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J F Kearney

Publications and source records attributed to J F Kearney.

At least 55 records · Page 3Linked to original sources
PubMed1995

T cell activation through Thy-1 is associated with the expression of a surface protein (p100) on a subset of CD4 cells.

Thy-1 molecules, which lack a transmembrane domain, can nonetheless induce T cell activation; it has thus been suggested that a separate transmembrane molecule associated with Thy-1 is required for signal transduction. We have previously characterized a transmembrane protein with an Mr of 100,000 (p100), which is non-covalently bound to two glycosyl-phosphatidylinositol (GPI)-linked molecules, Thy-1 and ThB. p100 is selectively expressed on the T cell surface and divides peripheral CD4 cells into two subpopulations. This differential expression on CD4 cells allowed us to investigate the role of p100 in signal transduction through Thy-1 molecules. Here we report that only p100+ CD4 cells proliferate and release cytokines in response to cross-linkage of Thy-1, although both p100+ and p100- CD4 cells strongly express Thy-1 on their surfaces. Control stimulation by anti-CD3 antibodies or concanavalin A induces identical thymidine uptake by the two CD4 cell populations. Interestingly, these two populations of CD4 cells had different cytokine release profiles after activation through CD3: only p100+ CD4 cells released high amounts of IL-2 and IFN-gamma, whereas both populations released IL-4. p100 expression correlates with the induction of homotypic aggregation of T cells after Thy-1 triggering. p100 is associated with kinase activity (fyn and lck), and phosphorylated proteins of 90, 59, 57 and 33 kDa co-precipitate with Thy-1 only in p100+ CD4 cells. Altogether, these data suggest that p100 is involved in signal transduction through Thy-1. p100 expression by activated CD4 cells in vivo may be relevant to the proposed function of Thy-1 as an accessory signaling molecule in cell activation.

Animals↗
PubMed1995

Sequence analysis and antigen binding characteristics of Ig SCID Ig+ mice.

SCID mice as they age may develop a limited number of functional B and T cell clones. VH and VL gene sequences of hybridoma antibodies derived from the spleens of five adult SCID Ig+ mice revealed nine clonally unrelated, i.e. derived from different precursor lymphocytes, groups of Ig. Of these, four used the VH7183 family, one Q52, three J558 and one VH3609. VH7183 was seen in excess over J558 despite a 5-fold larger number of J558 family members in the mouse genome. Preferential use of D proximal VH genes along with reduced N region addition in the heavy chain VDJ joins of these antibodies suggest derivation from a population of lymphocytes with characteristics of the perinatal repertoire. All of the hybridomas produced kappa light chains of several different VL family groups. Sequences of 23 VH and 22 VL genes of hybridomas derived from one mouse (no. 45) showed that they were all clonally related, differing only in somatic mutations. Autoreactivity of these antibodies to cellular antigens [including (U1)RNP-specific A protein and SmB] was analyzed, and shown to correlate with the geneology and specific mutations within members of the clone. The geneological tree derived from sequence data permitted a study of the microevolution of a clone of B cells and showed that as it developed there was a tendency toward increased strength of self-reactive binding as well as alterations in specificity toward these autoantigens. Analysis of replacement:silent mutation ratios within members of this clone reflected limited affinity maturation in mouse 45 and none for another mouse, no. 58. These data are consistent with the progressive differentiation of B cells in an immunodeficient state in the absence of clonal competition with B cells of similar antigen specificities as they populate the spleen.

Amino Acid Sequence↗
PubMed1994

Lymphopoiesis today.

Max Cooper has made research contributions that cover phylogenetic and ontogenic aspects of lymphopoiesis and immunodeficiency diseases, and has used molecular approaches to understand lymphocyte development and function. A large gathering of international colleagues met at a recent symposium to celebrate the occasion of his 60th birthday.

Animals↗
PubMed1994

Immunofluorescence analysis of B-1 cell ontogeny in the mouse.

