bluuebunny/crossref_metadata_2025 huggingface dataset:
Recognition of polymorphic H-2 domains by T lymphocytes. I. Functional role of different H-2 domains for the generation of alloreactive cytotoxic T lymphocytes and determination of precursor frequencies.
Authors: Weyand C , Goronzy J , Hämmerling G J
Published: June 2004

In the present communication, the repertoire of alloreactive cytotoxic T lymphocytes (CTL) clones was quantitatively investigated by limiting dilution analysis and by target inhibition with a panel of monoclonal antibodies (mAb). These mAb have previously been shown to define two distinct alloantigenic domains, A and B, on the H-2Kk molecule. The Poisson distribution analysis of H-2Kk-specific CTL clones generated in a limiting dilution system revealed three CTL populations with different precursor frequencies. The high frequent population is suppressed by an unknown suppressive mechanism that allows less frequent CTL populations to become visible. Target inhibition studies with a panel of Kk-specific mAb showed that these CTL populations differ not only in their precursor frequency but also in their specificity for different H-2 epitopes on the Kk molecule. Thus clones of the high frequency population are almost exclusively specific for determinants within domain A. In contrast, the low frequency population displays predominant specificity for determinants of domain B, while the population with medium frequency is blocked equally well by mAb against either domains A or B. Each mAb blocked only a fraction of clones indicating that each CTL subpopulation may consist of a large number of clonotypes with specificity for different H-2 epitopes. The data suggest that CTL recognize basically the same polymorphic domains on the H-2Kk molecule defined by antibodies, and they show that regulatory mechanisms determine the expressed repertoire in CTL populations.
Receptor for immunoglobulin Fc on pathogenic but not on nonpathogenic protozoa of the Trypanosomatidae.
Authors: De Miranda-Santos I K , Campos-Neto A
Published: June 2004

Members of the Trypanosomatidae were studied for their ability to acquire host IgG through a possible Fc receptor. A simple rosette test was devised in which the different species and forms of protozoa were mixed with SRBC sensitized with subagglutinating does of IgG, IgM, and F (ab') 2 anti-SRBC, and the pelleted mixture was observed for the number of clumps (rosettes) formed between the parasites and SRBC. Rosettes were formed between parasites and SRBC sensitized with IgG but not with IgM or F(ab')2, indicating the presence of a receptor for IgG Fc. The specificity of this receptor for Fc was confirmed by inhibition experiments with normal rabbit aggregated gammaglobulins or with purified normal rabbit Fc. The receptor is sensitive to treatment with trypsin but regenerates after a short period of incubation (1 h), which indicates that it is synthesized by the parasite itself. Interesting was the observation that only pathogenic members of the Trypanosomatidae formed rosettes with sensitized SRBC. In none of the nonpathogenic forms studied could we demonstrate the Fc receptor. Also important was the finding that freshly isolated blood stream forms of Trypanosoma cruzi from infected mice did not form rosettes. However, after trypsinization, these forms clearly displayed the ability to do so, possibly indicating a previous acquisition of the host IgG by the parasites in the mouse blood stream. These findings point to a possible and important means of parasite evasion of the host immune response by masking their surface with host IgG.
Generation of functional human T cell hybrids.
Authors: Irigoyen O , Rizzolo P V , Thomas Y , Rogozinski L , Chess L
Published: June 2004

Human T cell hybrids were generated by fusing lectin-activated normal and leukemic human T cells with an aminopterin-sensitive human T cell line. This mutant cell line, designated CEM-T15, was derived from the human T cell line CEM after chemical mutagenesis with ethane methylsulfonate and subsequent culture in medium containing 6-thioguanine. After polyethylene glycol-induced fusion, the cells were cultured in hypoxanthine-aminopterin-thymidine selective medium. More than 5 wk after fusion, evidence for successful hybridization was obtained by three independent criteria: (a) The majority of the cultures contained cells expressing the OKT3 surface antigen: this antigen is expressed on normal T cells but not on CEM-T15 cells. (b) Most of the cultures contained polyploid cells. (c) Some of the cultures provided helper activity in the generation of antibody-forming cells. This functional activity is absent from the CEM-T15 parental cell line. Evidence for functional stability of the hybrids greater than 20 wk after fusion was provided by several clones that not only continue growing exponentially but also maintain expression of OKT3 surface antigen and high levels of helper function. These T cell hybrids constructed using antigen-specific human T cells should be of considerable importance in further studies of the immunobiology of human T cells.
Type II collagen-induced arthritis in rats. Passive transfer with serum and evidence that IgG anticollagen antibodies can cause arthritis.
Authors: Stuart J M , Cremer M A , Townes A S , Kang A H
Published: June 2004

We have found that serum from rats with type II collagen-induced arthritis, when fractionated with 50% ammonium sulfate and concentrated, would transfer arthritis to nonimmunized recipients. The arthritis in recipients developed within 18-72 h and displayed all of the major histopathologic characteristics of the early lesion in immunized animals but was transient and less severe. Although consideration was given to the possibility that a circulating immune complex was involved, no evidence of such a complex was detected. Further fractionation of the serum yielded an IgG anticollagen antibody that was fully active in transferring disease. The antibody's reaction was inhibited by the native bovine type II collagen used for immunization of donors and the antibody strongly cross-reacted with homologous type II collage but not with denatured collagen. These studies demonstrate that arthritis in rats can be induced with anti-type II collagen antibodies and suggest that an autoimmune process is involved. Because antibodies to collagen have also been detected in human rheumatic diseases, further investigation of the characteristics of collagen antibodies capable of inducing arthritis seems warranted.
Two distinct allotypic determinants on the antigen-specific suppressor and enhancing T cell factors that are encoded by genes linked to the immunoglobulin heavy chain locus.
Authors: Tokuhisa T , Taniguchi M
Published: June 2004

