Class I MHC molecules and doxorubicin resistant P388 murine leukemic cells

The major histocompatibility complex (MHC) encodes cell surface and secreted products involved in immune regulation and function. We have measured Class I MHC expression on doxorubicin (DOX) sensitive (P388/S) and resistant (P388/R84 and R84A) murine tumor cells using a monoclonal antibody to H-2d molecules. The present report shows a correlation between increased Class I MHC (H-2d) expression and drug resistance in P388 cells. Exposure of P388 cells to H-2d antibody diminished H-2d expression, whereas, treatment with murine recombinant gamma-interferon increased H-2d expression. Neither treatment significantly altered cellular DOX resistance or chemosensitivity. Thus, H-2d molecules can be used to identify DOX resistant P388 tumor cells but are probably not involved functionally in drug resistance.

Graft-versus-host-related immunosuppression is induced in mixed chimeras by alloresponses against either host or donor lymphohematopoietic cells

Graft-vs.-host (GVH)-related immunosuppression has previously been demonstrated in F1 rodent recipients of parental lymphoid cells, and has been thought to result from an immunologic attack of the donor against the host. Since all cells of such F1 recipients could potentially bear target class I MHC alloantigens, it has not previously been possible to determine precisely the target tissues responsible for development of GVH-related effects. In the present studies we have used mixed allogeneic chimeras as recipients of host or donor-strain lymphocyte inocula, and have made the surprising observation that "GVH-induced" immune unresponsiveness does not require GVH reactivity, per se, but develops in the presence of a one-way alloresponse against lymphohematopoietic cells in either the GVH or the host-versus-graft direction.

Positive and negative selection of an antigen receptor on T cells in transgenic mice

The T-cell repertoire found in the periphery is thought to be shaped by two developmental events in the thymus that involve the antigen receptors of T lymphocytes. First, interactions between T cells and major histocompatibility complex (MHC) molecules select a T-cell repertoire skewed towards recognition of antigens in the context of self-MHC molecules. In addition, T cells that react strongly to self-MHC molecules are eliminated by a process called self-tolerance. We have recently described transgenic mice expressing the alpha beta T-cell receptor from the cytotoxic T lymphocyte 2C (ref. 11). The clone 2C was derived from a BALB.B (H-2b) anti-BALB/c (H-2d) mixed lymphocyte culture and is specific for the Ld class I MHC antigen. In transgenic H-2b mice, a large fraction of T cells in the periphery expressed the 2C T-cell receptor. These T cells were predominantly CD4-CD8+ and were able to specifically lyse target cells bearing Ld. We now report that in the periphery of transgenic mice expressing Ld, functional T cells bearing the 2C T-cell receptor were deleted. This elimination of autoreactive T cells appears to take place at or before the CD4+CD8+ stage in thymocyte development. In addition, we report that in H-2s mice, a non-autoreactive target haplotype, large numbers of CD8+ T cells bearing the 2C T-cell receptor were not found, providing strong evidence for the positive selection of the 2C T-cell receptor specificity by H-2b molecules.

A region of the influenza A/NT/60/68 PB2 protein containing an antigenic determinant recognized by murine H-2Dd restricted cytotoxic T lymphocytes

We have used a recombinant vaccinia virus to investigate the recognition of the PB2 protein of influenza A/NT/60/68 (H3N2) by murine polyclonal CTL populations. PB2 is recognized as a major cross-reactive target antigen. Recognition of PB2 is under strict genetic control, since BALB/c (H-2d) but not CBA (H-2k) mice are responders. We also demonstrate, by use of cell lines transfected with individual genes encoding class I molecules of the H-2d haplotype, that recognition of PB2 occurs in conjunction with the H-2Dd but not the H-2Kd or H-2Ld molecules. In contrast, recognition of the nucleoprotein of A/PR/8/34 by BALB/c-derived polyclonal CTL is restricted via the H-2Kd molecule. By using three recombinant vaccinia viruses expressing deleted forms of the PB2 protein we show that at least one epitope of the PB2 protein resides within the amino-terminal 256 amino acids. This approach offers an effective method to map the regions of large proteins containing epitopes recognized by CTL.

Positive selection of antigen-specific T cells in thymus by restricting MHC molecules

Thymus-derived lymphocytes (T cells) recognize antigen in the context of class I or class II molecules encoded by the major histocompatibility complex (MHC) by virtue of the heterodimeric alpha beta T-cell receptor (TCR). CD4 and CD8 molecules expressed on the surface of T cells bind to nonpolymorphic portions of class II and class I MHC molecules and assist the TCR in binding and possibly in signalling. The analysis of T-cell development in TCR transgenic mice has shown that the CD4/CD8 phenotype of T cells is determined by the interaction of the alpha beta TCR expressed on immature CD4+8+ thymocytes with polymorphic domains of thymic MHC molecules in the absence of nominal antigen. Here we provide direct evidence that positive selection of antigen-specific, class I MHC-restricted CD4-8+ T cells in the thymus requires the specific interaction of the alpha beta TCR with the restricting class I MHC molecule.

Recognition by cytotoxic T lymphocytes of Qa-2 antigens. Sensitivity of Qa-2 molecules to phosphatidylinositol-specific phospholipase C

