Search PubMed⌕ Search

Biomedical subjects

S T Ju

Publications and source records attributed to S T Ju.

At least 109 records · Page 6Linked to original sources
PubMed1978

Structural studies on induced antibodies with defined idiotypic specificities. VI. Amino terminal sequences of the heavy and light chain variable regions of anti-p-azophenylarsonate antibodies from A/J mice suppressed for a cross-reactive idiotype.

Previous studies in this series have been directed toward the elucidation of the heavy and light chain variable region structures of antibodies raised in A/J mice to the p-azophenylarsonate (Ar) hapten, certain of which bear a cross-reacting idiotype. The present study concerns an analysis of anti-Ar antibodies that arise in A/J mice suppresed for a cross-reacting idiotype. The results indicate that when an idiotype is suppressed and the animal subsequently hyperimmunized, the resultant antibodies are "deviated" into different V-region subgroups, both in the heavy and light polypeptide chains. The study presents the first primary structural analysis of a humoral immune response that has been manipulated by an idiotypic reagent.

Amino Acid Sequence↗
PubMed1977

Complete inhibition of the expression of an idiotype by a mechanism of B-cell dominance.

Mice of the C.AL-20 strain, which express genes controlling CH regions of the AL/N strain on a BALB/c background, normally synthesize antibodies to the p-azophenylarsonate group (anti-Ar antibodies) with an idiotype characteristic of the A strain. The synthesis of the idiotype, as quantitated by a sensitive assay, can be completely inhibited by the transfer of leukocytes from BALB/c mice producing anti-Ar antibodies, which lack the idiotype. A number of control experiments show that the inhibition is not attributable to suppressor T cells and that the synergistic action of such cells is not required. The results indicate that B-cell dominance, mediated by secondary cells, can completely prevent the expression of unprimed cells with receptors of the same specificity. It is uncertain whether this effect is due entirely to selective capture of antigen by the secondary cells, or whether some type of active suppression by B cells is involved.

Animals↗
PubMed1977

Presence on idiotype-specific suppressor T cells of receptors that interact with molecules bearing the idiotype.

All A/J mice produce anti-p-azophenylarsonate (anti-Ar) antibodies, some of which share a cross-reactive idiotype. The idiotype can be suppressed by treatment with anti-idiotypic antiserum before immunization, although normal concentrations of anti-Ar antibodies are synthesized. We have previously reported that such suppressed mice, if hyperimmunized and then allowed to rest, contain up to 10% of splenic T cells which form rosettes with autologous RBC coated with Fab fragments of anti-Ar antibodies bearing the idiotype. Our present results indicate that the rosette-forming T cells include the idiotype-specific suppressor T-cell population. The suppressive activity is largely depleted by removal of the rosette-forming lymphocytes, and the rosettes themselves are highly suppressive. The data do not establish whether all of the idiotype-specific rosette-forming cells are suppressor cells. The system may provide a source of large numbers of suppressor cells for further study, and facilitate investigation of the mechanism of generation of idiotype-specific suppressor cells.

Animals↗
PubMed1977

Transfer of idiotype suppression and idiotypes by leukocytes from ascitic fluids.

A procedure is described for producing ascites containing both high concentrations of antibodies and immunologically active leukocytes. In mice that were immunologically suppressed with respect to a cross-reactive idiotype, the ascitic cells were found to be very active in adoptively transferring the suppressed state to mildly irradiated, syngeneic recipients and simultaneously transferring the capacity to produce the "private" idiotype characteristic of the donor's anti-p-azophenylarsonate antibodies. The participation of both T and B cells is therefore suggested. As few as 2 x 10(6) cells were sufficient for suppression and for inducing the production of the private idiotype in the recipient, in concentrations comparable to that of the donor mouse. A single donor can thus be used to colonize many recipients with the private idiotype, without sacrifice of the donor. The method should be useful in structural studies of antibodies of a given specificity with different idiotypes, and for investigations of the mechanism of idiotype suppression, as well as other studies in cellular immunology.

Animals↗
PubMed1977

Two str1cturally similar haptens each induce a different inherited idiotype.

