we developed two assays: 1) a competitive quantitative PCR using a colorimetric readout and 2) a non-competitive direct quantitative PCR using a highly sensitive bioluminescent readout. The competitive PCR requires coamplification of a segment of the urease C sequence and an internal control standard in a competitive manner using a single set of primers. PCR products were quantified colorimetrically by an enzyme-linked immunosorbent assay and compared with known quantities of the internal control standard added to the PCR reaction. The highly sensitive, bioluminescent assay measures the amplified DNA directly using a flash-type luminescent tag and a specific probe. The Sydney strain of H. pylori was used for the mouse infection model. Quantification of H. pylori by either the bioluminescent assay or the competitive PCR was reliable, specific and sensitive compared to quantitative growth assays which often gave false results. The bioluminescent assay was much more sensitive and less labor/time intensive than the competitive PCR. The bioluminescent assay was able to quantitate as few as 100 bacteria, while the competitive assay could not detect less than 10(3) bacteria per mouse stomach. Quantification of H. pylori by bioluminescent assay was superior to the competitive assay and may be used for research applications, such as the development of vaccines, pathogenesis of gastric disease and monitoring of antibiotic treatment.

Quantitation of Helicobacter pylori in the stomach using quantitative polymerase chain reaction assays.

BACKGROUND: The density of Helicobacter pylori is thought to correlate with the degree of inflammation and thus indirectly with the outcome of the infection. Rapid quantitative assays of H. pylori in gastric or duodenal mucosa are lacking. The aim was to develop quantitative assays using the polymerase chain reaction to assess the quantity of H. pylori in the gastric mucosa. METHODS: Competitive PCR was based on coamplification of a segment of the ureC sequence and an internal control using a single set of primers. PCR products were quantified colorimetrically by an enzyme-linked immunosorbent assay and compared with known quantities of the internal control standard added to the PCR reaction. The highly sensitive, noncompetitive PCR assay does not use coamplification and measures the amplified DNA sequence using a flash-type luminescent tag and a specific probe. The mouse infected model using H. pylori strain SS-1 was used to develop the assays. RESULTS: Quantification of H. pylori using either the competitive or noncompetitive PCR was reliable, highly sensitive and specific. CONCLUSIONS: The ability to rapidly quantitate H. pylori from gastric mucosa should be useful to investigate the role of H. pylori density and infection outcome, as well as to monitor the effectiveness of antibiotic treatment or vaccines against H. pylori.

Immunoliposomes containing antibodies to costimulatory molecules as adjuvants for HIV subunit vaccines.

Immunoliposomes containing monoclonal antibodies (MAbs) to the costimulatory molecules CD28 and CTLA4 and their counterreceptors B7-1 (CD80) and B7-2 (CD86) were evaluated for the ability to increase the immune response to recombinant envelope protein rgp120 of the MN strain of human immunodeficiency virus type 1 (HIV-1) during vaccination. MAbs were attached to rgp120-containing liposomes via a biotin-avidin-biotin bridge. Mice vaccinated with immunoliposomes were found to have a strong delayed-type hypersensitivity (DTH) response to the weakly immunogenic gp120 that was dependent on the presence of the MAbs. However, this vaccination protocol did not induce humoral immunity. The DTH response was not accompanied by increased production of interferon gamma (IFN-gamma) or interleukin 4 (IL-4), implying that the primary cellular interaction was between the immunoliposomes and cells of the reticuloendothelial system and not helper T (Th) cells. This strategy of incorporating antibodies to costimulatory molecules on the surface of antigen-containing particulates, such as liposomes or microspheres, can be used to increase DTH immune responses to protein or peptide vaccines.

Development of a murine model of Helicobacter pylori infection.

BACKGROUND: A murine model for Helicobacter pylori infection could facilitate vaccine development. This study was designed to determine the effect of various conditions of dose, frequency of administration, and fasting on H. pylori infection of mice. MATERIALS AND METHODS: Balb/c and C3H/HeN mice were inoculated orogastrically with clinical isolates of H. pylori grown in liquid culture. At 2-week intervals, the stomachs were removed for secondary culture on horse blood agar and for histological analysis. H. pylori from secondary cultures or homogenized stomach tissue from infected mice was inoculated a second time in naïve animals. RESULTS: H. pylori was cultured with high frequency only from the stomachs of C3H/HeN mice. Fasting the mice and increasing the number of organisms inoculated did not increase the rate of infection. Histological analysis detected no inflammation, but mucus depletion and erosion were present in the stomachs of C3H/HeN mice. H. pylori organisms were not observed. Secondary cultures of H. pylori or homogenized infected stomach tissue did not cause infection when inoculated in naïve mice. CONCLUSIONS: Clinical isolates of H. pylori transiently infect C3H/HeN mice. This murine model is suitable for testing oral vaccines. Effective vaccination against H. pylori could prevent transient infection and reduce subsequent gastritis.