Con A splenic lymphoblasts were incubated with phosphatidyl-inositol specific phospholipase C (PIPLC) derived from Bacillus thuringiensis and subsequently analyzed for Qa-2 Ag with the Qa-2 reactive mAb Qa-m2. This treatment completely removed Qa-2 detectable Ag on lymphoblasts from H-2d animals, indicating that these molecules are likely anchored to the cell membrane through phosphatidyl inositol (PI). Although exposure of lymphoblasts from H-2b mice to PIPLC greatly reduced Qa-2 expression, a subpopulation of cells retained a limited quantity of the Ag. Bulk cultured anti-Qa-2 CTL generated against the Qa-2 region from H-2b haplotype mice lysed Qa-2+ targets from B6.K2 (H-2b) and BALB/cJ (H-2d) animals. Pretreatment of these lymphoblast targets with PIPLC completely abolished lysis of the BALB/cJ target cells, whereas lysis of B6 targets was reduced only slightly. Anti-Qa-2 CTL clones tested against PIPLC-treated B6 target cells revealed two patterns of reactivity. One group of clones was unaffected in its ability to lyse PIPLC-pretreated targets and cross-reacted on Q6d/Ld molecules expressed on transfected L cells. A second group was unable to lyse PIPLC-pretreated lymphoblasts and cross-reacted on Q7d/Ld targets. These data suggest that H-2b-derived lymphoblasts express two different types of Qa-2 molecules with respect to PIPLC sensitivity; one type is sensitive to PIPLC and cross-reactive with Q7d, the other type is resistant to PIPLC and cross-reactive with Q6d. In contrast, H-2d lymphoblasts express only the PIPLC-sensitive type of molecules. It was also noted that bulk cultured anti-Qa-2 CTL more readily lysed H-2b target cells expressing a smaller quantity of PIPLC-resistant Ag than H-2d targets expressing a larger amount of PIPLC-sensitive Ag. Further, anti-Qa-2 CTL clones readily lysed PIPLC-treated target cells expressing very low levels of serologically detectable Qa-2. This suggests that recognition of class I molecules anchored to the membrane via a PIPLC-resistant linkage may more readily activate CTL for expression of lytic activity than molecules anchored through PI.

Stimulation of antigen-specific murine T cell clones in vitro with antigen-pulsed adherent cells fixed to a carrier

Antigen pulsed antigen presenting cells (APCs) were fixed to a carrier (culture flask or microtiter plate) to stimulate antigen-specific T cell clones in vitro. The resulting stimulation was comparable with that in which free antigen together with irradiated APCs were used and the antigen concentration was less critical in the case of toxic antigens. It was shown that the carriers coated with pulsed APCs could be stored for 12 weeks without loss of stimulatory capacities, provided that the APCs were fixed. In addition it was demonstrated that coated carriers could be used thrice to stimulate T cells in vitro without affecting the stimulating properties. The observed T cell proliferation was both antigen specific and MHC restricted. The main advantages of this novel method were the standardization of antigen stimulation of T cells achieved in vitro and the availability of a 100% pure T cell population immediately after stimulation, both features contributing to more reproducible experiments with T cell clones or lines in vivo and in vitro.

Automated fluorometric assay for T cell cytotoxicity

A fluorometric assay avoiding the use of radioactivity has been developed for detecting cytotoxic T lymphocytes (Tc cells). The method involves labelling targets with Hoechst dye no. 33342 (H33342) which becomes brightly fluorescent on binding to DNA. Lysis of target cells by Tc cells is quantified by measuring the release of fluorescent H33342 into the supernatant of culture wells. The fluorescence is measured using an automated Microfluor reader which allows results to be obtained rapidly. The assay has been used to detect alloreactive Tc cells and H-2 restricted Tc cells against influenza virus in a short-term 6 h assay using P815 and L929 as targets with comparable results to those obtained with 51Cr labelling. In contrast, lymphocyte blasts were found to be less sensitive in 6 h fluorometric assays when compared with the 51Cr assay. In long-term overnight assays (possible because of the low spontaneous release of H33342 from targets) lymphocyte blasts gave high specific lysis and some anti-self reactivity. The cause of the anti-self reactivity may reflect fundamental differences between the H33342 and 51Cr release assays.

Conversion of a PI-anchored protein to an integral membrane protein by a single amino acid mutation

Qa-2, a cell-surface glycoprotein anchored by phosphatidylinositol (PI), is structurally related to the class I transplantation antigens H-2 K, D, and L, which are integral membrane glycoproteins. The predicted transmembrane segment of Qa-2 differs from those of H-2 K, D, and L by the presence of an aspartate in place of a valine at position 295. A single base change that replaced this aspartate with valine resulted in cell-surface Qa-2 molecules that were insensitive to hydrolysis by a PI-specific phospholipase C and more resistant to papain cleavage, properties shared by H-2D. Cells expressing Asp----Val mutant Qa-2 proteins were still able to attach a PI anchor to endogenous proteins such as Thy-1 and J11D. It therefore appears that this single amino acid change converts Qa-2 from a PI-linked form into an integral membrane protein.

Augmented in vitro presentation of Mls determinants after anti-immunoglobulin-induced B cell activation: ontogeny and role of purified B cells

Murine splenocytes which contained B cells activated by in vivo exposure to affinity-purified goat anti-mouse IgD (GaMD) antibody were utilized to present major histocompatibility complex (MHC) and non-MHC minor lymphocyte-stimulating (Mlsa) determinants in a primary mixed lymphocyte reaction (MLR). As the time in hours after in vivo exposure to GaMD increased, splenocytes from adult mice showed a co-ordinate increase in cell size, expression of public and private MHC class II antigenic determinants and MHC and Mlsa antigen-presenting capacity. This augmented alloantigen-presenting capacity was demonstrable with either irradiated or mitomycin C-treated adult splenocytes. In contrast, GaMD-treated neonatal splenocytes from 10-day-old mice demonstrated no significantly increased class II expression or enhanced MHC stimulatory capacity, but nevertheless triggered augmented responder cell proliferation across an Mlsa barrier. Thus, increased class II expression or presenting capacity may not be required for an augmentation in splenocyte Mls-stimulating ability to occur. In vitro exposure of T cell-depleted splenocytes or highly purified small resting B cells to GaMD or lipopolysaccharide (LPS) induced a substantially increased ability in those populations to present MHC and Mlsa antigens in a primary MLR. Hence in vivo or in vitro activation of B lymphocytes in a stimulator cell population may yield more effective presentation of MHC and non-MHC determinants.