The alloantiserum was raised in BALB/c (H-2d, Igh-1a) mice hyperimmunized with spleen cells of Igh allotype congenic mice, CB-20 (H-2d, Igh-1b). It was found to define the new allotypic determinants (distinct from B cell Igh constant region determinants: Igh allotype) expressed only on a small population of T cells belonging to the Thy-1 dull-stained Lyt-2- or Lyt-2+ population of Igh-1b mice. Genes coding for the determinants were shown to be accommodated somewhere in the right side of the Igh variable region gene (Igh-V) cluster, as the antibody activity was completely absorbed with BAB-14 thymocytes. It was also demonstrated that the products detected by the antiserum represent the allotypic determinants (probably constant region determinants) on the antigen-binding moiety of the antigen-specific augmenting (TaF) and suppressor (TsF) T cell factors. Moreover, determinants on TsF were found to be distinct from those on TaF. Therefore, it can be suggested that the two genes coding for the T cell allodeterminants (distinct from those of the B cell Igh) are located in the right side of the B cell Igh-V on the 12th chromosome, and that both encode the antigen-recognition units of the functionally distinct T cell factors.
In vitro effects of 4-hydroperoxycyclophosphamide on human immunoregulatory T subset function. I. Selective effects on lymphocyte function in T-B cell collaboration.
Authors: Ozer H , Cowens J W , Colvin M , Nussbaum-Blumenson A , Sheedy D
Published: June 2004

The alkylating agent cyclophosphamide may suppress or enhance immune responses in vivo but is inactive in vitro unless metabolized by microsomal enzyme activation. 4-hydroperoxycyclophosphamide (4-HC) is a synthetic compound that is spontaneously converted in aqueous solution to the active metabolites. In this report, we examined the in vitro sensitivity of functional human T cell subsets to 4-HC in a polyclonal B cell differentiation assay and in the generation of mitogen-induced suppressor cells for effector B cell function. Con A-induced T suppression of B cell differentiation is completely abrogated by a 1-h pretreatment of T cells at very low concentrations of between 10(-2) and 20 nmol/ml, whereas inducer T cell function is sensitive only to concentrations in greater than 40 nmol/ml. The effects of 4-HC on suppressor T cells appear to occur at concentrations that do not result in DNA cross-linking or decreased blastogenesis. Con A-induced T suppressors are generated from within the OKT4+, OKT8- subset and are sensitive to low-dose 4-HC only before activation, whereas differentiated suppressor cells are resistant to concentrations in greater than 80 nmol/ml. Low-dose 4-HC pretreatment of the B cell population results in abrogation of immunoglobulin secretion when treated B cells are cocultured with unfractionated T cells, however, this effect is completely reversible if pretreated B cells are cocultured with T cells devoid of suppressor activity. These results demonstrate that human presuppressor cells for B-effector function differentiate in response to Con A from the OKT4+, OKT8- subset and are exquisitely sensitive to low concentrations of CYP whereas mature suppressor and inducer functions are resistant to all but very high concentrations in vitro. The differential sensitivity of functional T and B cell subsets to 4-HC in vitro can be a very useful probe in dissecting immunoregulatory interactions with man.
Restoration of immunogenicity to passenger cell-depleted kidney allografts by the addition of donor strain dendritic cells.
Authors: Lechler R I , Batchelor J R
Published: June 2004

The immunogenicity of long-surviving, enhanced (AS X AUG)F1 renal allografts retransplanted into secondary AS recipients was restored by the injection of small numbers of donor strain dendritic cells derived from afferent lymph. Whereas 1 X 10(4) to 5 X 10(4) dendritic cells were able to trigger an acute rejection response, neither the passenger volume of donor strain blood nor 5 X 10(6) T or B lymphocytes were able to do so, thereby demonstrating more than a 100-fold difference in immunogenic potency. It is concluded that intrarenal dendritic cells provide the major immunogenic stimulus of a kidney allograft. These results suggest that the antigenic strength of major histocompatibility complex-incompatible tissue correlates with the content of donor strain dendritic cells. They also provide further evidence that antigens of the major histocompatibility complex behave like conventional antigens unless they are on the surface of allogeneic dendritic cells.
During lymphatic regeneration, precursors for major histocompatibility complex-restricted cytotoxic T cells appear before alloreactive precursors.
Authors: Hurme M , Sihvola M , Bång B
Published: June 2004

Mice were injected with a sublethal dose of cyclophosphamide (Cy) (300 mg/kg), and the appearance of the capacity of the regenerating spleen to form cytotoxic T lymphocytes (CTL) in response against 2,4,6 trinitrophenyl-coupled syngeneic cells or against allogeneic cells was followed. It was found that 8 da after Cy injection, the spleen contained cells that could give rise to CTL, but only 2,4,6 trinitrophenyl-specific CTL responses could be obtained at this stage. A low alloresponse was first seen 2 wk after Cy injection.
Role of Ia antigens in graft vs. host reactions. II. Molecular and functional analysis of T cell alloreactivity by the characterization of host Ia antigens on alloactivated donor T cells.
Authors: Delovitch T L , Harris J F , Battistella R , Kaufman K
Published: June 2004