Cytokine-containing liposomes as vaccine adjuvants.

The ability of cytokines to regulate and augment an immune response makes them likely agents to be included in vaccines. The systemic use of cytokines as vaccine adjuvants has been hampered by toxicity at effective doses. More precise delivery of cytokines and immunogen can be achieved through the use of microparticle carriers such as liposomes. Several cytokines, including IL-2, IL-7, IL-6 and IFN-gamma have been shown to increase the adjuvant activity of liposomes. It may be possible to use certain cytokines to induce immunoglobulin production, others to induce cytotoxic T lymphocytes (CTL) and still others to promote IgA production at mucosal surfaces. An alternative to liposomes containing cytokines may be liposomes containing cytokine-inducing adjuvants such as MTPPE, MPL and QS21. This approach may produce undesirable immunomodulators as well as beneficial cytokines.

Cytokine-containing liposomes as adjuvants for HIV subunit vaccines.

Dehydration-rehydration liposome vesicles (DRVs) containing various cytokines were evaluated for their ability to induce delayed-type hypersensitivity (DTH) and humoral immunity to the recombinant envelope protein rgp120 of the MN strain of human immunodeficiency virus type 1 (HIV-1). The DRVs trapped approximately 25% of the radiolabeled cytokines and approximately 17% of the radiolabeled rgp120 that were added. The level of trapping was greater than the aqueous volume of the DRVs, indicating association of the proteins with the lipid bilayer. Flow cytometric analysis using antibody to rgp120 or the V3 loop of rgp120 showed the diameter of the DRVs to be 2-7.5 microns. Transmission electron microscopy confirmed the heterogeneity in size of the DRVs and revealed morphological heterogeneity. Transmission electron microscopy with immunogold labeling also revealed the presence of rgp120 on the surface of the DRVs. In vitro bioassays demonstrated slow leakage of biologically active cytokines from DRVs soaked in tissue culture medium containing serum. Mice injected subcutaneously three times at 14-day intervals with DRVs containing 15 micrograms of rgp120 plus interleukin 6 (IL-6) or interferon gamma (IFN-gamma) produced significantly greater DTH responses than mice injected with DRVs containing rgp120 alone. Soluble rgp120 plus soluble IFN-gamma produced DTH in some experiments, but of lower magnitude than the comparable DRVs. Interleukin 6, but not IFN-gamma, increased the antibody titer to rgp120 when included in the DRVs. The mice did not develop antibodies to IFN-gamma or IL-6. Induction of DTH by vaccines may increase protection from viral pathogens such as HIV. Cytokine-containing liposomes may be an effective adjuvant for the induction of a DTH response to envelope-antigen subunit vaccines.

Antitumor effects of liposomal IL1 alpha and TNF alpha against the pulmonary metastases of the B16F10 murine melanoma in syngeneic mice.

Interleukin 1 alpha (IL1 alpha) and tumor necrosis factor alpha (TNF alpha) have been successfully incorporated into specific phosphatidylcholine (PC) and phosphatidylserine (PS) multilamellar vesicle (MLV) liposomes by modifying the concentration of calcium ion and pH of the encapsulation buffer. Under these conditions, some of the cytokines may attach to the exterior surface of the MLV and therefore be readily accessible to target cells for receptor binding and signal transduction. These cytokine-associated liposomes are stable for up to 2 weeks in serum-free buffer, and leakage of cytokines into medium containing 10% fetal bovine serum was about 50% at the end of a 3-day incubation period at 37 degrees C. The biological activities mediated by liposomal IL1 alpha and TNF alpha were specific: the stimulation of thymidine uptake in T-helper D10 lymphocytes and the cytolysis of TNF alpha-sensitive L929 target cells could be blocked by specific neutralizing antibodies in a dose-dependent fashion. When administered intravenously into C57BL/6 mice bearing the syngeneic B16F10 murine melanoma cells, dual entrapment of liposomal IL1 alpha and TNF alpha significantly reduced the number of metastatic tumor nodules in the lungs and prolonged the life span of the animals. Thus, liposomal IL1 alpha and TNF alpha displayed significant in vivo antitumor activity against the IL1 alpha- and TNF alpha-resistant B16F10 metastatic murine melanoma.