Synergy between stimulator cells in the induction of the anti-Mlsa response

We have identified two types of clones responsive to Mls determinants. One type responded vigorously to purified B cells from mice bearing Mlsa-stimulatory determinants. The other type, including clone Ly1-N5, responded vigorously to unfractionated spleen cells, but failed to respond to B cells alone or to spleen-adherent cells (SAC) alone from the Mlsa-bearing mice. Synergy between two stimulator cell types, B cells and SAC, was required to induce the Mls response of clone Ly1-N5. The failure of clone Ly1-N5 to respond to Mlsa-bearing B cells was reversed by the addition of SAC taken from mice bearing the Mlsa allele or the non-stimulatory Mlsb allele. B cells were required to provide the Mlsa determinant. The Mls response of clone Ly1-N5 is restricted by class II determinants shared by the H-2b, H-2d and H-2k haplotypes, but not the H-2q haplotype. The optimal response of the clone was obtained by using B cells bearing both Mlsa and the permissive H-2 alloantigen. However, complementation was also observed between B cells bearing Mlsa and the non-permissive Iaq and SAC bearing the nonstimulatory Mlsb, but a permissive Ia epitope, resulting in activation of the clone. Clone Ly1-N5 responds to Mlsa-bearing B cells only in the presence of SAC.(ABSTRACT TRUNCATED AT 250 WORDS)

Site-directed mutagenesis of class I HLA genes. Role of glycosylation in surface expression and functional recognition

We have investigated the role of the carbohydrate moiety on the HLA-B7 molecule in mAb and CTL recognition using oligonucleotide-directed mutagenesis and gene transfer techniques. A conservative substitution of asparagine to glutamine at amino acid 86 in HLA-B7 was created to abolish the unique glycosylation site present on all HLA molecules. A second mutant B7 molecule was made by substituting asparagine-aspartic acid-threonine for the resident lysine-aspartic acid/lysine tripeptide at amino acids 176-178, thus creating an N-linked glycan at amino acid 176, which is additionally present on all known murine H-2 class I antigens. Upon gene transfer into mouse and human cell recipients, the HLA-B7M176+ mutant and normal HLA-B7 expressed identical levels of surface protein. However, the binding of two mAbs (MB40.2 and MB40.3) thought to recognize different epitopes of the HLA-B7 molecule was completely eliminated. In contrast, the HLA-B7M86- mutant displayed no surface expression (mouse L cells) or minimal surface expression (human RD cells or mouse L cells coexpressing human beta 2 microglobulin [beta 2m]) after indirect immunofluorescence (IIF) and flow cytometric analysis with a panel of 12 HLA-B7 mAb reactive with monomorphic and polymorphic determinants. Immunoprecipitation analysis demonstrated that intracellular denatured mutant protein was present. Tunicamycin treatment did not rescue the expression of HLA-B7M86- antigens to the cell surface; while interferon did induce higher levels of surface expression. Tunicamycin treatment also did not allow binding of the mAbs MB40.2 or MB40.3 to HLA-B7M176+ mutant antigens, suggesting that the carbohydrate moiety itself was not directly involved in the recognition or conformation of these mAb epitopes. Further mutation of the B7M86- molecule to create a glycan moiety at amino acid position 176 (B7M86-/176+) did not rescue normal levels of surface expression. Finally, neither mutation was seen to affect recognition by a panel of 12 allospecific CTL clones. The low expression of HLA-B7M86- on the surface of human cell transfectants was sufficient to achieve lysis, albeit at a reduced efficiency, and lysis could be increased by interferon induction of higher levels of expression. Thus, the carbohydrate moiety on HLA antigens plays a minimal or nonexistent role in recognition by available mAb and allospecific CTL clones.

Complete Freund's adjuvant has a differential amplification action on the induction of diabetes by streptozotocin in various murine strains: CFA amplifies STZ in murine diabetes

The effect of complete Freunds Adjuvant (CFA) has been investigated on the multi-low-dose streptozotocin (STZ) model of diabetes in mice of the H-2b (C57Bl/6) and of the H-2k (A/J, CBA) genotypes. Physiological (glycemia and body weight) and morphological (insulitis) parameters were monitored. STZ was used at standard and sub-diabetogenic dose levels (45 and 22.5 mg/kg STZ, for five consecutive days respectively) and CFA was given as a single dose (0.1 ml) on the first dosage day. In H-2k mice, CFA was synergistic with STZ at 45 mg/kg but did not cause the 22.5 mg/kg dose to raise glycemia to diabetic levels. By comparison, CFA was not synergistic with STZ at 45 mg/kg in H-2b mice, but did convert the subdiabetogenic dose to a diabetogenic action in these animals. Histologically, it was noted that insulitis was a more prominent and persistent feature of the H-2k mice. It occurred at the subdiabetogenic dose level of STZ in H-2k mice, in the absence of increased glycemia, suggesting that these two phenomena are not related. CFA, either alone, or with STZ, caused severe persistent perilobular inflammation of the exocrine pancreas. It did not increase the incidence or severity of insulitis. A possible mechanism whereby CFA is synergistic with STZ at different doses in H-2b and H-2k mice is suggested.

Utilization of antigen specific cytotoxic T-cells as a sensitive approach to investigate the fate of placentally injected allogeneic lymphocytes

In this report we present a model for the introduction of immunocompetent populations during murine gestation and the subsequent detection of allogeneic cells in the offspring. A highly sensitive in vitro assay, the primed lymphocyte cytotoxicity assay, which can detect extremely low numbers of allogeneic cells residing within host tissue is described. Primed cytotoxic T cells specific for class I antigens were found to be restimulated by as few as 10-50 allogeneic spleen cells from within 10,000 syngeneic neonatal spleen or liver cells. Various tissues derived from neonatal mice which had been placentally injected 1 or 10 days previously were found to contain markedly different percentages of "chimeric" cells in the neonatal organs examined. Notably, while spleen and lung contained more allogeneic cells early following injection, 10 days later the liver contained the highest percentage and the thymus and spleen a significantly lower percentage of allogeneic cells. These findings are discussed with respect to the possible enhancement or depression of the offspring's immune responsiveness following interaction with alloantigen bearing lymphoid cells.