Graft vs. host response (GVHR)-activated donor T cells bind to stimulatory host cell-derived Ia antigens. Radioimmune cell-binding assays demonstrate that activated donor T cells acquire both host I-A and I-E alloantigens on their surface. Approximately threefold to fivefold less I-E products than I-A products are transferred. Immunoprecipitation and one-dimensional and two-dimensional gel electrophoresis analyses show that radioiodinated alpha and beta polypeptide chains of both I-A and I-E-encoded host Ia molecules may be transferred in an apparently structurally unaltered form from host cells to donor cells. Biosynthetic studies indicate that [35S]methionine-labeled activated donor T cells do not synthesize Ia antigens of the donor haplotype. Functional analyses with fluorescence-activated cell sorter sorted donor T cell subpopulations show that donor T cells that bind host I-A antigens preferentially cooperate with nonimmune host B cells. Donor T cells that do not bind detectable amounts of host I-A antigens preferentially help nonimmune donor B cells. By contrast, donor T cells that either bind or do not bind host I-A antigens display no H-2-restricted interaction and help both donor and host immune B cells. These data reveal that the Ia antigen-binding specificity of distinct functional subpopulations of alloactivated donor T cells regulates their I-region-restricted (self or allo) helper activity for nonimmune B cells but not immune B cells. Furthermore, they suggest that T cell-macrophage and T cell-B cell collaboration is mediated by a complementary anti-Ia:Ia receptor:ligand type of interaction in which the receptor of a T cell binds to the ligand of an antigen-presenting macrophage and/or B cell.
Phenotypic and functional properties of murine thymocytes. I. Precursors of cytolytic T lymphocytes and interleukin 2-producing cells are all contained within a subpopulation of "mature" thymocytes as analyzed by monoclonal antibodies and flow microfluorometry
Authors: Ceredig R , Glasebrook AL , MacDonald HR
Published: June 2004

The correlation between surface phenotype and function in subpopulations of murine thymocytes has been investigated using flow microfluorometry (FMF). C57BL/6 thymocytes stained with monoclonal antibodies directed against Lyt-2, H-2K(b), and Thy-l.2 and passed on an FACS II flow cytometer could be resolved into at least four distinct subpopulations on the basis of fluorescence and forward light scatter (FLS) measurements. (a) Medium-sized Lyt-2(+) cells that stained strongly with H-2K(b) and weakly with Thy-l.2 (5 percent of total cells); (b) medium-sized Lyt-2(-) cells with other properties as in (a) (10 percent); (c) small Lyt-2(+) cells that stained weakly with H-2K(b) and strongly with Thy-l.2 (60 percent); and (d) large Lyt-2(+) cells that stained weakly with H-2K(b) and very strongly with Thy- 1.2 (23 percent). Cortisone-resistant thymocytes (CRT) were found to correspond phenotypically to populations (a) and (b).

The distribution of cytolytic T lymphocyte precursors (CTL-P) directed against H-2(d) alloantigens in subpopulations of C57BL/6 thymocytes that had been sorted according to the phenotypic criteria described above was then investigated. CTL-P in sorted and control populations were quantitated by limiting dilution analysis of mixed leukocyte microcultures established in an excess of interleukin 2 (IL-2). These studies established that all thymus CTL-P could be quantitatively recovered in a subpopulation of cells that was cortisone-resistant, medium-sized, Lyt-2(+), H-2K(b+), and weakly stained with Thy-l.2.

In parallel studies, the production of IL-2 by subpopulations of C57BL/6 thymocytes was quantitatively assessed using a recently developed sensitive microassay system. Graded numbers of sorted or control thymocytes were stimulated with irradiated T cell-depleted allogeneic cells and assayed for their ability to support the growth of an IL-2-dependent cytolytic T lymphocyte clone. Using this method, IL-2 production was found to reside entirely in a subpopulation of cortisone-resistant, medium-sized Lyt-2(-) thymocytes. Further phenotypic analysis of this subpopulation of cells indicated that it was homogeneously H-2K(b+) and weakly staining with Thy- 1.2. Taken together with the CTL-P results, these data directly demonstrate that a subpopulation of thymocytes with a mature phenotype (i.e., cortisone- resistant, medium-sized, H-2K(b+), and weakly staining with Thy-l.2) accounts for all the functional activity in the thymus. Reasons for the apparent discrepancy between these results and other recent studies will be discussed.
Influence of the major histocompatibility complex on the repertoire of allospecific cytolytic T lymphocytes.
Authors: Sherman L A
Published: June 2004

Superimposed on the heterogeneous anti-H-2Kb cytolytic T lymphocyte (CTL) receptor repertoire of allogeneic murine strains are reactivities that recur with high frequency amongst individuals of any given strain. These receptor specificities represent phenotypic markers of the CTL repertoire and, as such, have been used to compare receptor repertoires of genetically disparate strains. The results demonstrate that congenic strains differing only in the MHC (B10.D2 and B10.BR) differ significantly in their H-2Kb-specific CTL repertoires. This finding clearly demonstrates a role for the MHC in determination of the CTL precursor repertoire. The mechanism by which MHC influences CTL specificity was explored through analysis of the anti-H-2Kb repertoire of (B10.BR X B10.D2)F1 hybrids. Because at least one recurrent parental specificity has found to be recurrent in F1 progeny as well, the findings indicate that MHC-specific tolerance cannot be solely responsible for repertiore differences between MHC-disparate strains. In addition, the F1 repertoire is characterized by the emergence of several nonparental recurrent specificities.
Ia antigen-bearing B cell tumor lines can present protein antigen and alloantigen in a major histocompatibility complex-restricted fashion to antigen-reactive T cells.
Authors: Glimcher L H , Kim K J , Green I , Paul W E
Published: June 2004

