bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biased utilization of DHQ52 and JH4 gene segments in a human Ig transgenic minilocus is independent of antigenic selection.
Authors: Tuaillon N , Miller A B , Longberg N , Tucker P W , Capra J D 
Published: December 2022

Abstract
We have assessed the effect of antigenic selection on human Ig heavy chain D and JH gene segment utilization in mice that contain transgenes composed of 2 VH (psi VH3-105 and VH5-251), 10 D, 6 JH, C mu, and C gamma 1 human gene segments. Human heavy chains using the functional VH5-251 gene segment are expressed in the serum and on the surface of murine B cells. The second VH gene segment (psi VH3-105) is not expressed as a protein but is rearranged and transcribed into mRNA. We previously reported that the functional VH5-251 mu transcripts preferentially used the DHQ52 and JH4 gene segments similar to their use in the human repertoire. Here, we demonstrate that the nonfunctional (psi VH3-105) gene segment shows the same bias in D and JH gene segment utilization. Because transcripts using the pseudo-VH gene segment cannot be subjected to antigenic selection, we conclude that the restricted repertoire observed is Ag independent. Analysis of pseudo VH gene segment recombination products reveals no bias in D gene segment reading frame utilization. Finally, we demonstrate that in the human transgene coding sequence complementarities can affect the recombination site and that D inversion is common.
Characterization of the T cell determinants in the induction of autoimmune arthritis by bovine alpha 1(II)-CB11 in H-2q mice.
Authors: Brand D D , Myers L K , Terato K , Whittington K B , Stuart J M , Kang A H , Rosloniec E F 
Published: December 2022

Abstract
Collagen-induced arthritis (CIA) is an experimental autoimmune disease elicited in genetically susceptible strains of mice by immunization with heterologous type II collagen. This experimental disease is mediated by the immune response of both T and B cells, and susceptibility is restricted by the class II molecules of the MHC. To study the T cell determinants of bovine type II collagen (CII) that mediate the autoimmune response in H-2q mice, we have identified a cyanogen bromide fragment of bovine CII, CII(124-402), that induces arthritis in DBA/1 mice. Using an overlapping set of peptides to map the T cell response to CII(124-402), we have determined that the I-Aq-restricted T cell response to this collagen fragment is mediated by a single immunodominant antigenic determinant. Consequently, this determinant plays a central role in promoting the production of the collagen-specific Abs and the induction of CIA in H-2q mice. Characterization of this immunodominant determinant revealed that the core residues required for T cell stimulation consists of only eight amino acids and is located at amino acids 260 through 267 of bovine CII. The systematic analysis of the contribution of each of these amino acids, in conjunction with sequences of other peptides known to bind to I-Aq, have allowed us to propose a peptide binding motif for the collagen arthritis susceptibility allele, I-Aq.
Class I-restricted cytotoxic T lymphocytes are directly cytopathic for their target cells in vivo.
Authors: Ando K , Guidotti L G , Wirth S , Ishikawa T , Missale G , Moriyama T , Schreiber R D , Schlicht H J , Huang S N , Chisari F V 
Published: December 2022

Abstract
Although CD8-positive, class I-restricted CTL play a critical role in viral clearance and immunopathology in many model systems, they have not been shown to directly kill their target cells in vivo at the single cell level. Using a hepatitis B surface Ag transgenic mouse model of class I-restricted, CTL-mediated liver disease, we now demonstrate that CD8-positive, Ld-restricted hepatitis B surface Ag-specific CTL bind and kill their target cells in vivo by triggering them to undergo degenerative cytologic changes compatible with apoptosis. Unexpectedly, the data also indicate that the pathologic consequences of this direct, Ag-specific CTL effect are much less severe than the cytodestructive, Ag-nonspecific inflammatory response that they induce when they are activated by Ag recognition.
Heat-stable antigen is an important costimulatory molecule on epidermal Langerhans' cells.
Authors: Enk A H , Katz S I 
Published: December 2022

