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J J Cebra

Publications and source records attributed to J J Cebra.

At least 73 records · Page 4Linked to original sources
PubMed1987

Secondary intratracheal infection of mice with Mycoplasma pulmonis generates IgG1 memory B cells.

Mycoplasma pulmonis, a rodent respiratory pathogen, was used to study the immune response in the bronchus-associated lymphoid tissue (BALT) and other lymphoid tissues. Infection of BALB/c mice intratracheally (i.t.) with M. pulmonis results in an increased frequency of antigen-sensitive B cells at the site of priming. Upon secondary i.t. challenge, the frequency of antigen-specific B cells rises significantly in BALT, in peripheral blood and, to a lesser extent, in lymphoid tissues distal to the site of priming, i.e., spleen and Peyer's patches. The predominant isotype of anti-M. pulmonis antibody expressed by clones grown in thymus-dependent splenic fragment cultures from B cells taken from all tissues is IgG1. Elimination of accompanying T cells in inocula from euthymic BALB/c mice or lack of T cells at the time of in vivo priming of athymic mice does not change the isotype profile of clones grown from M. pulmonis-specific B cells. The splenic fragment cultures used to grow these clones do not distort the isotype display towards IgG1 expression, since clones grown from either primed or unprimed B cells of other specificities (i.e., trinitrophenyl--TNP) express any or all isotypes in a variety of combinations. The majority of M. pulmonis-specific clonal precursor B cells are sIgG1+/IgD-. All these findings suggest that the potential to give rise to predominantly IgG1-secreting clones in vitro is intrinsic to the M. pulmonis-specific memory B cells primed in vivo.

Animals↗
PubMed1986

CH isotype switching in B cell differentiation.

We have functionally defined a number of B cell subsets that likely represent B cells at different stages of development, based on the pattern of CH isotypes expressed by their clones in splenic fragment or microcultures and on those factors necessary in culture to support the growth of a clone displaying a particular isotype or set of isotypes. Our observations are consistent with isotype switching being a stochastic process which results in the occurrence of progressive isotype restriction in members of a diversifying clone. The surface marker best predictive of the pattern of isotypes a clone may secrete is the sIg isotype of its B cell precursor. Those B cells that have switched to the expression of non-IgM isotypes in vivo can be stimulated in vitro in splenic fragments to give an antibody-secreting clonal culture but so far cannot be stimulated in a microculture of dispersed cells that supports clones secreting IgM alone or with other isotypes.

Animals↗
PubMed1985

Antigens apparently nonimmunogenic for xid/Y mice cause the development of specific splenic plasmablasts and of fusion partners for SP2 cells giving hybridomas that secrete antibodies.

Although xid/Y mice fail to make a detectable primary antibody response to a variety of antigens such as Type III pneumococcal capsular polysaccharide (SIII), 2,4, 6-trinitrophenyl (TNP)-Ficoll, pneumococcal C carbohydrate, group A streptococcal vaccine and several kinds of related antigenic determinants such as phosphorylcholine (PC) and N-acetyl-glucosaminyl (GlcNAc), even when the latter are coupled to hemocyanin (Hy), they do show: (a) an antigen-dependent development of splenic B cells which can act as successful, productive fusion partners for SP2 cells giving hybridomas making monoclonal anti-SIII, anti-PC, anti-GlcNAc, anti-TNP, etc., and (b) an antigen-dependent appearance of antigen-binding plasmablasts in their spleens. The frequencies of specific B cells arising in xid/Y males with either of these properties are of the same order of magnitude as those found in immunocompetent xid/X female littermates. Further, both PC-Hy and GlcNAc-Hy prime xid/Y and xid/X mice for quantitatively and qualitatively similar secondary responses. All three of these expressions of a specific, primary response occur in xid/Y mice in the absence of any rise in circulating antibodies. The properties of successful, productive normal fusion partners leading to secretory hybridoma lines are unknown. Thus we cannot decide whether the antigen-binding plasmablasts that arise in xid/Y mice can also play the role of productive fusion partners. Neither do we know whether the development of specific IgM and IgG3 plasmablasts in xid/Y mice after antigen stimulation is an abnormality reflecting the xid mutation. It cannot be excluded that the development of productive fusion partners, of nonsecretory plasmablasts and of memory cells are all interrelated and reflect a process that also normally occurs in xid/X, X/X and X/Y mice following similar immunization regimens. It is tempting to speculate that such cells initially responding may lag in the development of normal secretory mechanisms and that the "transformed" fusion partner may complement this deficiency.