Variation of hepatic fibrosis and granuloma size among mouse strains infected with Schistosoma mansoni

To investigate the relation between the size of circumoval granulomas and hepatic fibrosis, a variety of mouse strains infected with Schistosoma mansoni were examined and the number of eggs in the tissues, the fibrotic responses to the eggs, and the volume of the granulomas were determined. Marked differences in granuloma volume and in hepatic fibrosis were found between mouse strains, and those strains with the largest granulomas also showed the most hepatic fibrosis. On the other hand no significant correlation between granuloma size and hepatic fibrosis was found in the progeny of the F2 generation and backcrosses between F1 mice and the parental strains when crosses were made between Nmri mice (high granuloma volume and high fibrosis) and C57BL/6 mice (low granuloma volume and low fibrosis). Hepatic fibrosis per egg decreased with increasing infection intensity while granuloma volume was unaffected, indicating that fibrosis and granuloma size are at least in part modulated by different factors. The number of eggs found in the tissues per worm pair and the proportion of eggs in the liver also decreased as infection intensity increased. Some influence of the major histocompatibility complex on both granuloma size and fibrosis was found. Congenic mice on the C57BL/10 and C3H/HeSn backgrounds showed larger granulomas in H-2b than in H-2k mice, but no such correlation was found in comparing C57BL/6 mice with B6.H-2k mice. Less hepatic fibrosis was found in B10.M (H-2f), B10.SM (H-2v), and B10.RIII (H-2r) animals than in C57BL/10 mice. The regulation of granuloma size and of hepatic fibrosis is clearly complex and involves genes both outside of and within the major histocompatibility complex.

Genetics of natural resistance to herpes simplex virus type 1 latent infection of the peripheral nervous system in mice

The genetics of natural resistance to the development of latent infection in the trigeminal ganglia of mice inoculated in the lip with herpes simplex virus type 1 (HSV-1) was examined. Based on coefficients of a logistic regression relating latency to strain and HSV-1 concentration, inbred strains of mice formed a continuum of resistance ranging from most resistant (C57BL/6J) to most susceptible (PL/J). When these results were analysed along with latency data derived from studies employing a non-fatal concentration of HSV-1, three subpopulations were identified among these strains: resistant (C57BL/10J, BALB/cByJ, C57BL/6J), moderately resistant (DBA/2J, SWR/J, A/J, AKR/J, DBA/1J) and susceptible (PL/J, LP/J, CBA/J). Results from F1 hybrids between resistant and moderately resistant strains (B6D2F1/J, B6AF1/J) and between resistant and susceptible strains [(C57BL/6J X CBA/J)F1, (C57BL/6J X LP/J)F1)] indicated that resistance is dominant. Data from both inbred and congenic strains failed to show an association between H-2 and resistance to the development of a latent infection. Studies of mortality also indicated that a continuum was present, with C57BL/10J, C57BL/6J and DBA/1J being most resistant and PL/J mice most susceptible. When inbred strains were categorized on the basis of resistance to the development of latent infection and mortality, five groups could be identified. Group A are strains resistant to both mortality and latency (C57BL/6J, C57BL/10J, DBA/1J) while group B consists of one strain (BALB/cByJ) intermediate in resistance to mortality but resistant to latency. Group C are strains intermediate in resistance to mortality and susceptible to latency (LP/J, CBA/J) while Group D are strains susceptible to mortality and intermediate in susceptibility to latency (AKR/J, SWR/J, DBA/2J). Group E consists of one strain (PL/J) susceptible to both mortality and latency. These results indicate that host factors play an important role in the establishment of latent infection in vivo.

Properties of purified T cell subsets. II. In vivo responses to class I vs. class II H-2 differences

Highly purified populations of C57BL/6 (B6) L3T4+ and Lyt-2+ T cell subsets were compared for their capacity to exert alloreactivity to class I vs. class II H-2 differences in vivo. B6 Lyt-2+ cells responded strongly to the class I different mutant, bm1, as manifested by DNA synthesis in the spleen of irradiated mice followed by entry of blast cells into thoracic duct lymph, induction of splenomegaly in newborn mice, production of lethal GVHD in irradiated mice, and skin allograft rejection. By all of these parameters, B6 Lyt-2+ cells showed almost total unresponsiveness to the class II-different mutant, bm12. Reciprocal results were observed with B6 L3T4+ cells, these cells responding strongly against bm12 but not against bm1. In the case of purified T cell subsets from other strains, CBA/Ca and B10.BR L3T4+ cells both responded well to a full H-2 difference. Responses by Lyt-2+ cells from these strains were weaker, especially for CBA/Ca cells. The implications of these findings are discussed.

Sheep lymphocyte antigens (OLA). II. Major histocompatibility complex class II molecules

A panel of monoclonal antibodies have been produced which recognize monomorphic determinants of sheep MHC Class II antigens, including an allogenically derived murine monoclonal antibody specific for the I-E gene product. Immunoprecipitation and SDS-PAGE analyses indicates that these monoclonal antibodies recognize a non-covalently associated glycoprotein complex of molecular weight 30-32 kDa (alpha chain) and 24-26 kDa (beta chain). One and two colour immunofluorescence was used to measure the distribution of these 'Ia-like' antigens on mononuclear cells from various lymphoid organs. They were found almost exclusively on lymphocytes expressing surface immunoglobulin (B lymphocytes) and on a small population of surface immunoglobulin negative cells. Most thymocytes were negative for Class II molecules while thymic epithelial cells were positive. The tissue distribution of Class II molecules was found to be similar to that described in man. Individual monoclonal antibodies displayed no variations in reactivity with the different tissues studied.

Molecular association between major histocompatibility complex class I antigens and insulin receptors in mouse liver membranes

Molecular association between major histocompatibility complex (MHC) antigens and cellular proteins are thought to be involved in various immunological and nonimmunological functions of MHC antigens, including hormone signaling. The existence of physical interactions between insulin receptors and MHC class I antigens was investigated in liver plasma membranes from congenic H-2k mice. Insulin receptors were specifically labeled with a 125I-labeled photoreactive insulin analogue, and cellular proteins were solubilized and incubated with various monoclonal antibodies. Immunoprecipitates were analyzed by polyacrylamide gel electrophoresis followed by autoradiography. Antibodies reacting with distinct epitopes on H-2k class I antigens were all able to precipitate up to 25% of the labeled insulin receptors in H-2k mouse liver membranes, whereas no insulin receptors were precipitated in H-2b mouse liver membranes. Sequential immunoprecipitations showed that insulin receptors and H-2 antigens were coprecipitated and that no cross-reactivity occurred. The specificity of the interaction between insulin receptors and H-2 antigens was demonstrated after double labeling of membrane proteins by photoreactive insulin and lactoperoxidase-catalyzed iodination. These results thus show that, in mouse liver membranes, insulin receptors are physically associated to class I antigens of the MHC.