Several Ia-positive BALB/c B cell tumor lines were screened for their ability to present alloantigen and protein antigens to alloreactive and antigen-reactive T cells. Of six Ia-positive tumor lines studied, three were found to be effective as antigen presenting cells (APC). Indeed, on a per cell basis, one of the stimulatory lines, A20.3, was substantially more effective than whole spleen cells. The other three lines, although Ia-positive, were nonstimulatory. A20.3 was chosen for further study. This tumor appeared to behave like the conventional APC because (a) the tumor cells presented alloantigen, (b) they presented protein antigen in an MHC-restricted fashion to both primed donor T cells and to long-term continuous T cell lines, (c) alloantigen presentation was blocked by the inclusion of an anti-Ia antibody in the culture system, and (d) A20.3 cells could be effectively pulsed with antigen, although the continuous presence of antigen in the culture system resulted in a superior response. The addition of an exogenous source of interleukin 1 proved necessary to obtain an alloreactive but not an antigen-specific T cell response, although its inclusion did enhance the magnitude of antigen-stimulated proliferation. These tumor cells should prove useful in studying the biochemical events that occur during antigen processing and the requirements for T cell triggering by processed antigen in association with Ia molecules.
Quantitative studies of in situ immune complex glomerulonephritis in the rat induced by planted, cationized antigen
Authors: Oite T , Batsford SR , Mihatsch MJ , Takamiya H , Vogt A
Published: June 2004

Cationized human IgG can bind to the rat glomerular basement membrane (GBM), act as planted antigen, and induce in situ immune complex formation accompanied by severe glomerulonephritis. Perfusion of highly cationized human IgG (isoelectric point {more than} 9.5) via the left renal artery resulted in preferential localization within the perfused kidney (up to 56 percent of dose injected); after intravenous administration, only 4 percent was bound to the kidneys. The planted antigen was localized along the glomerular capillary walls and was accessible for antibody administered intravenously 1 h after perfusion, when virtually no antigen remained in the circulation.

Persistence of cationized human IgG in the perfused kidney was markedly prolonged when complexed with antibody; one-half the cationized human IgG was still present after 12 d. There was a difference in the disappearance rates of antigen and antibody, as cationized human IgG was removed faster from the kidney than the antibody, the binding of which remained almost unchanged during the first week. Renal perfusion of a minimum of 20 μg of cationized human IgG, followed by intravenous injection of antibody, regularly induced severe glomerulonephritis with a proteinuria of at least 100 mg/24 h. The degree and the persistence of proteinuria induced depended on the dose of cationized human IgG perfused.

Experiments using radiolabeled antigen and antibody showed that after renal perfusion of 20 μg cationized human IgG, 11.1 μg was kidney bound at the time of antibody injection. At the onset of proteinuria, 4.0 μg of antigen and 31.9 μg of anti-human IgG antibody were present in the perfused kidney. Immunofluorescence revealed immune deposits consisting of cationized human IgG and rabbit IgG (anti-human IgG) along the GBM. The staining pattern was linear (confluent) during the first 2 d and became granular during the course of the disease. Electronmicroscopically, a prominent finding was the accumulation of dense deposits, mainly in the subepithelial space and beneath the slit pores.
Role of the H-2 complex in induction of T helper cells in vivo. III. Contribution of the I-E subregion to restriction sites recognized by I-A/E-restricted T cells.
Authors: Alpert B , Sprent J
Published: June 2004

Previous studies on negative selection of T cells to sheep erythrocytes in irradiated mice showed that CBA (I-Ak,I-Ek) (kk) T cells comprise two subgroups of cells restricted by I-A (A alpha-A beta) and I-A/E (E alpha-E beta) molecules. Selection of the I-A/E-restricted by I-A (A alpha-A beta) and I-A/E (E alpha-E beta) molecules. Selection of the I-A/E-restricted subset requires that the donor T cells and the selection host share both I-A (E beta) and I-E (E alpha) gene products; only the I-A-restricted cells undergo selection in B10.A(4R) (kb) mice. This paper demonstrates that negative selection of the I-A/E-restricted subgroup of CBA T cells can occur in F1 hybrids between B10.A(4R) and various Ia.7+ (E alpha+) I-E-incompatible strains; selection does not occur in hybrids between B10.A(4R) and Ia.7- (E alpha-) strains. These data suggest that, despite the fact that E alpha chains display detectable structural allelic variations, these chains are functionally nonpolymorphic. This conclusion applies to E alpha k,d,p,r,j chains. With F1 hybrids between B10.A(4R) and another Ia.7+ strain, B10.PL (H-2u), in contrast, only intermediate selection is observed. This finding is consistent with recent evidence that cell surface expression of E alpha-u-E beta dimers displays strong cis preference. In contrast to E alpha+ CBA T cells, E alpha- B10.A(4R) (kb) T cells undergo complete negative selection in hosts matched only in the I-A (and H-2K) subregion, i.e., B10.BR (kk) mice; no selection occurs in B10 (bb) mice. These data imply that Ia-restricted T cells in E alpha- strains are probably restricted solely by I-A molecules.
Antibody-independent complement activation by myelin via the classical complement pathway.
Authors: Cyong J C , Witkin S S , Rieger B , Barbarese E , Good R A , Day N K
Published: June 2004