Acetylglucosamine↗
PubMed1985

Isotype commitment of B cells and dissemination of the primed state after mucosal stimulation with Mycoplasma pulmonis.

Live Mycoplasma pulmonis organisms were used to examine the immune response in the bronchus-associated lymphoid tissue after primary and secondary challenge with M. pulmonis, to study the dissemination of the primed state to distal tissues (i.e., spleen, peripheral blood, and Peyer's patches), and to determine whether the chronic antigenic stimulation accompanying infection influences the isotype potential and commitment of the primed B cells recovered from the various tissues. We have shown that exposure to M. pulmonis by a variety of routes results in a generalized rise in frequency of T-dependent, antigen-sensitive B cells in all lymphoid tissues. The route of secondary exposure to M. pulmonis was found to markedly increase the frequency of M. pulmonis-specific B cells in the bronchus-associated lymphoid tissue relative to that in the Peyer's patches after intraduodenal but not intratracheal challenge. A substantial rise in the number of M. pulmonis-sensitive B cells in the peripheral blood suggests that the dissemination of the primed state, at least in part, is due to B-cell migration via lymph and blood from local sites exposed to M. pulmonis. The majority of T-dependent clones generated by M. pulmonis-specific B cells secrete exclusively immunoglobulin G1 (IgG1). We have demonstrated that the exaggerated IgG1 response was not due to the accompanying viable donor T cells in the inoculum. The predominance of IgG1 was also demonstrated in clones from the bronchus-associated lymphoid tissue of athymic BALB/c mice that were primed with M. pulmonis. Thus, we can infer that functional T cells are not required for the development of specific B cells with the potential for IgG1 expression at the time of in vivo priming. When anti-trinitrophenyl- and anti-M. pulmonis-specific clones were generated in the same splenic fragment cultures stimulated by trinitrophenylated M. pulmonis, only the M. pulmonis-specific clones showed exaggerated IgG1 expression. Therefore, we conclude that the exaggerated IgG1 response accompanying M. pulmonis infection of euthymic mice seems to be dependent, at least in part, on an intrinsic property of the B cells that develop during this antigenic stimulation.

Animals↗
PubMed1984

Changes in specific B cells and the dissemination of the primed state in vivo following antigenic stimulation by different mucosal routes.

Immunologic dogma holds that the adaptive and long-term potential of the antibody response is fashioned by antigen-dependent, selective clonal proliferation of specific B cells and the retention of some which may undergo a second round of antigen-stimulated clonal expansion with antibody production. Apparently, the short-term, immediate consequences of an antibody response depend on the mix of isotypes displayed in vivo upon exposure to antigen. This latter seems to be clearly regulated by T cells, but it is also likely that the isotype potential of a B cell population and its future possible display of isotypes is linked to the initial, antigen-dependent proliferative phase in the development of an antibody response. In vitro analysis at limiting dilutions of specific B cells primed in vivo has led to the operational definition of IgA-committed cells. These B cells increase in frequency following chronic or acute antigenic stimulation of gut mucosa and have the potential to proliferate again in the presence of antigen and TH(Ag) cells to produce exclusively IgA. A general relationship exists between mucosal or parenteral priming of B cells and their potentials to express IgA and/or IgE--both isotypes appear to be likely products of secondary B cells and frequently both can be expressed by the same clone activated by a second-round of T-dependent antigenic stimulation. Cross priming--exposure of GALT or BALT leading to secondary B cells in the opposite mucosal lymphoid tissue--suggests an inherent antagonism between development of allergic (IgE) and putative allergy blocking (IgA) potentials.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Interrelationship of primed B cells with the potential for IgE and/or IgA expression.