Abstract
Heat-stable antigen (HSA), expressed by activated B cells, has been described as a costimulatory molecule for CD4+ T cells. Because epidermal Langerhans cells (LC) are known to express HSA, we determined whether LC HSA also served as a costimulator of Th cells. We have confirmed that HSA is expressed by freshly prepared (fresh) and, to a lesser extent, short-term cultured (cultured) LC and we demonstrate that costimulatory effects of HSA are prominent on fresh and 1-day cultured LC, whereas 2- to 4-day cultured LC exhibit less HSA-costimulatory activity. The anti-HSA mAb 20C9 almost completely blocked the proliferative response of Th1 or lymph node T cells induced by fresh or cultured LC. 20C9 also specifically inhibited LC-dependent IL-2 production by Th1 cells. The inhibitory effect of 20C9 was not observed when Th2 cells were substituted for Th1 cells or peripheral lymph node T cells. Furthermore, Th1 cells rescued from cocultures of T cells and 20C9-treated, Ag-pulsed LC, (but not from control-treated cocultures) were anergic to restimulation with untreated Ag-pulsed LC. These data suggest that LC HSA is an important costimulatory molecule in Th1 cell-dependent cutaneous immune reactions.
CD28-mediated costimulation is necessary for optimal proliferation of murine NK cells.
Authors: Nandi D , Gross J A , Allison J P 
Published: December 2022

Abstract
CD28, a cell surface molecule expressed on all murine T cells, plays a critical role in T cell activation. We show here that NK-1.1+ cells, a subpopulation of SCID splenocytes, and IL-2-activated NK cells express CD28, although at lower levels than alpha beta T cells. Optimal proliferation of highly purified asialo GM1+ NK cells from the SCID spleen was observed in response to stimulation with IL-2 and PMA, together with anti-CD28 or L-B7+ cells. Thus, in addition to IL-2, murine NK cells require CD28-mediated costimulatory signals for optimal proliferation. IL-2-activated NK cells produced enhanced levels of IFN-gamma and TNF in response to stimulation with anti-CD28 and PMA. On the other hand, we were unable to demonstrate that CD28 signaling had any effect on NK-mediated cytotoxicity. We conclude that the CD28 costimulatory pathway is functional in NK cells and plays an important role in their proliferation and cytokine production.
Assessment of CD4 expression by early T precursor cells and by dendritic cells in the human thymus.
Authors: Sotzik F , Rosenberg Y , Boyd A W , Honeyman M , Metcalf D , Scollay R , Wu L , Shortman K 
Published: December 2022

Abstract
The adult mouse thymus contains a minute population of early lymphoid precursor cells that express moderate levels of CD4. We searched for a corresponding population of early T precursors in the infant human thymus, by first depleting the majority of more mature thymocytes, then using immunofluorescence and flow cytometry to analyze cells bearing a range of early T lineage markers. No discrete population of early T precursors expressing CD4 was observed, in contrast to the murine thymus. Most putative very early human thymocytes were CD4-8-3-1-2lo44+34+7hi class I MHChi class II MHC-. However, a distinct population of human thymic dendritic cells expressing high levels of CD4 was isolated. These were CD4hi8-3-1-2-44+34-7- class I MHChi class II MHChi, and lacked markers of B cells, NK cells, or myeloid cells. They were large cells that exhibited dendritic morphology after brief periods of culture, and they were efficient stimulators of allogeneic T cells. The biologic implications of CD4 expression by thymic dendritic cells are discussed.
Switch circles from IL-4-directed epsilon class switching from human B lymphocytes. Evidence for direct, sequential, and multiple step sequential switch from mu to epsilon Ig heavy chain gene.
Authors: Zhang K , Mills F C , Saxon A 
Published: December 2022

Abstract
Ig isotype switch via deletional recombination is accompanied by excision of the intervening DNA between the two switch regions. The excised DNA is looped out as extrachromosomal circular DNA or switch circle. Such switch circles have been isolated and characterized in mice. We investigated deletional recombination in human B cells undergoing Ig isotype switching to demonstrate whether switch circles are also excised, and to thereby gain insight into the processes involved in human isotype switching. We characterized the deleted switch circular DNA from IL-4 directed mu to epsilon switching in polyclonal human B lymphocytes. By using two sets of specially designed PCR primers, we amplified switch circle fragments representing switch circles resulting from mu to epsilon direct switching and mu-gamma-epsilon sequential switching. The PCR-amplified products were subcloned by a TA cloning strategy and resulting clones were screened by hybridization with a 5'S epsilon probe. Sequence analysis of the positive clones revealed that all clones representing mu to epsilon direct switching indeed had 5'S epsilon directly joined to 3' S mu. Most clones representing mu-gamma-epsilon sequential switching showed 5'S epsilon joined to 3' S gamma as expected. However, two clones contained S mu and S alpha 1 sequences interposed between 5'S epsilon and 3'S gamma, respectively. These data demonstrate that switch circles are excised during human B cell isotype switching, and that IL-4 directed epsilon class switching is accomplished by 1) direct mu to epsilon switching, 2) sequential mu-gamma-epsilon switching, and 3) double sequential mu-alpha-gamma-epsilon switching.
Biochemical and biologic characterization of murine monocyte chemoattractant protein-1. Identification of two functional domains.
Authors: Ernst C A , Zhang Y J , Hancock P R , Rutledge B J , Corless C L , Rollins B J 
Published: December 2022