Murine or rabbit whole brain homogenates were shown to activate human complement via the classical pathway by an antibody-independent reaction. This activity required Ca++ ions. Anticomplementary activity in fractionated murine brain was found to reside in the myelin fraction and in purified myelin. It was absent, however, both from highly purified myelin basic protein (MBP) and from the MBP-free residue. Because purified MBP is a monomer and this protein exists in brain tissue largely as a dimer, the ability of the cross-linked form of MBP to activate complement was investigated. MBP, dimerized with difluorodinitrobenzene, was highly anticomplementary. The murine brain, inactive when taken from the newborn mouse, was shown to first acquire the capacity to activate complement at 7 d after birth. This finding is consistent with the report that the synthesis of myelin protein has been shown to be initiated in murine brain 8 d after birth. Complement activation by MBP could play an important role in the pathological changes observed in neurological disorders.
Development of cytolytic T lymphocyte precursors in organ-cultured mouse embryonic thymus rudiments.
Authors: Ceredig R , Jenkinson E J , MacDonald H R , Owen J J
Published: June 2004

The appearance of immunologically competent cells in the organ-cultured mouse fetal thymic rudiment has been investigated. Fetal thymuses removed at 14 d of gestation and cultured for 7-21 d were assayed for their content of cytolytic T lymphocyte precursors (CTL-P) directed against H-2d alloantigens. Whereas CTL-P were undetectable within fetal thymus until 18-19 d of gestation, their frequency in the organ-cultured fetal thymus was similar to, or greater than that found in the normal adult thymus. This direct demonstration of the appearance of alloreactive CTL-P in a closed in vitro system should provide an accessible model for the investigation of interactions between developing T cells and the thymic microenvironment.
Infrequent normal B lymphocytes express features of B-chronic lymphocytic leukemia.
Authors: Caligaris-Cappio F , Gobbi M , Bofill M , Janossy G
Published: June 2004

An infrequent (2-3%) B lymphocyte subpopulation was found in the normal human tonsil and lymph nodes that shows the phenotypic characteristics of B-chronic lymphocytic leukemia (B-CLL) (rosette formation with mouse erythrocytes, weak expression of membrane Ig, staining for HLA-DR, and OKT1 or Leu-1 detecting a T cell-associated p65 antigen). Preliminary evidence suggests that at least a subpopulation of these cells is found, in small proportions, within the germinal centers. These cells were not observed in the human bone marrow. B-CLL may involve this peripheral B lymphocyte subset.
Synthesis of leukotriene C and other arachidonic acid metabolites by mouse pulmonary macrophages.
Authors: Rouzer C A , Scott W A , Hamill A L , Cohn Z A
Published: June 2004

Mouse resident pulmonary macrophages were subdivided into alveolar (PAM) and interstitial (PTM) populations on the basis of accessibility to pulmonary lavage, and zymosan-induced arachidonic acid (20:4) metabolism was examined in both populations labeled with [3H]20:4. Maximal phagocytic doses of unopsonized zymosan induced the specific release of 11% of phospholipid 20:4 by PTM and 4.6% by PAM. Direct fatty acid analysis of [3H]20:4-labeled PTM cultured in the presence or absence of zymosan indicated that the specific activity of the [3H]20:4 in cell phospholipid provided an accurate measure of 20:4 released by the cells, and could therefore be used to quantitate the synthesis of 20:4 metabolites by PTM in vitro. The single major 20:4 metabolite of PTM was the slow-reacting substance leukotriene C, which was synthesized in quantities of 3-4 pmol/microgram cell protein (280-370 pmol/10(6) cells), and comprised 20-25% of the released 20:4. PTM also synthesized prostaglandin E2, prostacyclin, thromboxane A2, and hydroxyeicosatetraenoic acids. In contrast, PAM produced leukotrienes D and E in addition to leukotriene C, prostaglandin E2, thromboxane A2, and hydroxyeicosatetraenoic acids. Prostacyclin formation by PAM was not observed. These studies define a set of experimental conditions for the study of 20:4 metabolism by pulmonary macrophages, and demonstrate that these cells are rich sources of LTC as well as other 20:4 oxygenated products.
T cell-derived B cell differentiation factor(s). Effect on the isotype switch of murine B cells.
Authors: Isakson P C , Puré E , Vitetta E S , Krammer P H
Published: June 2004

Culturing BALB/c B cells for 6 d at low cell density in the presence of lipopolysaccharide (LPS) results in the appearance of a small number of IgG plaque-forming cells (PFC). The addition of supernatants from concanavalin A (Con A)-induced alloreactive (AKR anti-B6) long-term T cell lines (PK 7.1.1a and 7.1.2) or a T cell hybridoma (FS7-6.18) to LPS-treated B cells resulted in a marked increase in IgG PFC (3--10-fold higher than in cultures treated with LPS alone. The number of induced IgG PFC was not affected by removing IgG-bearing cells on the fluorescence-activated cell sorter, indicating that T cell-derived B cell differentiation factor enhances isotype switching of sIgG- cells, rather than selecting and expanding pre-existing subpopulations of sIgG+ cells. We also investigated the subclass of IgG produced in the absence or presence of T cell factors and found that PK 7.1.1a, PK 7.1.2, and FS7-6.18 supernatants selectively increased IgG1 production. Several other T cell supernatants containing a variety of lymphokines had no effect, suggesting that PK 7.1.1a, PK 7.1.2, and FS7-6.18 lines produce factor(s) that can specifically enhance the recovery of IgG secreting cells in culture in the presence of LPS. These factors, which we have termed B cell differentiation factors, are different from interleukin 1, interleukin 2, T cell-replacing factor, colony-stimulating factor, macrophage-activating factor, and immune interferon. Our results suggest that soluble factors produced by T cell lines and hybridomas can markedly influence both the class and subclass of Ig produced by B cells.
The QA2 subregion controls the expression of two antigens recognized by H-2- unrestricted cytotoxic T cells
Authors: Forman J , Trial J , Tonkonogy S , Flaherty L
Published: June 2004

B6.KI mice were immunized with spleen cells from B6.K2, a Qa2-subregion congenic strain. Cytotoxic T cells were generated that recognize two target antigens controlled by this region.