The relationship between the pathways of B cell differentiation leading to IgE or IgA expression was analyzed by assessing the isotype potential of primed B cells as revealed over many generations of clonal outgrowth in splenic fragment cultures. Cells from (CBA/N X BALB/C) F1 male and female mice primed with phosphocholine (PC)-hemocyanin (Hy) and given a secondary stimulus with PC-Hy or PC-determinants via an Ascaris infection gave rise to a large proportion (25-48%) of clones which expressed anti-PC IgE along with any one or mixture of other isotypes, especially IgG and/or IgA. Accompanying the appearance of these cells in the Peyer's patches following Ascaris infection was the steady rise in IgA committed cells over a 12 week period. The potential to express IgE seems to be a normal feature of the development of secondary or memory cells. The coexpression of IgE randomly with all other isotypes supports a linear rather than a branched pathway of B cell differentiation. Ascaris or PC-determinants given to F1 mice were not unique in their ability to prime cells with the potential for IgE expression. Stimulation of BALB/c mice with two low doses of N-acetyl-glucosamine-conjugated hemocyanin (GlcNAc-Hy) primed cells in vivo generated a high proportion (63%) of clones in vitro that expressed IgE and most of these exclusively coexpressed IgA (16/26) suggesting a progressive restriction in isotype potential. Cells which gave rise to IgE producing clones specific for the priming hapten did not support the expression of IgE by clones of other specificities costimulated in vitro (anti-inulin, anti-beta-galactosyl). Thus the potential to express IgE seems to be both an inherent property of the B cells and under hapten-specific or hapten-linked regulation.

Animals↗
PubMed1982

Metabolism of immunoglobulin A in lactating mice: origins of immunoglobulin A in milk.

The metabolism of albumin and IgA was studied in normal and lactationg mice. Lactation resulted in significant changes in the metabolism of these proteins. The serum albumin concentration was lowered from 47 mg/ml in normals to 24 mg/ml in lactating mice. However, only a slight decrease in the serum concentration of IgA was observed during lactation. The proportion of polymeric and monomeric IgA in serum and milk was evaluated by gel exclusion chromatography. The onset of lactatin led to a rise in the proportion of polymeric IgA (P-IgA) in serum from 37% to 51%. The proportion of P-IgA in milk was 65% and remained constant throughout lactation. P-IgA and albumin were shown to be efficiently transferred from the serum of lactating mice into their milk. Serum decay studies were performed to evaluate the turnover of the serum pools during lactation. The rates of disappearance from the serum of isotopically labeled albumin and P-IgA were observed to increase dramatically during lactation, suggesting that both of these two mild proteins might be derived at least in part from the serum. The sites of synthesis of mild IgA (local vs. extra-mammary gland) were evaluated by determining the extent of dilution of isotopically labeled serum IgA during transport through the mammary gland into the milk. Early in lactation, the majority of the IgA in mouse milk appeared to be derived from distant sites and transferred via the blood to the mammary gland. However, by day 8 of lactation, the isotopically labeled P-IgA in milk was significantly diluted by the IgA synthesized in the mammary gland. Albumin and IgG were not diluted by local synthesis indicating that these proteins were exclusively serum-derived.

Animals↗
PubMed1982

Patterns of isotype expression by B cell clones responding to thymus-dependent and thymus-independent antigens in vitro.

It was found that the Type 2 thymus-independent (TI-2) antigens bacterial levan, trinitrophenyl-Ficoll, and pneumococcal carbohydrate vaccine (PnC) stimulate clonal expansion and antibody secretion in splenic fragments from either hemocyaninprimed or unprimed irradiated recipients bearing B cells from unprimed donors. The in vitro stimulation with TI-2 antigens leads to the expression of isotype switching and provides a more balanced variety of isotypes than is usually observed in vivo. Still, some characteristic patterns of isotypes expressed in vivo to either TI-2 or thymus-dependent (TD) antigens are preserved in vitro. Frequencies of phosphocholine (PC)-reactive B cells responding to either PnC or to PC-hemocyanin (PC-Hy) suggest an appreciable overlap in populations responding to these TI and TD forms of antigen. The existence of a population responsive to either form of PC determinant is supported by the observation that many clones arising in the presence of both forms of antigen express patterns of isotypes that appear as summations of those distinct patterns shown by clones responding to only one form or the other. These data suggest that PC-Hy- and PnC-responding cells may derive from a linear rather than a branched pathway of B cell development and that expression of isotype switching over the lifetime of a developing B cell clone may be regulated in a manner dependent on the form of the stimulating antigen.

Animals↗
PubMed1982

Phosphorylation of lymphocyte myosin catalyzed in vitro and in intact cells.