In order to further understand the developmental aspects of B-1 cells, we characterized the ontogeny of this B cell population in the spleen and peritoneal cavity of BALB/c mice. Although there are B-1 cells in the spleen within the first 1-3 weeks after birth, they do not at any stage represent the majority of splenic B cells. Splenic B-1 cells reach peak levels at approximately 9 days after birth. The mesenteric lining that covers the small intestine of 7-day-old mice contains a population of IgM+ B cells, while at the same age, there are few lymphoid cells in the peritoneal cavity. Between 7 and 8 days after birth there is an influx of B cells into the peritoneal cavity. At 8 days, the first detectable peritoneal B cells appear to be of the B-1 type based on expression of IL-5 receptor and CD5. However, these peritoneal B-1 cells do not express Mac-1. This antigen is not expressed by the majority of peritoneal B-1 cells until 3 weeks. This study indicates that the majority of early splenic B cells are not B-1 cells and it suggests that the mesenteric tissues surrounding the gut contain B lymphocytes which traffic into the peritoneal cavity where they then reside.

Aging↗
PubMed1994

Effects of IgM allotype suppression on serum IgM levels, B-1 and B-2 cells, and antibody responses in allotype heterozygous F1 mice.

IgM allotype heterozygous F1 mice were independently suppressed for Igh6a or Igh6b to evaluate the contribution of B-1 and B-2 cells to natural serum IgM levels and Ab responses. B-2 B cells expressing IgM of the suppressed allotype were evident in the spleens of suppressed mice 4 to 6 weeks after cessation of the suppression regimen, whereas B-1 B cells of the suppressed allotype were undetectable for up to 9 months. Although serum IgM of the suppressed allotype was initially depleted in mice suppressed for either allotype, by 7 months of age, there were detectable levels of IgM of the suppressed allotype in the serum; however, the levels were significantly below that found in nonsuppressed mice. When mice were immunized with either the T-independent or T-dependent form of phosphorylcholine, those suppressed for either allotype, and consequently depleted of B-1 B cells of that allotype, did not respond with phosphorylcholine-specific IgM of the suppressed allotype. In contrast, when mice were immunized with alpha 1-3 dextran, the Igh6a allotype-suppressed mice were able to produce dextran-specific IgM of that allotype. These results show that allotype-bearing B-1 cells of both allotypes can be effectively suppressed by this suppression protocol and this produces long-lasting effects on B-1 cell levels and serum IgM of the suppressed allotype. These observations reflect the derivation of the majority of B-1 cells from fetal-neonatal precursors, which cannot be replaced by newly emerging B-2 cells of adult origin. Their ablation by antibody treatment results in permanent alterations to the adult B-cell repertoire.

Alleles↗
PubMed1993

CD5+ B-cell networks.

The relationship between precursors for B1 and B2 cells remains controversial. On the basis of recent experimental results, it is highly probable that B1 cells can be generated from the same sources as B2 cells. However, the precursor cell types involved, the microenvironment and the age of donor and recipient may all determine whether B1 cells are generated under the variety of experimental conditions that have been described in the literature. Definition of these influences will be important in understanding the role of B1 cells in autoimmune disease. Further differences in antigen responsiveness, localization and signaling between B1 and B2 cells will also be informative with respect to their roles in antibody production.

Animals↗
PubMed1993

Normal B lymphocyte differentiation.

Normal differentiation of B lineage cells has been the subject of intensive investigation over the past three decades. Current models of this process in humans are melded from the results of studies in a variety of organisms, including humans, mice and birds. Several recent developments have significantly reshaped and refined these models. The technique of homologous recombination in embryonic stem cells has allowed the production of mice with selectively disrupted genes that are important for B cell development in mice. At the same time, functional studies of human B cell differentiation, together with analysis of naturally occurring mutations that disrupt this process, have progressed rapidly. This has provided insight into the pathogenesis of lymphoproliferative and immunodeficiency diseases as well as a clearer view of normal developmental events. In this chapter we have reviewed human B cell differentiation with particular emphasis on newly emerging concepts. We also discussed CD5, a pan-T cell antigen that is expressed in low levels on a subpopulation of B cells implicated in the pathogenesis of chronic lymphocytic leukaemia (CLL). Finally, we discussed the issue of restricted variable region gene usage during B cell ontogeny and in CLL.

Animals↗
PubMed1992

The fetal omentum in mice and humans. A site enriched for precursors of CD5 B cells early in development.