New methodology for liposome targeting to specific cells

The specificity of liposomes for different cell types was achieved by conjugation to monoclonal antibodies directed against various cell surface antigens. L929 mouse fibroblast cells were targeted with liposomes conjugated to anti-H2Kk. K562 cells, a human line derived from chronic myelogenous leukemia, were targeted with antiglycophorin. One murine T-lymphoma, AKR/J SL2, was targeted with anti-thy 1.1; another, R1.1, was targeted with anti-H2Kk. The following important parameters were established concerning efficacy of antibody-directed liposomes as a drug delivery system. (1) Targeted liposomes containing methotrexate-gamma-aspartate were 20-40 times more cytotoxic than the free drug or nonspecific liposomes. (2) The use of drugs such as methotrexate-gamma-aspartate, which are unable to enter cells without a carrier, eliminates the nonspecific effects of drug that may leak from the liposomes. (3) Liposomes conjugated to antibody have a higher valency than the soluble antibody and bind to cells with up to 1000-fold higher affinity constant. (4) Liposomes that interact with more than one type of ligand on the cell surface show marked resistance to inhibition of cell association by soluble ligands. (5) The optimal liposome size appears to vary from 0.05 to 0.1 mu, depending on target cell type.

Chemosensory recognition of mouse major histocompatibility types by another species

Mice can recognize one another by individually characteristic body scents that reflect their genetic constitution at the extremely polymorphic major histocompatibility complex (MHC) of genes on chromosome 17. Reproductive behavioral manifestations of this sensory communication system include MHC-related mating preferences and neuroendocrine responses that affect preimplantation pregnancy and arise from the MHC-related scent of alien males. We have shown previously that mice can be trained in a Y maze to distinguish the scents of urine of congeneic mice that differ genetically only at the MHC. By means of an automated olfactometer, we now show that rats also can similarly distinguish the urinary scents of MHC congeneic mice. Thus, the mode of individual recognition that depends on scents determined by MHC genes can operate across species barriers.

In vitro T cell-mediated killing of Pseudomonas aeruginosa. II. The role of macrophages and T cell subsets in T cell killing

T lymphocytes from immune mice can adoptively transfer protection against infection with the extra-cellular Gram-negative bacterium Pseudomonas aeruginosa to nonimmune recipients, and in vitro, immune T cells are able to kill these bacteria. Earlier studies indicated that this killing is mediated by a bactericidal lymphokine. Those studies also showed that macrophages enhance this in vitro T cell killing but do not directly participate in the bacterial killing, nor do macrophages function to present antigen to T cells. The current studies demonstrate that the ability of macrophages to enhance T cell killing can be replaced by macrophage culture supernatants or by purified recombinant interleukin 1 (IL 1). In addition, the macrophage supernatant-induced enhancement can also be blocked by antibody to purified IL 1. These studies also demonstrate that the T cell subset that serves as the final effector cell in the killing process is the Lyt-1-, 2,3+, I-J+ phenotype.

Accessory cells in immune suppression. II. Evidence for presentation of idiotype-specific suppressor factors to B cell targets by I-A+ accessory cells

The functional suppression of two BALB/c myelomas, MOPC315 and MOPC460, by idiotype-specific suppressor T cells is mediated by secreted factors (TsF). Idiotype-specific TsF only functions in the presence of accessory cells (AC) that can be low density splenocytes or cells of BALB/c B lymphoma A20-2J. Such AC are I-A+ but do not have to be histocompatible with the myeloma targets or the source of TsF. A20-2J cells incubated with soluble idiotype and TsF also are capable of suppressing the relevant myeloma target. The effect of TsF-pulsed A20-2J cells is idiotype specific, and these cells do not secrete immunosuppressive mediators. Finally, TsF-pulsed A20-2J cells suppress myeloma targets when the two are cultured on the same side of a cell-impermeable membrane but not when they are separated by the membrane. These results indicate that I-A+ cells are capable of concentrating and/or presenting TsF to suppressible targets, and they demonstrate a novel role for Ia-bearing cells in immune regulation.

Rejection of murine heterotopic corneal transplants

A murine heterotopic corneal transplant model has been developed using s.c. abdominal pouches as recipient sites. Donor-recipient genetic disparities involving H-2 antigens alone or H-2 plus non-H-2 antigens result in high rates of rejection. In addition, donor-recipient disparities involving non-H-2 antigens alone or H-Y antigen also result in significant, although lower, rates of rejection. In comparison, pretreatment of the donor grafts by hyperbaric oxygen, removal of the epithelial layer, or soaking in anti-Ia antibody plus complement results in statistically significant reductions in the rejection rates as compared with fresh, untreated donor tissue. These observations suggest that cells bearing Ia antigens (i.e., Langerhans cells) in the epithelial layer of donor corneas play a major role in host sensitization and subsequent rejection following corneal transplantation in this model. However, other antigens may play a role when Ia antigens are depleted from donor corneas.

Thymus hormones do not induce proliferative ability or cytolytic function in PNA+ cortical thymocytes

A variety of thymus hormone preparations, as well as drugs known to perturb cell differentiation, were tested for their ability to induce nonfunctional cortical thymocytes to become functional precursor cells. Murine cortical thymocytes, defined as the high peanut agglutinin (PNA) binding or as the low H-2K, major [86%] thymocyte subpopulation, were isolated by fluorescence-activated cell sorting. Their function was assessed in a high cloning efficiency, growth factor saturated, concanavalin A-stimulated limit-dilution culture system, determining the number of precursors of extended clones (PTL-p), or determining with a lectin-mediated tumor-lysis readout the number of precursors of cytolytic clones (CTL-p). The hormone preparations tested were crude or partially purified culture supernatants from thymus "epithelial" monolayers (TES), soluble extracts of thymic nonlymphoid tissue (STF), semipure thymus humoral factor (THF), and the pure peptides thymopoietin 32-36 (TP5) and "facteur thymique sérique" (FTS). These preparations were either added directly to the limit dilution cultures, or were first preincubated with the cells, which were then subjected to limit-dilution culture. In no case did the hormone preparations cause any increase in the level of PTL-p or CTL-p in the PNA+ or low H-2K thymocyte population, even though a conversion of only a few percent to functional cells could have been detected. Two possible explanations are considered. One is that the main function of these materials is to control post-thymic peripheral T cells, rather than to induce intrathymic differentiation. Another is that the typical cortical thymocyte is beyond the stage at which thymocytes can be induced by hormones, a view that is strengthened by the failure of either 5-azacytidine or the phorbol ester 12-O-tetradecanoyl phorbol 13-acetate to activate these cells. In this latter explanation the true intrathymic target of hormone action may be an earlier, and very minor, thymus subpopulation.