Cloning and genetic characterization of the human kinesin light-chain (KLC) gene.

We report the isolation, sequence, and identification of a cDNA encoding the human kinesin light-chain (KLC) protein. The cDNA molecule consisted of 276 nucleotides of 5' untranslated region, the complete coding sequence of 1,710 nucleotides, and 322 nucleotides of 3' untranslated region. It encoded a polypeptide of 569 amino acids and a deduced molecular mass of 64,789 daltons. The predicted secondary internal structure of the KLC molecule consisted of about 27 contiguous repeats, each of approximately 21 amino acid residues, and could be divided into three domains. The amino-terminal domain consisted of heptad repeats typical of the rod domain of several cytoskeletal proteins. The central and carboxy-terminal domains consist of 21-mer repeats. KLC mRNA was expressed in most tissues analyzed. The gene, which was expressed in bacteria and Chinese hamster ovary cells, was provisionally assigned to the long arm of human chromosome 14.

Inhibition of interleukin-1-alpha-induced nitric oxide synthase in vascular smooth muscle and full reversal of interleukin-1-alpha-induced hypotension by N omega-amino-L-arginine.

BACKGROUND: Interleukin-1-alpha (IL-1) is a cytokine with potentially therapeutic immunoproliferative and tumoricidal activities. Preliminary clinical studies suggest that use of IL-1 may be restricted by dose-limiting hypotension. PURPOSE: The purpose of this study was to investigate the role of nitric oxide (NO.) as a possible mediator of this hypotension. METHODS: Cytokine-treated rat aortic smooth muscle cells were assayed for nitrite production, a stable breakdown product of nitric oxide. Nitric oxide synthase from smooth muscle cells was partially characterized in cytosol preparations using a novel Fe(2+)-myoglobin method to test for nitric oxide production. To determine the role of NO. on the immunorestorative and antineoplastic activity of IL-1, N omega-amino-L-arginine (NAA) or N omega-monomethyl-L-arginine (NMA), inhibitors of nitric oxide synthase, were added to either cultures of IL-1-dependent T cells or A375 melanoma cells exposed to IL-1. To investigate the effects of NAA in vivo, pentobarbital anesthetized dogs, which were made hypotensive by administration of IL-1, received a single intravenous bolus dose of NAA. The effects of NAA were then reversed by the administration of L-arginine. RESULTS: Our results show that cultured IL-1-activated rat aortic smooth muscle cells synthesize nitric oxide, a potent vasodilator. Induction of nitric oxide synthase is augmented by interferon-gamma and blocked by IL-1 receptor antagonist and by inhibitors of RNA or protein synthesis. Nitric oxide synthesis by IL-1-activated smooth muscle cells is inhibited by NAA, NMA, and N omega-nitro-L-arginine (NNA) with ED50 (i.e., effective dose for 50% inhibition) values of 20, 60, and 1000 microM, respectively; this rank order of inhibition is characteristic of an agonist-unregulated, inducible isoform of nitric oxide synthase. In smooth muscle cells, inhibition of NO. synthesis by NAA is reversed by excess L-arginine. Consistent with the induction of unregulated NO. synthesis in vascular smooth muscle in vivo, administration of IL-1 (50 micrograms/kg) to dogs caused a 33.5% decrease in systemic vascular resistance and a 28% decrease in blood pressure within 3 hours. Subsequent administration of NAA (20 mg/kg) rapidly and completely reversed the hypotension and increased systemic vascular resistance; these effects of NAA were reversed by L-arginine. Neither the immunoproliferative nor the tumoricidal activity of IL-1 was diminished by NAA. CONCLUSIONS: Our results indicate that (a) vascular smooth muscle is a likely source as well as a target of IL-1-induced NO. synthesis, causing vasodilatation and hypotension, (b) nitric oxide synthase inhibitors can fully reverse this hypotension, and (c) the therapeutically useful properties of IL-1 are not diminished by nitric oxide synthase inhibitors. IMPLICATIONS: Administration of inhibitors of nitric oxide synthase can reverse the pathological cardiovascular effects of IL-1 at concentrations that do not interfere with the potentially useful immunoproliferative or tumoricidal effects of this cytokine. In the context of the current clinical trials of IL-1, this finding would represent a very significant advantage.

