A new mouse cell-surface antigen (Ly-m20) controlled by a gene linked to Mls locus and defined by monoclonal antibodies

Five monoclonal antibodies were established by the fusion of mouse myeloma cells (NS.1) with spleen cells from A and (A x C3H/An)F₁ mice hyperimmunized with 70Z/3 tumor cells. These antibodies recognized a new antigenic specificity provisionally called Ly-m20.2. In direct cytotoxicity assays, 60 percent of cells in spleen, 40 percent in lymph node, 50 percent in bone marrow and less than 5 percent in thymus were found to react with three of the five antibodies, whereas the two others yielded somewhat lower cytotoxicity indices. The Ly-m20.2 antigen was also expressed on cells derived from liver and kidney but not on cells derived from brain. As judged from cytotoxicity assays with separated T and B cells, Ly-m20.2 antigen is carried preferentially on B lymphocytes. Direct plaque-forming cells (PFC) were completely eliminated by Ly-m20.2-specific antibody and complement. Linkage tests by analysis in 20 (CBA/J x C3H/An) x C3H/An backcross mice and by segregation analysis of BXH and SWXL recombinant inbred strains indicate close association of the loci controlling Ly-m20.2 and Mls antigens on chromosome 1.Abbreviations used in this paper MLR mixed lymphocyte reaction - MHC major histocompatibility complex - Mls minor lymphocyte-stimulating antigen - Ia I-region associated - PFC plaque-forming cell - SRBC sheep red blood cell - Con A concanavalin A - LPS lipopolysaccharide - GVH graft-versus-host - HVG host-versus-graft - CML cell-mediated lympholysis - LD lymph ocyte-defined - SD serologically defined The prefix m (monoclonal) is used following a suggestion by Klein and co-workers (1979).     

Ly-m19: The Lyb-2 region of mouse chromosome 4 controls a new surface alloantigen

Spleen cells from an SJL mouse immunized with 70'/3 cells, an established pre-B cell line, were fused with cells of the nonsecretor myeloma line NS.1. One established hybridoma cell line (clone K10.6) continuously secreted antibody that recognized a new antigenic specificity tentatively named Ly-m19. This newly found antigen is detectable on both T and B cells. Cytotoxicity assays reveal that 75 percent of the spleen and lymph-node cells, 35 percent of bone-marrow cells, and 15 percent of thymus cells reacted with antibody of clone K10.6. Strains expressing the specificity Ly-m19.1 are characterized by negative reactions and include the strains AKR, CE/J, RF/J, GR/A, SJL, P/J, BDP/J, and LG/J. All other strains so far tested are Ly-m19.2. This strain distribution pattern distinguishes Ly-m19 from any known murine lymphocyte alloantigen, but it parallels the Lyb-2 ^c haplotype. Linkage test of a set of AKXL recombinant inbred strains revealed close linkage of Ly-m19 and Lyb-2 loci on mouse chromosome 4.Abbreviations used in this paper LPS lipopolysaccharide - B6 C57BL/6 - Con-A concanavalin A - MLC mixed-lymphocyte culture The prefix m (monoclonal) is used following a suggestion by Klein and co-workers (1979).     

Ly-m11: TheH-3 region of mouse chromosome 2 controls a new surface alloantigen

Spleen cells from an SJL mouse immunized with B10.S spleen cells were fused with the nonsecretor myeloma line NS.1. One established hybrid cell line continuously secreted antibody that recognized a new antigenic specificity, tentatively called Ly-mll. This newly found antigen is detectable on nearly 100 percent of spleen and lymph-node cells, 70 percent of bone-marrow cells, and 20 percent of thymus cells by direct cytotoxicity assays, and on the cells derived from kidney and liver. Strains that are Ly-mll (+) include C57BL/6, C57BL/10J, B10.S, C57BR/cdJ, C57L/J, and C57BL/KsJ. Other mouse strains so far tested are Ly-m11 (–). The strain distribution pattern distinguished Ly-mll from any known murine lymphocyte alloantigens, but it follows theH-3 ^a haplotype which is defined by skin transplantation. Linkage tests of nine congenic strains ofH-3 and/orH-13/a loci and five recombinant inbred lines including CXB, BXH, AKXL, SWXL, and BXD revealed no recombinations betweensH-3 andLy-m11 loci on chromosome 2. This newly discovered Ly-m11 alloantigen could itself constitute a minor histocompatibility antigen detectable by serological means.Abbreviations used in this paper RI recombinant inbred - H histocompatibility - a non-agouti - B10 C57BL/10Sn The prefix m (monoclonal) is used following a suggestion by Klein and co-workers (1979).     