Abstract
Monocyte chemoattractant protein-1 (MCP-1) is a member of the chemokine-beta (or C-C) family of cytokines. Murine MCP-1, first identified as the JE gene, differs from human MCP-1 in molecular size and extent of glycosylation. We have used Chinese hamster ovary cells to express recombinant murine MCP-1 and find that its predominant form is a microheterogeneous protein of M(r) approximately 25,000. Most of MCP-1's microheterogeneity is due to variable amounts of sialic acid that are terminally attached to a constant number of O-linked oligosaccharide chains per molecule. This carbohydrate, along with a small amount of N-linked carbohydrate, accounts for 50% of the apparent molecular size of murine MCP-1 and is not required for in vitro monocyte chemoattractant activity. Mutational analysis shows that most of the carbohydrate is added to a 49-amino acid C-terminal domain that is not present in human MCP-1 and is not required for in vitro biologic activity, suggesting that murine MCP-1 consists of an N-terminal domain containing monocyte chemoattractant activity and a heavily glycosylated C-terminal domain of as yet unknown function. MCP-1 produced in COS cells contains a small amount of sulfate, but Chinese hamster ovary-produced MCP-1 does not. The absence of sulfate does not alter MCP-1's in vitro chemoattractant properties. In vitro, highly purified murine MCP-1 attracts monocytes, but not neutrophils, with a specific activity similar to human MCP-1 (EC50 approximately 0.5 nM). Equilibrium binding experiments with human monocytes reveal the presence of approximately 3000 binding sites per cell with a Kd of 0.77 nM. In vivo, injection of up to 1 micrograms murine MCP-1 in a variety of murine strains induces the appearance of a sparse mixed inflammatory infiltrate. The disparity between MCP-1's in vitro and in vivo effects suggests that other factors may be required to elicit a full-blown monocyte chemotactic response to MCP-1 in vivo.
TNF induces internalization of the p60 receptor and shedding of the p80 receptor.
Authors: Higuchi M , Aggarwal B B 
Published: December 2022

Abstract
As is true for other peptide hormones, TNF causes the down-modulation of its own receptor. The process by which down-regulation occurs and the particular role of each of two recently identified receptors, however, are not understood. In this report we used Abs specific to p60 and p80 TNFR types to examine the ligand-induced down-regulation in histiocytic cell line U-937. These cells express both types of TNFRs, but the amount of p80 is two to three times greater than that of the p60 receptor. Treatment of U-937 cells with the ligand led to maximum down-modulation of TNFR within 30 min, and this decrease was found to be a result of receptor number and not affinity. When examined for the receptor type, approximately 90% of the p60 receptor and 35% of the p80 receptor was down-regulated by the cytokine. Rapid internalization of TNF in U-937 cells is mediated through p60, because this process was inhibited only by anti-p60 Ab and was also inhibited in cells (PMA-pretreated) that primarily express the p80 receptor. In contrast to p60, we observed that the ligand-induced shedding of the p80 receptor into the medium results in the down-regulation. Interestingly, however, the signal for shedding of the p80 receptor appears to be mediated through the p60 receptor, because anti-p60 Ab inhibited the shedding. Overall, our results provide evidence that ligand-induced down-modulation of TNFR is a result of the internalization of p60 and of the shedding of the p80 receptor and that the signaling for both is mediated through the p60 receptor.
In vivo or in vitro anti-CD3 epsilon chain monoclonal antibody therapy for the prevention of lethal murine graft-versus-host disease across the major histocompatibility barrier in mice.
Authors: Blazar B R , Taylor P A , Vallera D A 
Published: December 2022

