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J J Cebra

Publications and source records attributed to J J Cebra.

At least 19 recordsLinked to original sources
PubMed1995

Spleen cells from antigen-minimized mice are superior to spleen cells from germ-free and conventional mice in the stimulation of primary in vitro proliferative responses to nominal antigens.

T lymphocytes from mice reared under conditions of differential exposure to food, environmental and microbial antigens were compared for phenotypic shifts that may be associated with prior exposure to antigens as well as functional variations in the ability to respond to antigens de novo. While the intra-epithelial CD8 T cell compartment was found to differ significantly in the type of T cell receptor predominantly expressed, CD4 T cells from various lymphoid organs of conventionally reared specific pathogen-free (CL-SPF) mice showed only subtle phenotypic differences from cells obtained from antigen-minimized germ-free (AF) and germ-free (GF) mice. Cells derived from mice exposed to a reduced antigen load exhibited primary in vitro proliferative responses to antigens such as dinitrophenyl-keyhole limpet hemocyanin which were significantly enhanced when compared with similar responses of cells from conventional mice. In cell mixing experiments, differences in the reactivity of T cells from the spleens of AF, GF and CL-SPF mice were dependent on the source of the spleen cells employed as antigen-presenting cells (APC). Experiments in which the T cell population was held constant revealed that, as APC, spleen cells from AF mice were most often superior to spleen cells from GF mice which were in turn considerably better than a similar population from SPF mice. We conclude that the enhanced primary reactivity of spleen cells from AF mice to nominal antigen in vitro is likely to be the result of a difference in the function and/or regulatory activities of the cell population employed as APC in this investigation.

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PubMed1995

Role of maternal antibody in the induction of virus specific and bystander IgA responses in Peyer's patches of suckling mice.

Reciprocal crossings of C.B17 scid/scid and congenic BALB/c (+/+) mice generate genetically identical, immunocompetent F1 scid/+ mice that develop in either the absence or influence of passively transferred maternal immunity. By exchanging F1 scid/+ litters at birth among scid/scid, non-immune or reovirus immune BALB/c mothers we examined the relative ability of placental or colostral/milk transfer of virus specific maternal antibodies to interfere with reovirus immunization of the neonatal gut associated lymphoid tissues (GALT). Our data demonstrate that the Peyer's patches (PP) in 10-day-old mice are competent to support thymus dependent responses to acute reovirus stimulation that include the rapid (within 3 days) development of specific IgA plasma cells and the subsequent initiation of PP germinal center reactions. These neonatal mucosal immune responses occur independently of coincident specific maternal immune responses as evidenced by the identity of the reovirus specific responses engendered in F1 scid/+ pups of scid/scid versus +/+ mothers. However, transfer of pre-existing reovirus specific maternal antibody in milk via nursing on a reovirus immune (foster) mother completely abrogated reovirus specific neonatal IgA responses; while placental transfer of specific maternal antibody alone did not interfere with the immunization of the neonatal GALT with enteric reovirus. Reovirus challenge of 10-day-old mice was associated with a substantial bystander IgA response. Possible mechanisms responsible for the induction of the observed bystander IgA responses are discussed.

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PubMed1995

Commensal enteric bacteria engender a self-limiting humoral mucosal immune response while permanently colonizing the gut.

We have employed a germfree mouse model to study the development and persistence of a humoral mucosal immune response to a gram-negative murine commensal organism, Morganella morganii. M. morganii bacteria rapidly colonize the gut, resulting in hypertrophy of Peyer's patches (PP), including germinal center reactions (GCR), and the development of specific immunoglobulin A (IgA) responses detected in vitro in PP fragment cultures and by ELISPOT assays of lamina propria cells. The GCR peaks 14 days after infection and begins to wane thereafter. Upon colonization, the organisms successfully translocate to the mesenteric lymph node and spleen, but the number of translocating bacteria begins to drop with the onset of a specific IgA response. A clonal B-cell microculture technique was used to determine the frequency of specific IgA plasmablasts and IgA memory cells. The frequencies of preplasmablasts were seen to be higher in the earlier stages of germinal center development, whereas the frequencies of antigen-specific memory cells appeared to remain at a relatively constant level even after 193 days postmonoassociation. We suggest that a successful secretory IgA response can attenuate chronic stimulation of GCR even though the bacteria persist in the gut. The observed developing hyporesponsiveness to a chronically present commensal organism may be relevant to the use of bacterial vectors for mucosal immunization.