Induction of IL-1: independent production of IL-1 alpha and IL-1 beta.

Lipopolysaccharide (LPS) either in its soluble form or associated with multilamellar phospholipid vesicles (liposomes) was investigated for its ability to induce human monocyte interleukin (IL)-1 alpha and IL-1 beta. When human monocytes were activated in vitro by LPS either in its soluble form or presented at the surface of lyophilized multilamellar vesicles (Lyo-MLV-LPS), both IL-1 alpha and IL-1 beta were detected intracellularly and extracellularly, using specific antisera. In correlation with these findings, the mRNAs for IL-1 alpha and IL-1 beta were both found by Northern blot analysis. However, when human monocytes were stimulated by LPS incorporated into multilamellar vesicles which had not been previously lyophilized, a different pattern of IL-1 protein and message was observed. IL-1 alpha activity was detected only intracellularly and not in the supernatant, while IL-1 beta was not produced at all. Northern blotting revealed only mRNA for IL-1 alpha as soon as 0.5 h after stimulation and none for IL-1 beta. These data indicate independent induction of IL-1 alpha and IL-1 beta. Moreover, it appears that the regulation occurs at the transcriptional level, since with MLV-LPS only the mRNA for IL-1 alpha was induced. The lack of IL-1 beta could be due to either a blockage at the DNA level, an undetectable level of IL-1 beta mRNA, or a very short halflife for IL-1 beta mRNA. These findings indicate that although IL-1 alpha and IL-1 beta may have identical biological properties and share the same receptor, their induction and secretion are regulated by independent pathways.(ABSTRACT TRUNCATED AT 250 WORDS)

Secretion of IL-1: role of protein kinase C.

In an attempt to define the mechanism by which endotoxin induces its biologic activity, LPS was incorporated into phospholipid vesicles (liposomes) and compared with free LPS for ability to stimulate human monocytes. Activation of human monocytes by free LPS caused the translocation of protein kinase C (PKC) from the cytosol to the plasma membranes, the production of both IL-1, alpha and beta, and IL-1 secretion. Activation by LPS presented in multilamellar vesicles (MLV)-LPS caused IL-1 production but not IL-1 secretion. Moreover, MLV-LPS did not induce PKC translocation. MLV themselves did not inhibit monocyte stimulation by LPS, since LPS presented at the surface of lyophilized liposomes behaved like free LPS in cell activation. In contrast, MLV-LPS primed monocytes for subsequent LPS stimulation. When monocytes were activated by LPS in the presence of PKC inhibitors, no plasma membrane-associated PKC or IL-1 secretion was detected, whereas IL-1 production was observed. PKC inhibitors did not affect IL-1 alpha and IL-1 beta production, showing that PKC is not involved in the production of either IL-1. It can be concluded that IL-1 production and secretion are induced independently, and that IL-1 secretion involves PKC.

Acylation of cell-associated IL-1 by palmitic acid.

To determine whether membrane-associated IL-1 is palmitylated, we labeled LPS-activated human monocytes with [3H]palmitic acid. The plasma membranes were isolated, and the membrane proteins extracted and analyzed simultaneously by SDS-PAGE-autoradiography and Western blot analysis from the same gel. When the monocytes were labeled with [3H]palmitate, 23- and 31-kDa bands were visualized, for membrane-associated IL-1 and its precursor, respectively. The 31- and 23-kDa bands were excised from several gels and rehydrated and analyzed again by SDS-PAGE, autoradiography, and Western blot analysis. The 23- and 31-kDa bands appeared again by both methods. To further investigate membrane-associated IL-1 acylation, human monocytes were labeled with [3H]palmitate, the plasma membranes isolated, and the membrane proteins extracted by CHAPS detergent. Immunoprecipitation of isolated membrane proteins using anti-IL-1 antibodies revealed two bands of 23 and 31 kDa after autoradiography. The studies demonstrate that both membrane-associated IL-1 and the IL-1 precursor are acylated with palmitic acid.