Abstract
We explored the use of a single in vivo dose of an anti-CD3 epsilon mAb for graft-vs-host disease (GVHD) prevention in mice. Anti-CD3 epsilon (145-2C11) given on the day of bone marrow (BM) transplant was highly effective in preventing GVHD in a dose-dependent manner. However, mice experienced acute toxicity as measured by early post-BM transplantation mortality, severe weight loss, and cachexia, which is likely due to T cell-dependent lymphokine production. Donor T cells were partly responsible because toxicity still occurred in mice injected with an allelic specific anti-CD3 epsilon mAb that only reacted with the donor strain. Toxicity was also dependent on the number of radioresistant host T cells present at the time of transplant, because toxicity still occurred when recipients were depleted of mature T cells in vivo with anti-CD4+ anti-CD8 mAbs, and were given T cell-depleted BM from SCID mice. Toxicity was eliminated by treating BM with anti-CD3 epsilon mAb in vitro before BM transplant instead of administering the mAb in vivo. However, GVHD protection was not complete. Direct comparison of the in vivo and in vitro approaches revealed that the in vivo administration of anti-CD3 epsilon mAb was more effective for GVHD protection and that a combination of the approaches was not beneficial. Flow cytometry studies were performed to assess the degree of CD3 epsilon chain modulation and T cell depletion obtained with in vitro vs in vivo anti-CD3 epsilon chain mAb. In mice given syngeneic BM transplants to avoid the confounding effects of GVHD, we found that in vivo anti-CD3 epsilon mAb administration induced a more prolonged period of CD3 epsilon chain modulation and/or T cell depletion than either the in vitro approach or a third approach that involved anti-CD3 epsilon F(ab')2 fragments administered in vivo. These data indicate that targeting the Ag-specific TCR, especially in such a way as to avoid toxicity associated with T cell activation, may provide an important key for developing future GVHD therapies.
Aged T cells are hyporesponsive to costimulation mediated by CD28.
Authors: Engwerda C R , Handwerger B S , Fox B S 
Published: December 2022

Abstract
The ability of T cells to proliferate in response to a number of stimuli is impaired in healthy, aged individuals. T cells from young (2 to 4 mo) and aged (20 to 26 mo) mice were stimulated with immobilized anti-CD3 epsilon-chain mAb and soluble anti-CD28 mAb. T cells from young and aged mice proliferated comparably in response to anti-CD3 epsilon mAb alone. However, aged T cells were significantly less responsive to costimulation by anti-CD28 mAb. This decreased response of aged T cells was seen at all dosages tested of anti-CD3 epsilon and anti-CD28 mAbs and in the presence and absence of APC. Similar results were observed when costimulation was provided by B7-transfected L cell fibroblasts. T cells from young and aged mice had comparable expression of CD28 by flow cytometry, both before and after stimulation. The defect in response to CD28 was seen both in CD4+ and CD8+ T cells and in CD44lo (naive) and CD44hi (memory) T cells. The impaired response to costimulation mediated by CD28 on T cells from aged mice may be an important factor in reduced T cell responses associated with aging.
Enkephalin-containing peptides processed from proenkephalin significantly enhance the antibody-forming cell responses to antigens.
Authors: Hiddinga H J , Isaak D D , Lewis R V 
Published: December 2022

Abstract
Highly conserved enkephalin containing peptides (ECPs) are selectively processed from proenkephalin, which is synthesized in both the neuroendocrine and immune systems. The reported regulatory effects within the central nervous system and the biologic release patterns from both activated lymphocytes and stimulated adrenal chromaffin cells suggest the ECPs may act as regulatory factors of the immune system. We tested the effects of three of the ECPs, Peptides F, E, and B, on the in vitro Ab-forming cell (AFC) response murine splenocytes to antigenic challenge. In contrast to the immunosuppressive effects of the pentapeptide enkephalins, physiologic concentrations of the ECPs significantly enhanced the AFC response to both T cell-dependent and T cell-independent Ags. The effects are not sensitive to competition by the opiate receptor antagonist, naloxone, suggesting cell surface interactions that do not involve classical opiate receptors. These studies provide evidence that the effects are mediated through T cells rather than B cells. Peptide F-treated splenocytes also showed a significant enhancement of the AFC response to suboptimal Ag concentrations, suggesting a mechanism of action in which the ECPs may act to lower the threshold of activation of the effector cell. These results suggest that the ECPs are physiologically important modifiers of the humoral immune response. Given their release patterns and demonstrated action on the in vitro immune response, the proenkephalin-derived ECPs have the potential to be involved in both paracrine and autocrine regulatory networks within the immune system and as a positive immunoregulatory effect from the neuroendocrine system.
Induction of B cell and T cell tolerance in vivo by anti-CD23 mAb.
Authors: Morris S C , Lees A , Holmes J M , Jeffries R D , Finkelman F D 
Published: December 2022