Myosin has been isolated from guinea pig B-lymphocytic leukemia cells (L2C). The myosin has been enzymatically phosphorylated and dephosphorylated in vitro using both heterologous and lymphocyte-derived enzymes. Both the heavy chain and 20,000-dalton light chain of lymphocyte myosin are phosphorylated in vitro. Phosphorylation of myosin enhances actin-activated ATPase activity. Phosphorylation of myosin in murine lymphocytes was analyzed by use of a novel technique for rapid immunoprecipitation of myosin from cell extracts. Both the heavy chain and 20,000-dalton light chain of myosin are phosphorylated in intact cells. Addition of antibody reactive with cell-surface immunoglobulin to lymphocyte populations enriched for B cells stimulates locomotion of these cells and also increases the quantity of 32P isolated in association with the 20,000-dalton light chain of lymphocyte myosin, when 32Pi was present in the medium. In addition, an unidentified, phosphorylated polypeptides with a molecular mass of 22,000 daltons is co-isolated with myosin from cells by rapid immunoprecipitation. These results are consistent with the hypothesis that phosphorylation of myosin may contribute to regulation of movements performed by lymphocytes which are related to their participation in immunologic reactions.

Actins↗
PubMed1982

IgA-producing hybridomas are readily derived from gut-associated lymphoid tissue.

Eight hybridomas secreting IgA monoclonal antibodies were obtained by using gut-associated lymphoid tissue as a primed plasmablast source. IgA secretors are obtained at higher frequencies by this technique than by conventional splenic fusions. This technique provides useful tools for the study of mucosal protection, and it demonstrates that exaggerated potential of gut-derived B cells, compared to splenic B cells, for IgA expression.

Animals↗
PubMed1981

Affinity labeling of residues within Hv2 of guinea pig anti-azobenzenearsonate antibodies of different isotypes and from different strains.

Anti-p-azobenzenearsonate (ARS) antibodies of IgG1 and IgG2 isotypes produced in inbred strain 13 and strain 2 guinea pigs were affinity labeled with N-(bromoacetyl)-3-[(p-arsonophenyl)azo]-L-tyrosine (BAAT) or N-(bromoacetyl)-p-arsanilic acid (BAA). BAAT was shown to modify approximately 50% of the binding sites specifically and BAA approximately 30%. Both reagents preferentially modified residues in the heavy (H) chain to the extent that it contained over 80% of the affinity label associated with the native molecule. At least 80% of label borne by the variable domain of the H chain (VH) was found in the second hypervariable region (Hv2). BAAT labeled all anti-ARS antibodies exclusively at position N-59, which contains a lysyl residue. BAA labeled predominantly tyrosine at N-57 and, to a lesser extent, lysine-59 and tyrosine-50. Comparison of Hv2 sequences in anti-ARS and in antibodies reactive with other haptens has shown that tyrosine at N-50 and N-57 as well as lysine at N-59 is distinctive of antibodies with anti-ARS specificity, thus implying their involvement in antigen binding. The predominant sequence of Hv2 was identical in anti-ARS IgG1 and IgG2 molecules induced in either inbred guinea pig strain following either carrier priming or conventional immunization. Although limited variability does occur among the various populations of anti-ARS antibodies in certain residue positions in Hv2, no significant differences in the binding affinities or in the indexes of heterogeneity were seen among the various kinds of anti-ARS antibodies.

Affinity Labels↗
PubMed1981

Special features of the priming process for a secretory IgA response. B cell priming with cholera toxin.

Administration of cholera toxin/toxoid by either intraduodenal or parenteral routes increases the frequency of antigen-sensitive B cells in Peyer's patches (PP) and in distant lymphoid tissues greater than 50-fold. The special feature of mucosal priming with toxin is its unique effectiveness at generating secondary B cells, whose progeny express IgA exclusively, and such cells appear in highest frequency in PP and in appreciable numbers in spleen. Thus, this deliberate intraduodenal immunization seems to mimic the natural priming process induced by enteric bacterial colonization, which we have postulated to account for the high frequencies of IgA-committed cells specific for bacterial determinants in the PP of conventionally reared mice. furthermore, as a result of intraduodenal immunization, antigen-specific memory B cells are disseminated to sites distant form that of antigen application, including the lymphoid follicles associated with the respiratory mucosa. Direct antigenic stimulation of cells in the PP therefore results in effective cross-priming among mucosal and systemic sites through division, differentiation, and disemination of antigen-sensitive secondary B cells.

Animals↗