Antigen presentation by liposomes bearing class II MHC and membrane IL-1.

Liposomes containing membrane IL-1, Iak, and the antigen conalbumin were evaluated as "synthetic antigen presenting cells." The role of these three molecules in macrophage-T cell interaction was studied by testing their ability to induce the proliferation of a T-cell clone specific to conalbumin (the D10 cell line) or immune spleen cells sensitized three times in vivo with conalbumin. In the latter case, splenic macrophages were eliminated by adherence and a lysomotropic agent. The antigen conalbumin was presented on the surface of the liposomes as native undigested protein. When the liposomes presented native conalbumin, Iak, and membrane IL-1, significant proliferation occurred, but if the liposomes lacked membrane IL-1, the proliferation of the T-cell clone and the spleen cells reached only about 60 percent of the previous signal. Native conalbumin and class II antigen alone were required for T-cell activation, while membrane IL-1 only amplified the response. When the liposomes were made with only Iak and membrane IL-1, lacking conalbumin, there was no proliferation of antigen-specific target cells. These results indicated that in this synthetic system, membrane IL-1 increases the magnitude of the response but is not essential for the proliferative response of antigen-specific T cells.

Synthetic macrophages: liposomes bearing antigen, class II MHC and membrane-IL-1.

Liposomes containing membrane-IL-1, Iak, and the antigen conalbumin were evaluated as "synthetic macrophages." The role of these three molecules in macrophage-T cell interaction was studied by testing the ability of such synthetic macrophages to induce the proliferation of a T cell clone specific to conalbumin (the D10 cell line) or immune spleen cells sensitized three times in vivo with conalbumin. In the latter case, splenic macrophages were eliminated by adherence and a lysomotropic agent. The antigen conalbumin was presented on the surface of the liposomes in two forms: as native undigested protein or as a complex of Iak and naturally processed peptides isolated from peritoneal macrophages incubated with conalbumin. When the liposomes presented the Ia antigen associated with conalbumin-peptides and membrane-IL-1, the proliferation of both the D10 and the immune spleen cells was high and maximal. The proliferation response of both cell types was completely dependent on the presence of membrane-IL-1, since no proliferation occurred when liposomes were prepared with only conalbumin-peptides bound to Iak. Therefore, it could be concluded that processed antigen associated with class II MHC antigen and membrane-IL-1 were required for T cell activation. When the liposomes presented native conalbumin, Iak, and membrane-IL-1, significant proliferation occurred, but if the liposomes lacked membrane-IL-1, the proliferation of the T cell clone and the spleen cells decreased to only 40-50% of the previous signal. In this case native conalbumin and class II antigen alone were required for T cell activation, while membrane-IL-1 alone amplified the response. When the liposomes were made with only Iak and membrane-IL-1, lacking either form of conalbumin, there was no proliferation of antigen-specific target cells. These results indicated that in this synthetic system, membrane-IL-1 is essential for the proliferative response of antigen-specific T cells when conalbumin is presented as processed peptides in association with Iak.

Heterogeneity of interleukin 1 production in cultured Reed-Sternberg cell lines HDLM-1, HDLM-1d, and KM-H2.

Interleukin 1 (IL-1) is known for its role in modulating the immune response and is required for initiation of lymphocyte proliferation by means of increased IL-2 production by lymphocytes. Previously, the expression of IL-1 in H-RS cells in tissue sections was shown by using immunoperoxidase staining. For further confirmation, the production of IL-1 in cultured cells of the H-RS cell lines HDLM-1, HDLM-1d, and KM-H2 was examined by using a murine D10.G4.1 T cell proliferation bioassay and Northern blot hybridization with specific IL-1 cDNA probes. It was confirmed that two types of H-RS cells, HDLM-1 and KM-H2, can secrete IL-1, especially after treatment with phorbol ester. The amounts of IL-1 in H-RS cell culture medium ranged from approximately 0.5 to 2.5 ng/ml. The major IL-1 secreted by HDLM-1 cells was IL-1 alpha, and by KM-H2 cells was IL-1 beta. HDLM-1d cells did not produce IL-1. This finding indicates the heterogeneity of IL-1 production in H-RS cells. Such heterogeneity may apply to H-RS cells in vivo, based on the variable IL-1 staining of these cells in lymphoid tissues.