When mice of the A/J strain were immunized with azobenzenearsonate (ABA) directly coupled to a protein, they produced antibodies that share an inherited cross-reactive idiotype (CRI). In the antigenic determinant that induces CRI, ABA is very probably coupled to tyrosine, and the structure that protrudes from the polypeptide backbone has two benzene rings and a molecular weight of 419. When this same structure is separated from the polypeptide backbone by a spacer of 99 daltons, it induces a different inherited idiotype (ABA-HOP-e) in the same strain of mice. Our data suggest that antibodies with the idiotype CRI recognize the terminal benzene ring and the azo group, but do not fit closely around the second ring structure. Antibodies with the idiotype ABA-HOP-e have fine specificity for both benzene rings. Both idiotypes are inherited and both are linked to genes controlling constant regions of the heavy chains.

Animals↗
PubMed1977

Production of large amounts of antibodies, complement, and leukocytes in ascitic fluids of guinea pigs.

A method is described for the production in guinea pigs of large amounts of ascitic fluid containing non-specific IgG, antiprotein antibodies, complement, other serum proteins and leukocytes. The method is an adaptation of a procedure previously applied to mice. A major difference is the extended schedule of inoculations required for the induction of ascites in guinea pigs; a requirement for boosting with antigen intradermally while repeatedly inoculating adjuvant intraperitoneally; and the much larger quantities obtained. The average yield of ascitic fluid, when antigen was not used, was 113 ml per animal, and the average yield of IgG was 0.87 g. With antigen (keyhole limpet hemocyanin) the average yields were 143 ml and 1.6 g of antibody per guinea pig. Complement titers were 41 to 74% of those in serum. The number of leukocytes per ml of ascites ranged from 7 X 10(6) to 20 X 10(6). The method should be useful for the production of large amounts of leukocytes, antibodies and other serum proteins from a small colony of laboratory animals. In addition, cells can be obtained without the need to sacrifice the animal.

Animals↗
PubMed1977

Binding to idiotypic determinants of large proportions of thymus-derived lymphocytes in idiotypically suppressed mice.

All A/J mice immunized with a conjugate of p-azophenylarsonate groups to keyhole limpet hemocyanin produce antibodies against azophenylarsonate, some of which share a crossreactive idiotype. The appearance of the idiotype can be suppressed, without reducing the response against azophenylarsonate, by injecting rabbit anti-idiotypic antibodies prior to immunization. We have now observed that mice suppressed in this way, or by adoptive transfer of leukocytes from other suppressed mice, and then immunized with the hemocyanin-azophenylarsonate conjugate, possess high proportions (up to 14%) of lymphocytes that form rosettes with A/J erythrocytes coated with Fab fragments possessing the idiotype. Idiotypic specificity was demonstrated by various experiments. Most of all of the rosette-forming lymphocytes appear to be thymus-derived lymphocytes (T cells). Treatment of T cells with trypsin eliminated the capacity to form rosettes, which was restored on standing overnight in medium. Thus, the receptors are synthesized by the cells and are not passively adsorbed. Treatment of mice with anti-idiotypic antiserum without antigenic stimulation did not elicit substantial numbers of rosette-forming cells. The requirement for antigen suggests that antigen-idiotype complexes may be a stimulatory agent. A prolonged rest period after immunization of suppressed mice was required for the induction of high percentages of rosette-forming cells. Rosette formation provides a convenient method for studying factors that induce the formation of idiotype-specific T cells.

Animals↗
PubMed1977

Relation of a cross-reactive idiotype to genetic control of the immune response.