Ly-m11: the H-3 region of mouse chromosome 2 controls a new surface alloantigen

Spleen cells from an SJL mouse immunized with B10.S spleen cells were fused with the nonsecretor myeloma line NS.1. One established hybrid cell line continuously secreted antibody that recognized a new antigenic specificity, tentatively called "Ly-m11." This newly found antigen is detectable on nearly 100 percent of spleen and lymph-node cells, 70 percent of bone-marrow cells, and 20 percent of thymus cells by direct cytotoxicity assays, and on the cells derived from kidney and liver. Strains that are Ly-m11 (+) include C57BL/6, C57BL/10J, B10.S, C57BR/cdJ, C57L/J, and C57BL/KsJ. Other mouse strains so far tested are Ly-m11 (-). The strain distribution pattern distinguished Ly-m11 from any known murine lymphocyte alloantigens, but it follows the H-3 alpha haplotype which is defined by skin transplantation. Linkage tests of nine congenic strains of H-3 and/or H-13/alpha loci and five recombinant inbred lines including CXB, BXH, AKXL, SWXL, and BXD revealed no recombinations between H-3 and Ly-m11 loci on chromosome 2. This newly discovered Ly-m11 alloantigen could itself constitute a minor histocompatibility antigen detectable by serological means.     

Studies of the mouse Ly-6 alloantigen system

Three monoclonal antibodies were produced by fusing mouse myeloma cell line NS-1 with spleen cells from C3H/An mice hyperimmunized with B6-H-2^k spleen cells. These antibodies recognized an alloantigen displaying a similar strain distribution pattern to the Ly-6.2 and Ala-1.2 alloantigens. Analysis of C×B and B×H recombinant inbred mice revealed close linkage of genes controlling Ly-m6 and Ly-6. The monoclonal antibodies lysed 70 percent of cells in lymph nodes and 60 percent in spleen in direct cytotoxicity assays, but did not lyse significant numbers of cells of thymus and bone marrow. Separated T and B cells were reactive with the antibodies, but T cells were more sensitive to the antibody and complement than B cells. Virtually all cells in cultures of cells activated in the mixed lymphocyte reaction or by Concanavalin A were reactive with the monoclonal antibodies. Direct plaque-forming cells were completely eliminated by the monoclonal antibody and complement. By absorption tests, cells from all organs tested so far (thymus, lymph node, spleen, bone marrow, brain, kidney and liver) were shown to express the Ly-m6 determinant. Tumor cell lines with T, B or stem cell characteristics were reactive with the monoclonal antibody by direct cytotoxicity and absorption assays.     

Characterization of T lymphocyte subsets with monoclonal antibodies: discovery of a distinct marker, Ly-m22, of T suppressor cells

The study of cell surface antigens has accelerated in the few years since the advent of hybridoma technology to the point where many dozens of such markers have now been described. The functional heterogeneity of post-thymic T cells in the immune response, however, still exhibit complexities beyond the resolving power of our current repertoire of marker antigens. In this study, we investigated the surface phenotype of three types of effector T cells: helper cells, nonspecific suppressor cells, and cytotoxic T cells, using four recently discovered alloantigen systems of T cells: Ly-m10, Ly-m18, Ly-m19, and Ly-m22. SRBC-primed spleen cells were used as a source of specific helper T cells, and they were tested by their ability to promote antibody synthesis by B lymphocytes. Concanavalin A-activated suppressor cells were assayed by their ability to inhibit that response. Cytotoxic T cells were activated by alloantigen. We found Ly-m10 to be expressed on all three cell types tested, whereas Ly-m18 and Ly-m19 were absent from all three. Ly-m22, whose controlling locus is closely linked to the Mls region, had a unique distribution, being present solely on suppressor cells. Thus Ly-m22 emerged as a new marker that distinguishes nonspecific T suppressor cells (Ly-m22+) from T helper as well as cytotoxic T cells (Ly-m22-). Ly-m22 is the only antigen besides I-J so far known to be restricted to suppressor cells.     