From these studies the fetal omentum appears to be an important site of B-cell generation in humans and a source of CD5 B cells in mice. We have analyzed the fetal omentum in other species and have found that B-cell development as determined by the presence of cytoplasmic IgM+ pre-B cells is also detected in the fetal rabbit omentum. We do not know if there is bias towards the production of CD5 B cells in this species; however, these preliminary results demonstrate that this site may be conserved throughout evolution in mammals as a site of B-cell generation. Because the fetal liver is also a source of precursors that can reconstitute this B-cell subset, what is the relationship between omentum and liver during the development of Ly-1 B cells? The most obvious relationship between these two sites is that cells simply migrate from one location to the other; that is, precursor cells may migrate from the fetal liver into the fetal omentum and in this milieu give rise to exclusively Ly-1+ B cells or the sister population. Alternatively, precursors of Ly-1 B cells may arise in the omentum and migrate to the liver. This is demonstrated graphically in the diagram (Fig. 6a) of a transverse section through an 8-week human fetus. In this paper, however, we suggest a model for the development of Ly-1+ B cells from the omentum and liver in which Ly-1 B cells arise from distinct precursors located in situ in the mesodermally derived omentum and mesothelial-derived liver capsule. The omentum primordia forms as the back to back fusion of the mesodermally derived lining of the peritoneal cavity, and this lining surrounds the developing gut when the liver begins to develop as an outgrowth of the intestinal primordia at approximately 3.5 weeks gestation; the outer covering or capsule of the liver is derived from the same tissue of origin as the omentum. Figure 6B is a diagram of a section through the same plane as Figure 6A but the body wall has been omitted. We propose that the Ly-1+ B cells arise in situ in the omentum and lining of the liver as indicated in Figure 6B. That Ly-1+ B cells arise from distinct precursors has been suggested by others, but ours is the first evidence for a developmental site that apparently contains B-cell progenitors for this B-cell subset.

Animals↗
PubMed1992

Idiotypic regulation of development of the B-cell repertoire.

The mouse B-cell repertoire develops from a restricted set to an extremely diverse set of specificities. Establishment of some of the B-cell clones that constitute the adult repertoire is facilitated and guided by idiotype-directed interactions among complementary sets of B cells early during ontogeny. Through in vivo experiments described here and reported elsewhere, we have shown that the program of B-cell development involving idiotypic interactions is obligatory in the development of certain B cells that provide immunity against bacterial infections. Furthermore, this program of B-cell development is facilitated in newborn mice and not in adult mice that have been transplanted with progenitor cells from adult bone marrow. Thus the idiotype-directed selection of the adult B-cell repertoire appears to be limited to fetal-neonatal stages of development.

Aging↗
PubMed1992

The human fetal omentum: a site of B cell generation.

The fetal mouse omentum has been shown to be a source of precursors that exclusively reconstitutes Ly1+ B cells and the closely related Ly1- sister population, but not conventional B cells or T cells. We have extended these studies to compare B cell development in the human fetal omentum, liver, and spleen, and to demonstrate that the pro/pre-B cell compartment (CD24+, sIgM-) is detected in the omentum and liver but not spleen as early as 8 wk of gestation. From 8 to 12 wk of gestation, the proportions of IgM+ cells that were pre-B cells (cIgM+/sIgM-) in the omentum and liver were 53 +/- 15% and 45 +/- 13%, respectively, and IgM+ cells were not detectable in the spleen. After 12 wk, the percentage of pre-B cells was unchanged in the fetal liver (41 +/- 10%) but decreased significantly in the omentum (25 +/- 14%); pre-B cells were now detected in the spleen but at much lower percentages (2 +/- 3%) than either the omentum or liver. The nuclear enzyme, Tdt, was detected in approximately 25% of the CD24+ cells in the omentum and liver during the 8-12-wk time period, however, Tdt+ cells were not detected in the spleen. Approximately 40% of the mature B cells found in the omentum and spleen were CD5+ compared with only 20% in the liver. These results demonstrate that the fetal omentum, like the fetal liver and bone marrow, is a primary site of B cell development.

Antibodies, Monoclonal↗
PubMed1992

Identification of a surface protein (p100) associated with two glycosyl-phosphatidylinositol-linked molecules (Thy-1 and ThB) by natural anti-lymphocyte autoantibodies.