Cyclophosphamide-induced suppressor cells in mice: suppression of the antibody response in vitro and characterization of the effector cells

It was found earlier that nonspecific suppressor cells obtained from the spleen of mice injected with cyclophosphamide (Cy) at a dose of 200 mg/kg body wt are nonadherent, surface Ig negative, and Thy-1 negative. It is now reported that Cy-induced suppressor (Cy-S) cells suppress the in vitro primary and secondary humoral responses in a dose-dependent manner. Suppressor activity is a property of a low density cell that is found in the spleen from 5 to 11 days after Cy administration. Cy-S cells are negative for a number of T-cell markers and are nonadherent to plastic. They are not agglutinated by peanut agglutinin and do not acquire the Thy-1 antigen after treatment with thymosin, suggesting that they are not T-cell precursors. While NK activity was detected in the Cy-S cell preparations, this activity was removed by treatment with antibodies specific for the Qa-5 antigen and complement without affecting the suppressor activity. Cy-S cells are, therefore, distinct from B cells, T cells, NK cells, and macrophages.

Differences in activity of N2-guanine tRNA methyltransferase II among several inbred strains of mice

The tRNA methyltransferase activities of C57BL/6J, C57L/J, C58/J, AKR/J, and C3H/HeJ inbred mice were studied with the use of various amino acid-specific Escherichia coli tRNA's as substrates. Mice from two strains with high incidence of spontaneous leukemia (AKR/J and C58/J) exhibited levels of liver N2-guanine tRNA methyltransferase II (N2-MeGII) activity that were double those of two strains of mice with low incidence of spontaneous leukemia (C57BL/6J and C57L/J). Activities of liver and kidney N2-MeGII of the high spontaneous hepatoma strain C3H/HeJ were also found to be twice as high as those of C57BL/6J mice. The activities of other tRNA base-specific liver tRNA methyltransferases were very similar in all strains studied. The N2-MeGII activity of the F1 progeny of a cross between C57BL/6J and C3H/HeJ showed levels of activity intermediate to those of the parental strains. Activities of liver N2-MeGII of two inbred strains of mice that differ in their H-2 haplotype (C57BL/10SnJ and the congenic strain B10.BR/SgSnJ) were also compared. Both C57BL/10SnJ and B10.BR/SgSnJ strains exhibited low levels of liver N2-MeGII activity, indicating that H-2 does not directly control the activity of this enzyme.

T-cell-lymphokines and the production and function of accessory cells

The recent purification and cloning of T cell-derived growth factors, should lead to rapid progress in delineating their role in the generation of accessory cells and the regulation of their function. The techniques that have allowed detailed in vitro studies of the T-dependent mast cells, should be generally applicable to other bone-marrow-derived cells. Although the T-dependent mast cell (i.e. P cells) of the mouse appear to have a special propensity to persist in vitro and special techniques that promote the emergence of immortalized clones will probably be necessary to grow useful quantities of other cell-types in vitro using PSF, it should prove possible to develop factor-dependent lines of various bone-marrow-derived accessory cells such as dendritic cells and Langerhans cells. The availability of clonal populations will permit analysis of the interaction of factors such as haematopoietic growth factors, interferon, glucocorticoids and other mediators involved in inflammatory reactions such as the prostaglandins and leukotrienes - not only in the regulation of Ia-antigen expression but also in modulation of other accessory cell functions such as the secretion of IL-1 and perhaps ultimately the processing and presentation of antigens.

Lymphocyte homing in mice: lack of significant alteration when H-2 antigen expression is moderately modified

The part played by MHC antigens on lymphocyte homing has been investigated by inducing modifications of their expression on lymphoid cells. A significant, though moderate, enhancement of H-2 antigen expression has been observed following in vitro treatment of lymphocytes with alpha-IFN. A decrease has been obtained after in vivo treatment of mice with chloramphenicol. These rather moderate alterations of H-2 density (ca. 20-30%, as determined by cytofluorometry) did not induced changes of lymphocyte capacity to home into the different lymphoid organs.

A calmodulin antagonist increases the apparent rate of endocytosis of liposomes bound to MHC molecules via monoclonal antibodies

We have investigated the molecular mechanisms required for endocytosis of MHC-encoded proteins by a cell line, TRH 42, that expresses endogenous murine and introduced human class I molecules. As probes we have used protein A-bearing liposomes which bind to cell surface determinants via monoclonal antibodies. The technique of fluorescence quenching release was used with liposome encapsulated quenched carboxyfluorescein as the marker for endocytosis. We demonstrate that the calmodulin antagonist trifluoperazine (TFP) enhances the apparent rate of endocytosis of liposomes bound to MHC class I molecules. Drugs that interfere with energy metabolism, microfilament organization, or phospholipase A2 activity all block endocytosis both in the presence and absence of TFP. The requirement of extracellular Ca2+ for endocytosis was found to be partial. The implications for the structural and enzymatic requirements of endocytosis of MHC class I molecules are discussed.