Endogenous xenotropic murine leukemia virus-related sequences map to chromosomal regions encoding mouse lymphocyte antigens.

DNAs of all inbred mouse strains contain multiple copies (18 to 28 copies per haploid mouse genome) of endogenous xenotropic murine leukemia virus-related sequences detectable by Southern analysis with a xenotropic murine leukemia virus env gene-specific probe. After PvuII digestion, we identified a subset of xenotropic murine leukemia virus-related sequences that are well resolved by agarose gel electrophoresis and can be mapped to specific chromosomes by using recombinant inbred mouse strains. Interestingly, three of six xenotropic proviral loci that we mapped were integrated near genes encoding mouse lymphocyte antigens (Ly-m22, chromosome 1; Ly-m6, chromosome 2; and Ly-m10, chromosome 19) and a fourth xenotropic proviral locus mapped near a gene on chromosome 4 that has a major influence on xenotropic virus cell surface antigen levels. These studies indicate that xenotropic proviral loci are located on many different mouse chromosomes and may be useful markers for molecularly cloning and characterizing regions of the mouse genome important in lymphocyte development.     

Ala-1: A murine alloantigen of activated lymphocytes

Ala-1 (activated lymphocyte antigen-1) is a murine alloantigen expressed on mitogen-stimulated peripheral T and B cells. C3H/An mice were immunized with PHA-stimulated C58 lymphocytes; reciprocal immunizations were also performed. After multiple absorptions to remove unwanted antibody specificities, the antiserum did not lyse thymocytes, lymph node, or spleen cells, but killed more than 90% of Con A-stimulated T cells and more than 90% of LPS-stimulated B cells in cytotoxicity tests. Quantitative absorption studies confirmed that thymocytes are Ala-1^–, but revealed the presence of some Ala-1 antigen in normal lymph node and spleen populations. The strain distribution of Ala-1 was determined for 23 inbred strains. The reactions of the two reciprocal antisera (C3H anti-C58, and C58 anti-C3H) were mutually exclusive on all strains tested, indicating that the antisera probably recognize antithetical forms of Ala-1. Since thymocytes cultured with Con A do not express Ala-1, whereas peripheral mitogen-stimulated cells do, we propose that Ala-1 is a differentiation antigen, the expression of which is restricted to the late stages of development of T and B cells.Abbreviations used in this paper are Con A concanavalin A - PHA phytohemagglutinin - LPS lipopolysaccharide - C complement - BSA bovine serum albumin - B6 C57BL/6 mice - FBS fetal bovine serum     

Expression of Ly-6 on activated T and B cells: Possible identity with Ala-1

The antigens Ala-1 and Ly-6 were first thought to be different on the grounds that Ala-1 was present only on activated T and B lymphocytes while Ly-6 was present only on post-thymic T lymphocytes. In this paper, it is shown that Ly-6 is expressed on activated B cells, including PFC and LPS blasts, and that after typing of several recombinant inbred lines,Ala-1 andLy-6 remain genetically inseparable. Based on available data, it is most likely that Ly-6 is in fact Ala-1, although further testing is required to confirm the absence of Ly-6 from nonactivated lymphocytes.Abbreviations used in this paper Con A concavalin A - LPS lipopolysaccharide - SRBC sheep red blood cells - PFC plaque-forming cells - RI recombinant inbred strains - B6 C57BL/6 mice     