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PubMed1995

Characterization of cytotoxic cells from reovirus-infected SCID mice: activated cells express natural killer- and lymphokine-activated killer-like activity but fail to clear infection.

Severe combined immune deficient (SCID) mice infected orally with reovirus type 1/L die of hepatitis. Leukocytes bearing the cell surface antigens Thy-1.2 and asialoGM-1 (AsGM1) accumulate in the livers of infected animals. These cells display lytic activity toward natural killer-sensitive (YAC-1) and -resistant (P815) cell lines and murine hepatoma line Hepa 1/A1. Although these cells have the capacity to lyse infected hepatoma targets, they cannot clear the virus.

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PubMed1991

The preference for switching to IgA expression by Peyer's patch germinal center B cells is likely due to the intrinsic influence of their microenvironment.

This study was aimed at determining whether the chronically activated physiologic state of Peyer's patch (PP) tissue is primarily responsible for the IgA isotype preference expressed by PP germinal centers (GC) and memory B cells. We have used reovirus type 1/Lang to stimulate acute, de novo GC reactions in lymph nodes (LN) or PP to test the possibility that the surface (s)IgA component of enteric responses is peculiar to the local gut microenvironment whether or not PP are in a state of chronic activation. GC were raised in PP of germ-free mice by oral administration of virus and in lymph nodes (LN) of conventionally reared mice by local parenteral infection. Transient GC reactions were found to develop with similar time courses in both PP and LN after both primary and secondary local infections with reovirus. sIgA+ B cells, which were the major non-sIgM+/sIgD+ population found to arise in GC of PP, were not found in the LN. In LN, sIgG1+ B cells comprised the predominant non-IgM/IgD bearing population that arise after local infection. Lymphoid fragment cultures of PP initiated in vitro as early as 5 days after in vivo infection contained detectable secreted reovirus-specific IgA, whereas IgG1 but no IgA was found in LN cultures. Northern blot analysis to detect C alpha and C gamma 1 germline transcripts further substantiated a site-related bias in the expression of non-IgM/IgD isotypes that was manifest within a few days after infection. In summation, these observations taken together suggest that the preference for generating sIgA+ B cells in PP may be the result of intrinsic features of their gut microenvironment.

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PubMed1991

Responses of single germinal-center B cells in T-cell-dependent microculture.

B cells purified from the germinal centers (GCs) of murine Peyer's patches can be stimulated in a clonal microculture containing helper T cells and dendritic cells to divide and secrete immunoglobulin. Intraclonal isotype switching occurs, and a variety of immunoglobulin isotypes, including IgA, is secreted. Memory cells, which generate clones secreting IgA exclusively, are only rarely identified in the GC B-cell subset. Such memory cells can, however, be readily identified among unfractionated Peyer's patch B cells, and in non-GC subsets of B cells. The results suggest that the GC does not contain IgA memory cells that can be restimulated in vitro to secrete only IgA. When division of GC B cells is prevented by irradiation or aphidicholin treatment, a large subset that secretes IgA as the sole immunoglobulin isotype is seen, and the output of presumably single B cells is large enough to be scored by RIA. Both helper T cells and dendritic cells are required for the phenomenon. The data indicate that commitment to IgA secretion occurs in Peyer's patch GCs and suggest that the prolific cell division known to be supported in GCs may forestall terminal differentiation of preplasmablasts to immunoglobulin secretion.

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PubMed1991

Molecular genetic features reflecting the preference for isotype switching to IgA expression by Peyer's patch germinal center B cells.