Our previous study of natural autoantibodies showed that anti-lymphocyte antibodies are frequently produced by perinatal B cells from normal strains of mice. One-third of these monoclonal antibodies (mAb) recognized similar epitopes on the surface of thymocytes. In the present report, we have characterized the molecule recognized by three of these mAb (D10, G7, 22). These mAb identified a 100-kDa protein (p100) on the surface of thymocytes. This protein resolved into 70-kDa polypeptide chains under reducing conditions. Inhibition experiments as well as antibody immunoprecipitations in the presence of mild detergents revealed non-covalent association of the p100 with Thy-1 and ThB. A similar multimolecular complex was identified following chemical cross-linking of thymocyte surface proteins. Analysis of several Thy-1-defective mutant cells lines, and thymocytes treated with phosphatidylinositol-specific phospholipase C (PI-PLC) showed that the expression of p100 was strongly influenced by Thy-1 molecule. The p100 was resistant to PI-PLC treatment and was not released into the supernatant as was the case for Thy-1 and ThB molecules. These data lead us to propose that the p100 is a transmembrane protein, the expression of which in the plasma membrane is dependent on the association or presence of Thy-1 molecule.

Animals↗
PubMed1992

Characterization, specificity, and IgV gene usage of anti-lymphocyte monoclonal antibodies from perinatal mice.

Previous studies have shown that CD5+ B cells predominate during development of the immune system and frequently secrete self-reactive antibodies, some of which appear to influence the development of the adult B cell repertoire. In addition, we now show that a high frequency of perinatally derived antibodies react with lymphocytes. Hybridomas derived from perinatal liver and splenic B cells and from spleens of adult BALB/c and C57BL/6 mice were screened by immunofluorescence on thymocytes. Anti-lymphocyte antibodies, all of the IgM isotype, were detected at a high frequency from perinatal fusions, but none were obtained from adult mice. These anti-lymphocyte mAbs were heterogeneous because they stained different subsets of peripheral T and B lymphocytes. Although the antigens recognized by these mAbs were heterogeneous with respect to their sensitivity to a variety of enzymes, 13 of the 19 mAbs recognized epitopes which were modulated by phosphatidylinositol-phospholipase C treatment. Inhibition experiments suggested that six of these 13 mAbs shared the same molecular specificity, and that they recognized the same T cell subset (62% of CD4+ and 98% of CD8+ cells). Furthermore, three of these mAbs immunoprecipitated the same 100 kDa protein from thymocytes (70 kDa in reducing conditions). The related molecular specificity of some anti-lymphocyte mAbs was also reflected by their restricted V gene usage. Three of the five mAbs specific for the 100 kDa protein used very similar or identical germline SM7 VH genes. In addition to using the same germline D and JH genes, they also exhibited identical VH-D-JH joins, despite originating from distinct fusions. Analysis of light chains also showed some restriction by preferential use of germline V kappa 4 and J kappa 5 genes. Together, these results suggest that the restricted antibody repertoire characteristic of mouse fetal and neonatal B cells is also reflected in the production of anti-lymphocyte antibodies. These B cells appear consistently in early development, use germline V genes, and express a characteristic VH-D-JH join.

Amino Acid Sequence↗
PubMed1992

The expression of the mouse VpreB/lambda 5 locus in transformed cell lines and tumors of the B lineage differentiation pathway.

The expression of RNA transcripts from two pre B lymphocyte related genes, VpreB and lambda 5, has been studied in a series of transformed cell lines which appear frozen at different states of B lineage differentiation, from early progenitors to surface Ig positive B cells. In the HAFTL-1 cell line, which arose from fetal liver by transformation with a retrovirus containing the Hras oncogene, Northern analysis of poly A+ mRNA as well as in situ hybridization of RNA in single cells revealed that lambda 5 and VpreB are already expressed at the progenitor stage and increase in expression as the progenitors differentiate to precursor (preB) cells, or are turned off as the progenitors differentiate to myeloid cells. Continued rearrangements of Ig genes in pre B cell lines leading to Ig expression on the surface of NFS-5 pre B cells do not influence the continued expression of VpreB and lambda 5. Surface Ig-positive B lineage cell lines also express the pre B-related genes. Both Ly1+ as well as Ly1- pre B cells are VpreB- and lambda 5-positive. Lipopolysaccharide (LPS) stimulation of 70Z/3 pre B cells does not turn off lambda 5 expression. It therefore appears that, at least in transformed cell lines, the expression of VpreB and lambda 5 is not directly regulated by the expression of microH, kappa L, or lambda L chains, LPS reactivity, or the Ly1 surface antigen. Fusion of plasmacytoma cells with normal pre B cells to generate pre B hybridomas leads to down-regulation of VpreB/lambda 5 expression.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