Studies of the mouse Ly-6 alloantigen system

The discovery of several monoclonal antibodies provided the impetus to revisit the Ly-6 group of antigens. Our serological data point to the existence of at least five separate Ly-6 antigens. They are distinguished by the patterns of their tissue expression as (1) the classical Ly-6 alloantigen of peripheral lymphocytes (Ly-m6.2A), (2) a bone marrow cell-restricted antigen (Ly-m6.2B), (3) an antigen shared by bone marrow cells and peripheral lymphocytes (Lym6.2C, possibly identical with H9/25),(4) an antigen expressed on bone marrow cells, thymocytes, and peripheral lymphocytes (Ly-m6.2D), and (5) an antigen occurring exclusively on lymphoblasts (Ly-m6.IE, similar to Ala-1). ThB is a sixth distinct antigen of the group. The assumption that separate antigens exist is supported by distinctive distribution patterns in normal and neoplastic tissues. The genes controlling Ly-6 antigens are closely linked, as they are transmitted as two haplotypes only. One incidence of a crossover within the Ly-6 region was observed: the Ly-6B.2 alloantigen was expressed in NZB mice, which type Ly-6.1 for other Ly-6 specificities.     

Biochemical characterization of murine lymphoid alloantigen Ly-m20.2, a cell surface marker controlled by a gene linked to the Mls locus

The lymphoid alloantigen Ly-m20.2 is expressed on the majority of B cells and a wide variety of hemopoietic cells including stem cells. However, it is not detectable on T lymphocytes. Genetic studies indicate that expression of Ly-m20.2 is controlled by a gene(s) closely linked to the M1s locus. Our present biochemical analysis shows that Ly-m20.2 is a monomeric glycoprotein of 55,000 to 60,000 daltons, with no detectable intramolecular disulfide bonds. The Ly-m20.2 molecules of tissues and clonal cell lines exhibit size and charge heterogeneity that can be eliminated by the complete removal of N-linked sugars with the enzyme endo-F or by inhibiting glycosylation with tunicamycin. The resulting unglycosylated Ly-m20.2 molecule migrates as a single band of 40,000 daltons in SDS-gels and behaves as a single charge species in IEF. The Ly-m20.2 antigen was compared biochemically with two other alloantigens: LyM-1, an alloantigen whose expression is also controlled by gene(s) tightly linked to the M1s locus, and Ly-17.1, an alloantigen serologically allelic to the Ly-m20.2 antigen. Immunoprecipitates obtained with the respective LyM-1 and Ly-17.1 antisera yielded similar 55,000 to 60,000 dalton molecules from cells of the appropriate mouse strains. In the case of LyM-1, sequential immunoprecipitation provided evidence that Ly-m20.2 and LyM-1 are identical.     

A novel MHC class I-related molecule expressed on mouse thymic stroma cells and mature lymphocytes

A monoclonal antibody (mAb) TP-3 has been established by immunizing rats with the BALB/c mouse thymic epithelial cell line TEL-2. The TP-3 antigen is expressed on stroma cells of thymus, spleen, and lymph node in syngeneic BALB/c mice (H-2 ^d ). This antigen is also expressed at a low level on the cell surface of immature thymocytes, and at a high level on mature T and B cells. In allogeneic mice such as C57BL/6 (H-2 ^b ) or C3H (H-2 ^k ), no cells expressed the TP-3 antigen. Using H-2 congenic mice, reactivity with mAb TP-3 was found to map to a region of H-2D ^d L ^d or between D ^d and Qa, suggesting that TP-3 is a major histocompatibility complex (MHC) class I antigen. However, immunoprecipitation analysis indicated that this antigen is not identical to the classical mouse class I molecules in terms of molecular size, antigenicity, and tissue distribution.     

Biological characterization of T and B lymphocytes separated from normal mouse spleen by a physical adherence column method

The capacity of spleen cell populations enriched for T and B lymphocytes by a physical adherence column method to respond in vitro to phytomitogens and allogeneic lymphocytes was determined. Column filtrate cells (T lymphocytes) responded well to phytohaemagglutinin- and mitomycin-C-treated allogeneic spleen cells, but poorly to pokeweed mitogen. Adherent cell populations from the column (B and some T lymphocytes) responded well to pokeweed mitogen, but poorly to phytohaemagglutinin- and mitomycin-C-treated allogeneic cells.Purified peripheral T lymphocytes prepared from normal mouse spleen by the column method reconstituted the depleted in vitro antibody response to the thymic-dependent SRBC antigen of all B lymphocyte sources tested, namely, spleen cells from congenitally athymic mice, neonatally thymectomized mice, and adult thymectomized mice which had been reconstituted with bone marrow, and a lymphocyte population prepared by incubating spleen cells with anti-θ serum and complement. When transferred with sheep erythrocytes to congenitally athymic mice, purified peripheral T cells restored the in vivo IgM and IgG responses of these animals. These results confirm that the column filtrate is a thymus derived subpopulation of cells capable of cell-mediated immunity and cooperation with B lymphocytes in humoral immunity both in vitro and in vivo.     