Antibodies elicited in strain A mice by immunization with keyhole limpet hemocyanin-p-azophenylarsonate (KLH-Ar) produce anti-Ar antibodies, some of which share a cross-reactive idiotype (CRI); in general, 20 to 70% of the antihapten antibody population carries the idiotype. Large amounts of antibody can be produced by the induction of ascitic fluids, using a 9:1 ratio of complete Freund's adjuvant (CFA) to antigen. Antibodies with the CRI can be isolated by isoelectric focusing from selected mice that have produced a high concentration of the CRI. The H chains exhibit a single homogeneous sequence through the first hypervariable region and, when isolated from a large number of individual mice, appear to be invariant in the first framework region. These findings indicate that somatic mutation is not a significant factor in the determination of framework sequences. Appearance of the CRI can be suppressed in adult A/J mice by administration of rabbit anti-idiotypic antiserum prior to immunization. Such suppressed mice produce normal concentrations of anti-Ar antibodies lacking the CRI. Anti-idiotypic antibodies produced against such antibodies failed to show cross-reactivity with anti-Ar antibodies arising in idiotypically suppressed or nonsuppressed A/J mice. The great sensitivity of the assay indicates that the number of such "private" idiotypes, all present on anti-Ar antibodies of a single strain, must be extremely large; this supports a somatic mechanism for the generation of diversity. The "private" idiotypes arising in suppressed, hyperimmunized mice can be adoptively transferred into multiple, irradiated (200 R) recipients by injections of spleen cells or of cells from ascitic fluids. The use of ascitic fluids permits the rapid production of a colony of mice bearing the idiotype. This should facilitate structural studies of a variety of idiotypically different molecules sharing the same (anti-Ar) specificity, as well as studies of the mechanism of suppression.

Amino Acid Sequence↗
PubMed1976

Production of large amounts of antibodies in individual mice.

A method is described for the elicitation of substantial amounts of anti-hapten and anti-protein antibodies in ascitic fluids of individual mice of various strains. The method utilizes repeated i.p. inoculations of u.5-mg quantities of antigen in complete Freund's adjuvant. A high volume ratio of adjuvant to antigen solution, and the volume used per inoculation, were shown to be critical factors. Ascitic fluids developed after three to five inoculations and were subsequently tapped repeatedly over a period of several weeks. All strains tested produced substantial amounts of anti-KLH antibodies, but marked differences were noted with respect to response to a hapten. Titers were enhanced in low responders by priming before the induction of ascites. The method is also useful for the production of "nonspecific" IgG and other serum components.

Animals↗
PubMedDate not supplied

Hypothesis: A recurrent, moderate activation fosters systemic autoimmunity--the apoptotic roles of TCR, IL-2 and Fas ligand.

Studies of several gene knockout mice suggest an interesting association of a moderate T cell response with systemic autoimmune diseases. In addition, CD95 ligand (FasL) expression in some strains of these mice is impaired. Because FasL is critically involved in regulating peripheral tolerance, there may be a link between autoimmune diseases and a moderate T cell response that cannot activate the FasL gene. Here, we propose that there are two thresholds of T cell activation. When moderately stimulated, T cells can be activated to the low (1st) threshold, which permits the induction of CD40L, IL-2, IL-4, and other components that help the immune response. The high (2nd) activation threshold can only be achieved by a strong and concurrent stimulation through TCR and IL-2R. Once the high threshold is reached, FasL is produced to induce apoptosis of the activated T and B cells. In the absence of the FasL-mediated downregulation, the activated B cells become efficient antigen-presenting cells for self-antigens and excellent responders for T cell help. Such an exacerbating condition, induced by recurrent and moderate activation, favors the development of autoreactive T cells and autoantibody production. Evidence supporting this hypothesis and some predictions that can be tested are described.

Animals↗
PubMedDate not supplied

Interrelationships among distinct idiotypic specificities.

The fine idiotypic properties of a hybridoma (H51.85.2) anti-GAT antibody which lacks both CGAT and GA-1 idiotypes are described. We identified another idiotype, termed GA-2 idiotype, on H51.85.2 hybridoma antibody. The GA-2 idiotype is present in all mouse strains tested and is induced by GA-related antigenic determinants. An interesting relationship between GA-1 and GA-2 idiotype on hybridoma anti-GA antibodies was observed. All GA-1+ hybridomas also express GA-2 idiotype. In contrast, GA-2+ hybridomas can express a full set, a fraction, or none of the GA-1 idiotypic determinants. The data together with previous amino acid sequence studies strongly suggest that H51.85.2 hybridoma antibody was derived from the same VH and VL genes encoding the GA-1+ hybridoma antibodies.

Amino Acid Sequence↗