Abstract
T cell tolerance can be induced by B cell presentation of Ags to naive T cells. To further characterize this mechanism of T cell tolerance induction, we have investigated the effects of injecting mice with an intact rat IgG2a Ab, which binds to the B cell low-affinity Fc epsilon receptor (CD23), on the responsiveness of B cells and T cells to rat IgG2a. Our observations indicate that 1) intravenous, subcutaneous, or intraperitoneal injection of this Ab induces antigen-specific B cell and T cell tolerance; 2) both forms of tolerance are induced more completely by injection of rat IgG2a anti-CD23 mAb than by injection of an equal dose of a control rat IgG2a Ig; and 3) reduced responsiveness to Ag is seen as early as 1 to 3 days after anti-CD23 mAb injection and reaches maximum levels by 7 days after injection. Although tolerance induced by the injection of soluble proteins has been reported to be characterized by reduced production of IL-2 and IFN-gamma, but normal production of IL-4, injection of mice with rat IgG2a anti-mouse CD23 mAb greatly decreases the IL-4 response to a rat IgG2a immunogen that normally induces a large IL-4 response.
Human primary immune response in SCID mice engrafted with human peripheral blood lymphocytes.
Authors: Sandhu J , Shpitz B , Gallinger S , Hozumi N 
Published: December 2022

Abstract
Severe combined immune deficient (SCID) mice were engrafted with human peripheral blood lymphocytes (Hu-PBLs) after treatment with anti-asialo GM-1 antiserum and radiation. This pretreatment facilitates high level of Hu-PBL engraftment in the SCID mice spleen. The next day, the Hu-PBL-SCID mice were immunized with either keyhole limpet hemocyanin (KLH), or carbohydrate Ag STn (AcNeu-alpha 2-alpha 6-Gal NAc-0) conjugated to KLH or protein of circumsporozoite malaria parasite (CSP), in a mixture of complete and incomplete Freund's adjuvant (1:10 v/v). The mice were bled 14 to 16 days after immunization, and the sera analyzed for STn-, KLH-, and CSP-specific human IgG and IgM Abs. The results showed that the immunized animals had a significantly higher titer of Ag-specific human IgG and IgM Abs compared to the control Hu-PBL-SCID mice. No significant Ab cross-reactions were detected between sera from KLH-, STn-, and CSP-vaccinated Hu-PBL-SCID mice. Depletion of either human CD4+ or CD8+ cells, in Hu-PBL-SCID mice, showed that CD4+ cells were essential for the primary immune response, but depletion of CD8+ cells had no influence on the titer of Ag-specific human IgG and IgM Abs.
Human CD45RC specificity. A novel marker for T cells at different maturation and activation stages.
Authors: Zapata J M , Pulido R , Acevedo A , Sánchez-Madrid F , de Landázuri M O 
Published: December 2022

Abstract
The different isoforms of CD45 seem to play an important role in thymocyte maturation and T cell activation and function. To investigate the particular contribution of CD45-exon C (exon 6) to human T cell development, we first investigated the expression of the CD45-exon C isoforms on different human lymphoid cell populations. A wide panel of mAbs against the different isoforms of CD45 was generated by immunizing mice with purified human CD45. Two of these mAbs (RP1/12 and RP2/19) selectively recognized mouse 300-19 pre-B cells that had been transfected with CD45 cDNA that contained exon C, suggesting that epitopes recognized by these mAbs are dependent on the expression of exon C. Immunofluorescence analysis of PBLs showed that CD45RC is expressed at high levels on B, NK, and CD8+ T cells, although a subset of CD4+ T cells was found to be negative. Activation of PBMCs and purified NK cells resulted in down-regulation of CD45RC, which took place in a coordinate manner involving both down-regulation of the expression of CD45RA and CD45RB and up-regulation of CD45R0. Two-color immunofluorescence analyses showed that thymocytes expressing CD45RC were CD1-to lo, CD3hi and HLA class Ihi, typical markers of mature thymocytes. Accordingly, immunohistochemical analysis of a normal thymus showed that whereas the anti-CD45RA mAb stained only a subset of medullary thymocytes, the anti-CD45RC mAb stained the majority of medullary thymocytes. Thymocytes that bear CD45RA also express CD45RC, but do not express CD45RO; a subset of CD45 RA- RO+ thymocytes was also detected. Immunoprecipitation of CD45 molecules from both PBMC and thymocyte cell lysates with mAbs against the different specificities of this molecule revealed that the RC determinants are found on CD45 polypeptides of 220 and 205 kDa that also bear RB or both RB and RA determinants, respectively. Together these results support both the existence of a tight regulation of the expression of CD45 specificities during lymphocyte activation and thymocyte maturation and also that CD45RC is selectively expressed by mature medullary thymocytes during T cell ontogeny.