Definition of new alloantigens encoded by genes in the Ly-6 complex

Three alloantigens encoded by Ly-6-linked genes are defined by monoclonal antibodies. The Ly-27.2 antigen is defined by antibody 5075-19.1, Ly-28.2 by 5075-3.6, -12.1, -16.10 and by 5095-16.6. The strain distribution pattern of these antibodies is the same and identical with Ly-6.2. However the tissue distribution of these antigens is unique and distinguishes these antigens from the Ly-6.2 antigen or any known antigen encoded by Ly-6-linked genes. Ly-27.2 is present on all thymocytes, T cells, and B cells but is absent from bone marrow cells, whereas Ly-28.2 is absent from most thymocytes and is present on a subpopulation of T cells and B cells but is found on 60–70% of bone marrow cells. No recombination between the Ly-6/Ly-27/Ly-28 loci was found in linkage studies using 41 recombinant inbred strains and 57 backcross mice and indicates very close linkage of these genes. In addition, close linkage to 24 minor histocompatibility genes was excluded using the Bailey HW bilineal congenic mice. The data presented indicate that either the Ly-6 complex is composed of a family of tightly linked genes or the antigens are the products of a single gene that undergoes extensive modification during differentiation.     

T(Iat)- and B(Iab)-cell alloantigens determined by theH-2 linkedI region in mice

The specificity of an antiserum directed againstI region associated (Ia) antigens is described. The serum was raised in (DBA/1×B10.D2)F₁ mice against lymphocytes of AQR mice, differing from the responder for theI region only. The serum reacts with Ia antigens expressed on B cells (Iab) as well as with Ia antigens expressed on T cells (Iat). Absorption studies indicate that B cells possess at least two Ia antigens, and one of these is shared by T cells. However, this shared antigen is not present on the surface of lymphocytes of thymectomized mice. Analysis of the strain distribution of Iab and Iat antigens revealed that the Iab antigens are present on lymphocytes of mice carrying theIA ^k subregion and that the Iat antigens are present on lymphocytes of mice carryingI region genes of theH-2 ^k haplotype located between theIA andIB subregions. This conclusion is based on the analysis of the antiserum's reactivity with T and B cells of the strains B10.A(2R), B10.A(4R) and B10.HTT: the serum reacts with B and T cells of B10.A(2R) but only with B cells of B10.A(4R) mice and only weakly with T cells of B10.HTT mice.Abbreviations ALG antimouse lymphocyte globulin from rabbits - B cells bone marrow derived lymphocytes - B10 C57BL/10Sn mice - D1D2F₁ (DBA/1×B10.D2)F₁ hybrid mice - GVHR graft-vs-host reaction - Ia I region associated antigen - Iab on B cells - Iat on T cells - MLR mixed lymphocyte reaction - T cells thymus-derived lymphocytes - Thy-1 thymus antigen 1, formerly called theta - Tx-Lyc lymphocytes of thymectomized, ALG treated, lethally irradiated and anti-Thy-1 treated bone marrow reconstituted mice - 2R B10.A(2R)/SgSn mice - 4R B10.A(4R) mice     

Immunodominance in the T cell response to multiple non-H-2 histocompatibility antigens. IV. Partial tissue distribution and mapping of immunodominant antigens