It has proven difficult to evaluate the functional potential of germinal center (GC) B cells, including those from Peyer's patches (PP), by either in vivo or in vitro methods. Thus, rather than assess secreted Ig product as an indicator of functional potential we have instead sought to detect mRNAs related to the various Ig heavy chains in GC B cells from PP by in situ hybridization. We have found that the GCs of PP contain the vast majority of B cells with easily detectable levels of mRNA alpha. These levels are intermediate between those of small resting B cells and plasmablasts. When PP B cells are enriched for cells bearing GC markers, approximately 50% contain mRNA mu and 40% mRNA alpha. Similar enrichment for sIgA+ B cells gave 50% of cells with easily detectable mRNA alpha and few if any positive for mRNA mu. The sizes of these mRNAs were similar to those encoding the membrane and secretory form of mu and alpha chains. No C alpha germ-line transcripts could be detected by Northern analyses using a probe for sequences 5' to the alpha switch regions. Finally, GC and sIgA+ cells from PP also showed the absence of a portion of their genomic DNA for CH genes 5' of C alpha. Thus, it seems likely that most of the GC cells expressing mRNA alpha have undergone conventional VDJ recombination to C alpha at the DNA level in order to switch to the expression of IgA. Our findings reflect the extraordinary preference for switching to IgA by GC cells in PP.

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PubMed1991

Use of Peyer's patch and lymph node fragment cultures to compare local immune responses to Morganella morganii.

Lymphoid tissue fragment cultures were established to analyze the differentiative processes among B cells in Peyer's patches (PP) and peripheral lymph nodes (PLN), especially those in germinal centers. PP cultures from both conventionally reared mice and formerly germ-free mice colonized with Morganella morganii could be maintained for greater than 12 days with continued B-cell division, especially among cells binding high levels of peanut agglutinin, a characteristic of germinal center cells. PLN cultures from conventionally reared mice injected with a heat-killed vaccine of M. morganii could be maintained for the same amount of time. Over this period, PP cultures continued to secrete immunoglobulin A (IgA) as well as smaller amounts of IgM. PP cultures from formerly germ-free mice colonized with M. morganii showed net increases of IgA antiphosphocholine (anti-PC) antibodies with avidities as high as those of the prototypic T15 monoclonal antibody. Similar PLN fragment cultures from conventionally reared mice given footpad injections of M. morganii showed net increases of IgM and IgG anti-PC antibodies in the culture fluid. Thus, although M. morganii stimulated lymphoid tissues in vivo to produce an anti-PC response in vitro when given by either the oral or the parenteral route, the antibody isotypes differed between PP and PLN fragment cultures. Fragment culturing may offer a complementary and simpler way to detect a local secretory IgA response than does either measuring IgA antibody in secretions or detecting IgA antibody in the cytoplasm of plasma cells in the lamina propria of gastrointestinal or respiratory tissue.

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PubMed1990

CD8 lymphocyte subpopulations in Peyer's patches induced by reovirus serotype 1 infection.

CD8 lymphocyte population heterogeneity has been examined by using reovirus serotype 1, strain Lang (reovirus 1/L) as a model infection. We have previously reported that gut mucosal infection with reovirus stimulates the appearance of virus-specific cytotoxic T cell precursors (pCTL) in Peyer's patches (PP). The effectors that mediate reovirus-specific cytotoxicity were found to express both the Thy-1 and CD8 Ag and were MHC-restricted in their recognition of reovirus Ag. To further characterize the virus-specific precursor and effector cells we have analyzed PP cells for the expression of a novel surface Ag (termed germinal center and T cell Ag (GCT)) found on germinal center B cells and a subpopulation of CD8+ T cells. Gut mucosal infection with reovirus 1/L is capable of increasing the proportion of GCT+ CD8+ T cells in PP. Positive selection as well as depletion of GCT+ cells has demonstrated that pCTL can express this Ag, and depletion experiments have demonstrated that effector CTL express the GCT Ag. Thus, a subpopulation of GCT+ cells have been identified as Ag-specific precursor and effector CTL. These observations indicate that the expression of the GCT Ag may provide a means to identify recently stimulated pCTL or effector CTL in gut mucosal tissues.

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