One of the target antigens is Qa-2. This was demonstrated by the findings that pretreatment of target cells with monoclonal anti-Qa-2 antibody blocked lysis of target cells, and Qa-2 target antigens and serological determinants had a concordant distribution on a panel of B10.W (wild) mice. The gene controlling the Qa-2 target antigen is not polymorphic because B6.K2 and three strains of Qa-2(+) B10.W mice express the same antigens, as determined by a CTL cold target competition assay. Anti-Qa-2 CTL were H-2 unrestricted because effector cells lysed Qa-2(+) targets irrespective of their H-2 haplotype, including five B 10.W strains, and lysis was not inhibited by pretreating target cells with anti-H-2 sera. The Qa2 subregion does not act as a restricting locus for anti-minor-H antigen CTL.

A second target antigen was detected that was associated with the expression of the Qa-5 determinant. However, CTL activity could not be blocked by pretreating target cells with monoclonal anti-Qa-5. Therefore, the CTL target antigen may be expressed on a Qa-5(-) molecule. Although the Qa-5 associated CTL specificity is only detected on H-2D(b) strains, it is unlikely that CTL recognition is H-2 restricted because anti-H-2(b) sera has no effect in blocking this reactivity.

Qa-2 and H-2 class I antigens share a similar structure and serve as target antigens for unrestricted CTL. However, unlike class I H-2 genes, Qa-2 neither restricts antigen-specific CTL nor is polymorphie. Therefore, it is likely that Qa-2 and H-2 are derived from a common ancestral gene and have evolved to serve different functions.
Helper activity is required for the in vivo generation of cytotoxic T lymphocytes
Authors: Keene J-A , Forman J
Published: June 2004

B6.T1a(a) (Qa-1(a)) mice that are primed in vivo and restimulated in vitro with Qa-1 congenic spleen cells from B6 (Qa-1(b)) animals are unable to generate anti-Qa-1(b) cytotoxic T lymphocytes (CTL). This nonresponsive pattern was observed regardless of the route of immunization or the time of testing in vitro.

Although B6.T1a(a) mice are nonresponders to Qa-1(b) when presented on B6 cells, these mice can generate anti-Qa-1(b) CTL when primed in vivo with Qa-1 and H-Y alloantigens (females primed with B6 male cells) or Qa-1 and minor-H- alloantigens (primed with sex-matched A.BY cells). Therefore, the inability to generate anti-Qa-1(b) CTL is due to a lack of helper or accessory antigens on B6 immunizing cells obligatory during in vivo priming, rather than an absence of anti-Qa-1(b) CTL precursors (CTL-P). Demonstration that the additional determinants required during in vivo priming actually function as carrier or helper determinants was shown by the requirement for linked recognition of Qa-1 and the helper determinants (H-Y) in vivo, and the fact that H-Y was not present on susceptible target ceils. Animals primed in vivo with H-Y only could not generate anti-Qa-1 CTL activity when challenged in vitro with both Qa-1 and H-Y, indicating that recognition of the helper determinant causes in vivo priming of CTL-P rather than generating helper activity that might activate unprimed CTL-P in vitro.

Whereas unprimed peripheral CTL-P require the presence of both Qa-1 (CTL) and H-Y (helper) determinants for successful in vivo priming, helper determinants were not required in vitro because primed CTL-P from B6.T1a(a) mice could be driven to CTL in vitro using sex-matched B6 stimulator cells.

The generation of anti-Qa-1(b) CTL is under immune response (Ir) gene control because F(1) mice, obtained by crossing responder A/J with nonresponder B6.T1a(a) animals, generated CTL to the Qa-1(b) alloantigen when presented on B6 spleen cells. Progeny testing of backcross mice further demonstrated that the Ir gene(s) is linked to the H-2 complex.

These data indicate that an H-2-linked Ir gene controls the recognition of helper determinants required for CTL priming in vivo. These helper determinants can be distinguished from CTL determinants and both must be recognized together for successful priming of CTL-P.
Studies on the mechanism of bacterial resistance to complement-mediated killing. I. Terminal complement components are deposited and released from salmonella minnesota S218 without causing bacterial death
Authors: Joiner KA , Hammer CH , Brown EJ , Cole RJ , Frank MM
Published: June 2004