The immunization of C57BL/6 responder mice with spleen cells from H-2-matched BALB.B donors, which differ by multiple non-H-2 histocompatibility (H) antigens, results in the generation of cytotoxic T lymphocytes (CTL) that are specific for only a limited number of immunodominant antigens. Previous analysis of the genes encoding these dominant antigens has not mapped these genes to any of the non-H-2 H loci defined by congenic strains. It would have been expected that the histogenetic techniques employed for congenic strain selection would have preferentially identified the "strongest" H antigens. Therefore, we have investigated the possibility that immunodominant antigens do not belong to the class of non-H-2 H antigens encoded by genes mapping to H loci defined and mapped by congenic strains. The first experiments were aimed at identifying antigens that were expressed by independently derived inbred strains and were cross-reactive with the immunodominant cytotoxic T cell target (CTT-1) antigen of BALB.B. Strong cross-reaction with the C3H.SW (H-2b) strain was observed; the C3H gene encoding this antigen was mapped with BXH recombinant inbred strains. Contrary to the mapping of the CTT-1 gene to chromosome 1 in BALB.B, the C3H gene was shown to map to either chromosome 4 or chromosome 7. This result indicates that identical, or at least extensively cross-reactive, non-H-2 antigens may be encoded by genes mapping to independently segregating loci in different inbred strains. The tissue distribution of immunodominant antigens was approached by determining the reactivity of CTL specific for these antigens with either lymphoid-derived or fibroblast-derived targets. These CTL effectively lysed lymphoblast and lymphoid tumor targets but did not lyse an SV40-transformed fibroblast line that was shown to be efficiently lysed by CTL specific for non-H-2 H antigens defined by congenic strains. Therefore, it was concluded that immunodominant antigens detected by B6 anti-BALB.B CTL have a restricted tissue distribution in comparison to non-H-2 H antigens defined by congenic strains. The implications of these results for our understanding of the origin and heterogeneity of non-H-2 cell-surface antigen recognized by effector T cells are discussed.     

T lymphocyte-dependent B lymphocyte proliferative response to antigen. II. Induction of polyclonal B lymphocyte activation of normal B cells and of Lyb-5- B cells from xid mice via recognition of self-IA antigens

We extended our investigations into the genetic requirements and antigen dependence for the induction of polyclonal B lymphocyte proliferation by primed T lymphocytes. By using recombinant inbred mouse strains and antigen-specific T lymphocyte clones that lack alloreactivity, the genetic requirement was mapped to the IA subregion of the MHC. Furthermore, approaches that prevented or limited the accessibility of antigens to the B lymphocyte surface demonstrated that antigen binding onto the B lymphocyte surface was probably not necessary for induction of B lymphocyte proliferation. These experiments suggest strongly that T lymphocyte recognition of B lymphocyte Ia molecules in the absence of sIg cross-linking or in the absence of antigen bound nonspecifically to B lymphocytes can cause cellular activation. Similar T lymphocyte-dependent B lymphocyte activation was seen when Lyb-5- cells from CBA/N mice with the xid defect were cultured. Increases in the number of cells secreting immunoglobulins could be detected in the proliferating B lymphocyte cultures, suggesting that the culture conditions had fulfilled the requirements for B lymphocyte differentiation into antibody-producing cells. Although anti-Ig did not interfere with the B lymphocyte proliferative responses, it did diminish the number of cells secreting immunoglobulins. The implications of these experiments in extending our understanding of the activation pathway of Lyb-5- and Lyb-5+ B lymphocytes are discussed.     