Ecotropic and dualtropic mink cell focus-inducing murine leukemia viruses can induce a wide spectrum of H-2 controlled lymphoma types

Neonatal infection of C57BL and BALB/c mice by cloned ecotropic and dualtropic mink cell focus-inducing (MCF) murine leukemia viruses (MuLV) induces a wide spectrum of different lymphomas of T, B, and non-T/non-B cell types. Oncogenic dualtropic MCF viruses and poorly oncogenic ecotropic MuLV act synergistically in lymphomagenesis. Within one mouse strain virus-induced T-cell lymphomas arise earlier than B-cell lymphomas after neonatal inoculation of a single-cloned MuLV. The host genetic constitution, notably the H-2 complex has a marked influence on lymphoma type. This H-2 influence can be explained by an H-2-linked difference in penetration of the thymus early in life by oncogenic thymotropic MuLV, which in turn is correlated with, but not necessarily due to the magnitude of the anti-MuLV antibody response.

Herpetic keratitis in inbred mice

The corneas of four inbred strains of mice (BALB/c, DBA/2, C3H and C57BL/6) were inoculated with the RE strain of herpes simplex virus, type 1. The corneas were examined at frequent intervals and graded on a scale of 0 (clear cornea) to +5 (severe necrotizing stromal keratitis). At 3 weeks postinfection, the mean corneal scores were: DBA/2, 4.0; BALB/c, 2.2; C3H, 0.7; and C57BL/6, 0.15. The differences between the scores are statistically significant (P less than 0.05), except for the C3H and C57BL/6 strains. The order of severity of corneal disease in these mice corresponds to the order of susceptibility to systemic infection found in these same inbred strains. Additional studies of herpetic keratitis in inbred mice should prove helpful in understanding the genetic and immunologic basis of herpetic stromal keratitis.

Immunocytochemical localization of class I H-2 histocompatibility antigens of mouse liver

The subcellular location of class I H-2 histocompatibility antigens was determined for mouse liver using immunocytochemical techniques and correlated with information determined by cell fractionation and analysis in situ. Surface antigens first were localized by standard procedures involving surface labeling with ferritin-labeled antibody. This approach could not be used for internal membranes either in situ or in fractions since the antigens are not expressed at the cytoplasmic surface. For this purpose, thin sections of tissues embedded in Lowicryl were analyzed and quantitated. The in situ analysis confirmed the presence of H-2 antigens on internal membrane compartments as well as on the cell surface and helped rule out the possibility that distributions based on analyses by immunoprecipitation of fractions of internal membranes were influenced greatly by plasma membrane contamination. Quantitation was provided by immunoprecipitation of H-2 antigens from radioiodinated or metabolically labeled isolated and highly purified cell fractions. The findings establish the presence of class I H-2 histocompatibility antigens in endoplasmic reticulum, Golgi apparatus and plasma membrane in the approximate ratios of 1:3:7. No class I H-2 histocompatibility antigens could be detected in mitochondria, salt extracts of isolated membranes or NP-40-insoluble membrane material.

Interaction between insulin receptors and major histocompatibility complex antigens in mouse liver membranes

Insulin receptors from H-2k mouse liver membranes were specifically labelled using a photoreactive insulin analogue coupled to the alpha-subunit (Mr 130,000) of the receptor by ultraviolet-irradiation. Up to 25% of the labelled insulin receptors recovered after membrane solubilization and precipitable by anti-insulin receptor antibodies could be immunoprecipitated by various monoclonal antibodies reacting with H-2Kk antigens. None of these monoclonal antibodies inhibited insulin binding to its receptor. These results show that insulin receptors and H-2Kk antigens interact in liver plasma membranes to form non-covalent complexes. This association between insulin receptors and major histocompatibility complex antigens could be involved in the pathogenesis of certain forms of insulin resistance.

In vitro induction and expression of interleukin 2 receptor in a clonal T helper cell differentiation model

Induction and expression of interleukin 2 (IL 2) receptor have been studied using a poly( Glu60 Ala30 Tyr10 ) (GAT)-specific T cell clone of mouse origin. This clone (52-3) has been characterized and it exhibits functional properties of T helper (TH) cells: it leads to a specific anti-DNP response in the presence of DNP-GAT and DNP-primed B cells and it secretes biological activities which can induce polyclonal B cell proliferation and IgM secretion. In vitro this clone mimics the activation stages of normal T lymphocytes and can be obtained under two states of differentiation. depending on the antigen-specific signal provided by antigen-presenting cells (APC). The expression of IL 2 receptor by this clone has been studied by (i) its response to IL 2, (ii) its capacity to absorb IL 2 bioactivity, and (iii) its reactivity with monoclonal antibody 7D4 specific for mouse IL 2 receptor. All the results indicate that the unstimulated state does not express the IL 2 receptor while the activated state does. Clone 52-3 has been compared with clone 14-1.6 that derives from a TH cell line and expresses the IL 2 receptor constitutively. 52-3 offers a good experimental model for studying in vitro, in a clonal TH cell population, the detailed mechanism of IL 2 receptor induction.

Ir gene control of T and B cell responses to determinants in (Glu Lys Ala) terpolymers

All mice responding to the terpolymer GLA40 make GL, GA and GLA specific antibodies irrespective of their response to GL or GA alone. The mice displayed positive T cell proliferative responses against the homologous terpolymer, but no T cell responses were obtained with GL, which is non-immunogenic in mice. T cells from GLA immune mice, which are also responders to GA, such as mice of H-2 haplotypes a, b, d, k and r, could be stimulated by GA. T cells from GLA immune mice of H-2 haplotypes p and q which are non-responders to GA could not be stimulated by GA. On the other hand, T cells from H-2s mice immune to GLA and which are also responders to GA alone could not be stimulated by GA. Thus mice of H-2 haplotypes p, q and s recognize the terpolymer via 'GLA' determinants alone, whereas mice of H-2 haplotypes a, b, d, k and r may recognize both GA and GLA determinants in GLA terpolymer.

Prolongation of the survival of skin grafts in mice by PUVA treatment

The combined application of psoralen and UVA radiation to skin grafts induced a prolongation of the survival time of the grafts in mice. This was observed using the H-Y barrier, an allogeneic barrier without H-2 disparities, and a strong H-2 incompatible barrier. The effect is probably due to a reduction of antigen-presenting cells, or to other, unknown mechanisms.