The mechanism of resistance of gram-negative bacteria to killing by complement was investigated. Complement consumption and uptake of purified, radiolabeled complement components on bacteria was studied using a serum- sensitive and a serum-resistant strain of Salmonella minnesota. Twice as many molecules of (125)I C3 were bound per colony-forming unit (CFU) of the smooth, serum-resistant S. minnesota S218 as were bound per CFU of the rough, serum-sensitive S. minnesota Re595 in 10 percent pooled normal human serum (PNHS), although 75-80 percent of C3 was consumed by both organisms. Hemolytic titrations documented total consumption of C9 by 5 min and more than 95 percent consumption of C5 and C7 by 15 min in the reaction with S218 with 10 percent PNHS. In contrast, negligible C5 depletion, 10 percent C7 consumption, and only a 26 percent decrease in C9 titer occurred with the serum-sensitive Re595. Binding of (125)I C5, (125)I C7, and (125)I C9 to S218 and Re595 was measured in 10 percent PNHS. A total of 6,600 molecules C5/CFU, 5,200 molecules C7/CFU, and 3,100 molecules C9/CFU bound to S218 after 5-10 min of incubation at 37 degrees C, but 50-70 percent of the C5, C7, and C9 bound to S218 was released from the organism during incubation at 37 degrees C for 60 min. Binding of 2,000 molecules C5/CFU, 1,900 molecules C7/CFU, and 9,000 molecules C9/CFU to Re595 was achieved by 20 min and was stable. The ratio of bound C9 molecules to bound C7 molecules, measured using (131)I C9 and (125)I C7, was constant for both organisms after 15 min and was 4.3:1 on Re595 and 0.65:1 on S218 in 10 percent PNHS. With addition of increasing amounts of purified, unlabeled (29 to 10 percent PNHS, there was no change in the C9:C7 ratio on Re595. However, with S218 there was a linear increase of the C9:C7 ratio, which approached the ratio on Re595. There was no (14)C release from S218 incubated in PNHS, nor was there evidence by electron microscopy of outer membrane damage to S218. Therefore, S. minnesota S218 is resistant to killing by PNHS, despite the fact that the organism consumes terminal complement components efficiently and that terminal components are deposited on the surface in significant amounts. The C5b-9 complex is released from the surface of S218 without causing lethal outer membrane damage.
Prostaglandin E inhibits the production of human interleukin 2.
Authors: Rappaport R S , Dodge G R
Published: June 2004

Prostaglandins of the E type specifically inhibited the production of interleukin 2 (IL-2) by normal human lymphocytes, whereas PG synthetase inhibitors such as indomethacin and fentiazac raised IL-2 production above normal levels. Removal of adherent cells from mononuclear cell populations also resulted in enhanced IL-2 production. The resultant nonadherent cell population lost sensitivity to the enhancement effect of PG synthetase inhibitors, suggesting that a PGE-producing adherent cell plays a major role in the regulation of IL-2.
Specificity studies on cytolytic T lymphocytes directed against murine leukemia virus-induced tumors. Analysis of monoclonal cytolytic T lymphocytes.
Authors: Plata F
Published: June 2004

The specificities of cloned cytolytic T lymphocytes (CTL) were studied for the analysis of CTL populations generated against murine leukemia viruses (MuLV) in H-2 congenic BALB/c (H-2d) and BALB.B (H-2b) mice. In particular, CTL generated in response to tumors induced by Gross MuLV and Friend MuLV were studied; these tumors expressed virus-induced antigens that do not cross-react and that can be distinguished from each other. The systematic study of 92 CTL clones clearly indicated that MuLV-immune CTL were highly heterogeneous with respect to both the intensities of target cell lysis that they mediated and to their specificity of recognition of MuLV-induced tumor target cells. Various categories of CTL clones were identified, ranging from CTL clones tht were tightly H-2 restricted and specific for the immunizing tumor to CTL clones that displayed no discernible patterns of specificity and that attacked a large number of different target cells. In addition, the surface markers of these cloned CTL were defined, and the best conditions for their prolonged maintenance in culture were determined. The present data indicate that future efforts in the definition of target antigens recognized by tumor-specific CTL should be performed with monoclonal lymphocytes.
Cyclophosphamide-facilitated adoptive immunotherapy of an established tumor depends on elimination of tumor-induced suppressor T cells.
Authors: North R J
Published: June 2004

On the basis of preceding studies showing that tumor-induced, T cell-mediated immunosuppression serves as an obstacle to adoptive immunotherapy of the Meth A fibrosarcoma, it was predicted that cyclophosphamide treatment of tumor bearers would remove this obstacle and allow passively transferred immune T cells to cause tumor regression. It was found that infusion of immune spleen cells alone had no effect on tumor growth, and cyclophosphamide alone caused a temporary halt in tumor progression. In contrast, combination therapy consisting of intravenous injection of 100 mg/kg of cyclophosphamide followed 1 h later by intravenous infusion of tumor-immune spleen cells caused small, as well as large tumors, to completely and permanently regress. Tumor regression caused by combination therapy was completely inhibited by intravenous infusion of splenic T cells from donors with established tumors, but not by spleen cells from normal donors. These suppressor T cells were eliminated from the spleen by treating the tumor-bearing donors with 100 mg/kg of cyclophosphamide. Immune T cells, in contrast, were resistant to this dose of cyclophosphamide. These results show that failure of intravenously-infused, tumor-sensitized T cells to cause regression of the Meth A fibrosarcoma growing in its syngeneic or semi-syngeneic host is caused by the presence of a tumor-induced population of cyclophosphamide-sensitive suppressor T cells.
Murine interstitial nephritis. I. Analysis of disease susceptibility and its relationship of pleiomorphic gene products defining both immune-response genes and a restrictive requirement for cytotoxic T cells at H-2K.
Authors: Neilson E G , Phillips S M
Published: June 2004

Anti-tubular basement membrance (alpha TBM) disease-producing interstitial nephritis in mice is not dependent on the generation of alpha TBM antibodies. Susceptibility seems to be defined by very private specificities in H-2K. These specificities are pleiomorphic, providing both immune-response genes and identity restrictions for cytotoxic effector functions expressed by a Thy-1.2+, Lyt-2,3+ T cell. These studies establish a role for T cells in the pathogenesis in interstitial nephritis as well as providing further evidence for the role of H-2K in the expression of an autoimmune disease.
Contribution of antigen-presenting cell major histocompatibility complex gene products to the specificity of antigen-induced T cell activation
Authors: Heber-Katz E , Schwartz RH , Matis LA , Hannum C , Fairwell T , Appella E , Hansburg D
Published: June 2004