Production of BSF-1 during an in vivo, T-dependent immune response

BSF-1, a cytokine produced by some T lymphocyte tumors, has been shown to act with anti-Ig antibodies to stimulate B lymphocyte proliferation, to independently induce resting B lymphocytes to increase their expression of surface Ia antigen, and to induce some activated B lymphocytes to differentiate into IgG1- or IgE-secreting cells. To determine whether BSF-1 might be secreted by normal lymphoid cells in the course of a physiologic immune response, BALB/c mice were injected with an affinity-purified goat antibody to mouse IgD (GaM delta), which induces the generation of a large, polyclonal T-dependent IgG1 response; 4-hr culture supernatants of spleen cells from these mice were prepared, and these supernatants were assayed for BSF-1 activity by analyzing their ability to induce BALB/c nu/nu spleen cells to increase their expression of cell surface Ia in vitro. Culture supernatants of unfractionated spleen cells removed from mice 4 to 8 days after GaM delta antibody injection induced substantial increases in B lymphocyte surface Ia expression; these increases were blocked by a monoclonal anti-BSF-1 antibody. Culture supernatants of spleen cells from untreated BALB/c mice or from untreated or GaM delta antibody-treated BALB/c nu/nu mice induced small to moderate increases in B cell surface Ia expression, and GaM delta antibody itself induced large increases in B cell surface Ia expression; however, these increases were not significantly blocked by a monoclonal anti-BSF-1 antibody. A culture supernatant of T cell-enriched spleen cells from untreated mice induced small increases in B cell surface Ia expression that were inhibited by anti-BSF-1 antibody, as was the larger increase in B cell Ia expression induced by a culture supernatant of T cell-enriched spleen cells from mice sacrificed 3 days after GaM delta injection. On the other hand, T cell-depleted spleen cells from BALB/c mice injected with GaM delta antibody 7 days before sacrifice failed to generate culture supernatants with BSF-1 activity. Supernatants prepared from spleen cells taken from untreated mice or mice treated with GaM delta antibody 1 to 3 days before sacrifice did not block the ability of purified BSF-1 to induce an increase in B cell surface Ia expression, and thus did not contain inhibitors of BSF-1 activity.(ABSTRACT TRUNCATED AT 400 WORDS)     

A new mouse lymphoid alloantigen (Lgp100) recognized by a monoclonal rat antibody

A new genetically polymorphic cell surface antigen recognized by a monoclonal rat anti-mouse antibody is expressed on mouse lymphoid cells. Fluorescence analysis on the fluorescence-activated cell sorter (FACS) locates the antigen on thymocytes, lymph node cells, and both T and B cells in the spleen. It also appears on approximately 40% of cells in the bone marrow.Immune precipitations from surface iodinated spleen cells followed by 2-D gel electrophoresis demonstrate that the antigen is a glycoprotein of approximately 100,000 daltons. Since it is expressed in all lymphoid tissues and on both T and B cells, we designate it lymphoid glycoprotein 100 (Lgp100).Strains with Lgp100 include A/J, AKR/J, AKR/Cu, BALB/c, 129/J, CBA/N, C3H/HeJ, CBA/2J, and SJL/J. Strains with no detectable antigen include C57BL/6J, C57BL/10J, C57BR/cdJ, C57L/J, and C58/J. Intercrosses and backcrosses establish a pair of alleles, a positive and a negative one, at a single locus. Heterozygotes display about 50% as much antigen as homozygotes by quantitative membrane immunofluorescence on the FACS. Tests for Lgp100 in 35 recombinant inbred strains from three crosses (CXB, BXB, and BXH) locate this locus on chromosome 1, closely linked to theMls locus.     

Biological response modifiers (BRM) as antigens

In order to investigate tumoricidal effector cells in therapy by biological response modifiers (BRM) such asPropionibacterium acnes, bacillus Calmette-Guérin (BCG),Streptococcus pyogenes and a protein-bound polysaccharide (PSK), we established T cell lines specific for each BRM from BALB/c mice immunized with the corresponding BRM. These T cell lines proliferated and produced interleukin-2-(IL-2) and/or IL-4, but only in the presence of the relevant BRM and BALB/c spleen cells as the antigen and antigen-presenting cells respectively. Cross-functional experiments indicated that each BRM acts as a nominal antigen, but not as a non-specific immunostimulator. In addition, the T cell lines killed Ia-positive syngeneic B lymphoma cells, but only in the presence of the relevant BRM. These experiments excluded the possibility of cytotoxic effects by each BRM. The T cell lines and clones also killed Ia-negative bystander target cells, but only in the presence of both a relevant antigen and antigen-presenting cells. The T cell clones specific forS. pyogenes orP. acnes tested were Thy1⁺, L3T4⁺ and Lyt2^–. These results indicate that some BRM exert tumoricidal activity by inducing T cells that recognize them as an antigen and kill tumor cells in an antigen-specific manner. The T cells killed tumor targets in either a tumor-necrosis-factor(TNF)-dependent or a TNF-independent manner. The mediator of the latter pathway remains to be elucidated.