Migration patterns and functional activity of cloned cytotoxic T lymphocytes in syngeneic and allogeneic mice

The quantitative distribution of cytolytic T lymphocytes (CTL) generated in mixed leukocyte culture (MLC) and an interleukin-2 (IL-2)-dependent, CTL clone (WRL-A3) was investigated in various tissues of irradiated syngeneic and allogeneic mice. In addition, the ability of the WRL-A3 CTL clone to remain viable and retain antigen specificity following in vivo passage was evaluated. Injection i.v. of 51Cr-labeled cultured CTL resulted in: (1) extensive deposition of cells in the lungs with significantly more lymphocytes being recovered in allogeneic as compared with syngeneic lung tissue; (2) minimal accumulation in spleen with more in syngeneic than in allogeneic tissue; and (3) no localization in blood, femurs, thymus, or lymph nodes. The migration rate of cultured CTL exiting the lung during the first 4 hr was markedly faster in syngeneic than in allogeneic recipients and was directly associated with the distribution of these cells in other tissues at 24 hr. The WRL-A3 CTL clone recovered from irradiated syngeneic and allogeneic lung tissue at 1, 3, 6, 8, and 13 days after i.v. injection remained viable, even though no exogenous IL-2 was administered to the recipient mice. The recovered cells proliferated when recultured with IL-2, and retained their antigen specificity for Qed-1b target cells after in vivo passage. These findings indicate that restricted and undesirable tissue distribution, rather than impaired viability or loss of antigenic specificity, is the major obstacle to successful use of cultured CTL for adoptive immunotherapy of disseminated cancer.

T-cell mediated immunity in murine malaria. I. Induction of T-cell dependent proliferative responses to Plasmodium chabaudi

To investigate the mechanisms of cell mediated immunity to malaria, we studied different systems to measure specific activation of T lymphocytes by P. chabaudi antigens. Mice were primed by subcutaneous administration of parasite antigens followed by co-cultivation of lymphocytes taken from the draining lymph nodes in the presence of the priming antigen. A marked proliferative response was observed which was shown to be antigen specific, T-cell mediated and accessory cell dependent. Continuous T-cell lines were propagated in culture by repetitive restimulation in the presence of antigen and accessory cells, followed by expansion in a conditioned medium containing T-cell growth factors. These lines could be induced to proliferate to the priming antigen only in the presence of syngeneic accessory cells thus indicating that H-2 restriction operates in the recognition of plasmodium antigens by T cells. We also induced parasite specific T cells by the use of an in vitro primary 'education' system. Lymphocytes from unprimed mice were sensitized on parasite-fed macrophages and were then injected subcutaneously into each hind foot pad of syngeneic animals. This led to recruitment of antigen-reactive cells which were assayed in vitro by the ability of lymphocytes taken from the draining popliteal lymph nodes to proliferate in response to the sensitizing antigen. In vivo immunization with Plasmodium antigen fed macrophages also signalled antigen specific T cells that recruited reactive T cells in the draining lymph nodes.

Impaired H-2 expression in B16 melanoma variants

We studied the expression of H-2b alloantigens in three different B16 melanoma lines cultures in vitro. Cell lines were B16-F1 and two cell cultures (named B16-A and B16-B) newly derived from two different in vivo sublines of B16 melanoma. The assays used were in vivo tumour growth in allogeneic (BALB/c and B10.BR) as compared to syngeneic mice, in vitro cell-mediated cytotoxicity by anti-H-2b immune lymphocytes and absorption of anti-H-2b antisera activity. The B16-F1 line was able to efficiently kill allogeneic hosts, could not be lysed by anti-H-2b cytotoxic effectors and did not express any serologically detectable amount of H-2b alloantigens. The B16-A line was H-2 positive during the early in vitro passages, then, at the 8th-10th passages, it acquired the capacity to kill allogeneic hosts, lost the sensitivity to anti-H-2b cytotoxic effectors and the H-2Kb antigens became undetectable The expression of H-2Db was reduced, although at a lower degree. Similar data were obtained with B16-B cells, which after 10 in vitro passages grew and killed allogeneic hosts, showed a decreased sensitivity to cytotoxic anti-H-2b effectors and a very low expression of the K region antigens. The results indicate that H-2 expression is altered in B16 melanoma lines and this may influence the different metastatic capacity of such cells.

Immunoregulation of genetically controlled acquired responses to Leishmania donovani infection in mice: the effects of parasite dose, cyclophosphamide and sublethal irradiation

On a B10 (Lshs) genetic background, the development of acquired T cell mediated immunity to Leishmania donovani infection in mice is under H-2 linked genetic control. Following intravenous inoculation of 10(7) amastigotes three phenotypic patterns of recovery have been described: 'early cure' (H-2r,s), 'cure' (H-2b) and 'non-cure' (H-2d,q,f). In an attempt to determine the immunological basis for this H-2 linked genetic control the effects of varying parasite dose (5 x 10(3) to 5 x 10(7) amastigotes) and of pre-treatments with cyclophosphamide (50 or 200 mg/kg body weight CY) or sublethal irradiation (100 or 550 rad) on the course of infection, and on circulating anti-leishmanial IgG levels, were examined in strains representative of the three phenotypes: B10.D2/n (H-2d), C57BL/10ScSn (H-2b) and B10.RIII (H-2r). It was found that with low parasite doses (5 x 10(3) or 5 x 10(4)) 'non-cure' mice presented a 'cure' profile whilst raising the dose (5 x 10(7)) caused some perturbation of the normal self-curing response in 'cure' (but not 'early cure') mice. The highest dose did not, however, lead to progressive disease in the genetically non-cure strain. For the parasite dose experiments circulating anti-leishmanial IgG levels were higher in the early cure and cure strains than in the H-2d non-cure strain. The higher doses of CY and sublethal irradiation administered prior to infection had a clear prophylactic effect on the non-cure strain with some effect also observed in cure and early cure strains. This was thought to be due to deletion of the precursors of T suppressor (TS) cells suppressing cell-mediated immunity. Resolution of the liver parasite load in pre-treated mice took place despite minimal or undetectable levels of circulating anti-leishmanial IgG. Similarly, the earlier resolution of parasite load in pre-treated cure and early cure mice occurred even though the antibody response was severely reduced. This suggests that the high antibody responses observed in early cure and cure strains do not normally mediate cure and may simply reflect the independent effect of H-2 on T helper function or the humoral response.