Previous studies from our laboratory showed that B 10.A mice are high responders to pigeon cytochrome c fragment 81-104, whereas B 10.A(5R) mice are low responders. In the present studies, the C-terminal cyanogen bromide cleavage fragment and homologous synthetic peptides of tobacco horn worm moth cytochrome c were shown to be immunogenic in both B10.A and B10.A(5R) mice. These strains, however, showed different patterns of cross-reactivity when immune lymph node T cells were stimulated with cytochrome c fragments from other species. To examine the two patterns of responsiveness at a clonal level, cytochrome c fragment-specific T cell hybridomas were made and found to secrete interleukin 2 in response to antigen. The patterns of cross- reactivity of these B 10.A and B 10.A(5R) clones were similar to that seen in the whole lymph node population. Surprisingly, when these clones were tested for major histocompatibility complex (MHC)-restricted antigen recognition, they were all found to respond to antigen with both B10.A and B10.A(5R) antigen-presenting cells (APC). Furthermore, the cross-reactivity pattern appeared to be largely determined by the genotype of the APC, not the genotype of the T cell clone. That is, a given T cell clone displayed a different fine specificity when assayed with B10.A or B10.A(5R) APC. This observation indicates that the APC MHC gene product and antigen interact during the stimulation of the T cell response and that as a consequence the specificity of antigen-induced T cell activation is influenced by these MHC gene products.

(During the preparation of this manuscript it has come to our attention that results similar to our own, concerning the fine specificity of cytotoxic T cell clones, have been obtained by Dr. T. R. Hunig and Dr. M. J. Bevan, Massachusetts Institute of Technology, Boston, MA. T. R. Hunig and M. J. Bevan. 1981. Specificity of T-cell clones illustrates altered self hypothesis. Nature. 294:460.)
Evidence for the horizontal acquisition of murine AKR virogenes by recent horizontal infection of the germ line
Authors: O'Brien SJ , Moore JL , Martin MA , Womack JE
Published: June 2004

Several recent reports (8, 10, 11, 13) have established the biological and molecular genetic similarity between the endogenous AKV virus of strain AKR, and an N-ecotropic endogenous virus found in the genome of feral Japanese mice, Mus musculus molossinus. The similarities are so striking as to suggest a common origin of these viruses, which are present in some, but not all, inbred mouse strains. The virogenes of AKR mice may have been acquired by either: (a) common descent of AKR (and other AKV(+) strains) from a common ancestor of AKR and molossinus animals, or (b) horizontal germ line infection of the AKR strains by molossinus virus at 1;he strain's inception followed by fixation through inbreeding. The sexual descent model carries with it a prediction of relative consanguinity of the AKR strain and molossinus, whereas the horizontal infection model does not. We have examined the polymorphic allozyme (allelic isozyme) genotype of 51 nonvirus-related loci in 17 strains of mice including AKR, C58, BALB/c, Swiss, and molossinus. By comparing the composite allozyme genotype of different inbred and outbred mouse strains, the "genetic distance" statistic was derived. Genetic distance measures the degree of allelic substitution between populations and increases proportionately with the amount of time the populations have been reproductively isolated. The genetic distance computed between molossinus and AKR is large, nearly 5-10 times the distance between known related populations and strains (e.g., C57L vs. C57BL/6). Molossinus had a similarly large distance from AKV negative strains (Swiss, C57L) as it did from AKV- positive strains.

Cellular DNA sequences that flank the integrated AKV provirus were analyzed by restriction enzyme digestion of liver DNA from molossinus, AKR, and additional inbred strains that express ecotropic murine leukemia virus. The integration flanks of three AKR provirus sequences, Akv-1, Akv-2, and a third uncharacterized sequence, were not evident in molossinus cell DNA, which contained at least six different proviral integration fragments. These data effectively exclude the interpretation of consanguinity of AKR and molossinus and support the notion of acquisition of the endogenous virus in AKR by horizontal infection of the molossinus virus.
Cytotoxic T lymphocytes produce immune interferon in response to antigen or mitogen.
Authors: Klein J R , Raulet D H , Pasternack M S , Bevan M J
Published: June 2004

Interferon (IFN) was found to be secreted by cloned lines of murine cytotoxic T lymphocytes in response to mitogenic or antigen specific stimulation. The IFN produced was shown to be of the immune type based on its sensitivity to pH 2.0 and on the ability of an antiserum to immune IFN to neutralize the antiviral activity.
T lymphocyte-mediated suppression of myeloma function in vitro. IV. Generation of effector suppressor cells specific for myeloma idiotypes.
Authors: Abbas A K , Takaoki M , Greene M I
Published: June 2004

BALB/c mice immunized intravenously with syngeneic splenocytes, to which affinity-purified IgA produced by the MOPC 315 myeloma is covalently coupled, develop suppressor T cells (Ts1) that inhibit IgA secretion by MOPC 315 cells after 3-4 d of co-culture. Immunization with M315-coupled splenocytes subcutaneously, followed by administration of a soluble extract of Ts1 cells, leads to the generation of effector Ts that are also idiotype specific and inhibit myeloma function within 1 d. Moreover, effector Ts are Lyt-1-2+, whereas Ts1 are either Lyt-1+2+ or require Lyt-1+ and Lyt-2+ cells to mature into effector Ts in vitro. Such a protocol should be useful for analyzing the interactions that result in the maturation of Ts and in defining the mechanisms of action of Ts, whose effect can be measured on a homogeneous target population and that are specific for a well-characterized myeloma idiotype.