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R A Insel

Publications and source records attributed to R A Insel.

At least 55 records · Page 3Linked to original sources
PubMed1988

Prospects for overcoming maturational and genetic barriers to the human antibody response to the capsular polysaccharide of Haemophilus influenzae type b.

The isolated capsular polysaccharide induces antibody protective against invasive infections by H. influenzae b. Maturation of responsiveness is slow such that infants are not protected. Several protein-coupled versions of the antigen are being tested for immunogenicity in early infancy. The relation of structure to immunogenicity is not completely defined, but all induce a booster-type antibody response with protective potential. Primary vaccination in infancy appears to mimic natural priming, activating clones of B lymphocytes that can later be restimulated by uncoupled polysaccharide. Prospects appear good for immunizing normal infants and also children with immunoregulatory defects predisposing to infection.

Age Factors↗
PubMed1987

In vitro human antibody production to the Haemophilus influenzae type b capsular polysaccharide.

In vitro production of human antibody to the Haemophilus influenzae type b capsular polysaccharide (PRP) and to tetanus toxoid (TT) and diphtheria toxoid was measured in culture supernatants of peripheral blood mononuclear cells and by enumeration of antibody secreting cells (AbSC) in an enzyme-linked immunosorbent-plaquing assay. Normal adult peripheral blood mononuclear cells stimulated with Epstein-Barr virus secreted anti-PRP antibody with a frequency of 1/552 to 1/1190 relative to total Ig secreting cells; the frequency of AbSC to tetanus toxoid (TT) was 7.5 times higher (p less than 0.05). These frequencies did not change significantly after in vivo immunization, although the isotype distribution shifted toward increased IgG for TT and increased IgG and IgA for PRP. At 8 days postimmunization, spontaneous AbSC to PRP and TT were detected; frequencies for total anti-TT AbSC again being higher than anti-PRP, but there were significantly more IgA plaques among anti-PRP AbSC. Spontaneous AbSC were suppressed in culture by pokeweed mitogen and enhanced by cyclosporine. Three wk after in vivo immunization with PRP and TT, in vitro stimulation with pokeweed mitogen, Staphylococcus aureus Cowan 1 bacteria, or antigen induced anti-TT but not anti-PRP in vitro antibody secretion, although Epstein-Barr virus induced both. These data suggest that PRP, a polysaccharide, and TT, a protein, differ in their requirements for in vitro activation with antigen and mitogens.

Antibody Formation↗
PubMed1987

Immunochemical variables affecting radioantigen-binding assays of antibody to Haemophilus influenzae type b capsular polysaccharide in childrens' sera.

In radioantigen-binding assays for antibody to Haemophilus influenzae type b capsular polysaccharide, an apparent antibody concentration [( (["Ab"]) is assigned to test sera on the basis of binding equivalence to dilutions of standard adult antiserum. In childrens' sera, ["Ab"] can disagree between laboratories and between intralaboratory assays using different preparations of radioantigen. Immunochemical variables causing disagreement include the dilution of test serum at which ["Ab"] is assigned and the concentration and size distribution of radioantigen. Binding-dilution curves of many childrens' sera displayed shallower slopes than did the standard, thus ["Ab"] increased with dilution, particularly in low-binding sera. An increase in radioantigen concentration also raised ["Ab"]. Using larger-sized radioantigen raised the binding in standard and childrens' sera comparably and thus would not directly affect ["Ab"] but would raise ["Ab"] indirectly by increasing the serum dilution. These results are theoretically predicted if the affinity of childrens' antibodies are lower than that of the standard.

Antibodies, Bacterial↗
PubMed1986

Vaccines consisting of periodate-cleaved oligosaccharides from the capsule of Haemophilus influenzae type b coupled to a protein carrier: structural and temporal requirements for priming in the human infant.

Reducing oligosaccharides from the Haemophilus influenzae type b capsular polymer (PRP) coupled by reductive amination to diphtheria toxoids (DTd) had been shown to elicit potentially protective serum anti-PRP antibodies (Ab) in infants too young for an adequate response to PRP vaccine. Here we report that cleavage of PRP with periodate gives antigenic oligosaccharides that couple with high efficiency. DTd-coupled saccharides of mean length eight or 20 repeat units (Dpo8 and Dpo20, respectively) were tested for immunogenicity in young adults (single injection) and in infants 9 to 15 mo old who received a sequence of primary (1 degree) and secondary (2 degrees) injections. Both vaccines consistently induced high anti-PRP Ab responses in adults. In infants, Dpo8 elicited only modest anti-PRP responses, whereas Dpo20 gave consistently high titers; post-2 degrees responses were higher when the interval between 1 degree and 2 degrees injections was 6 to 14 wk than with an interval of 2 to 4 wk. Thus with this type of immunogen, priming responses in infancy has more stringent structural requirements than does triggering responses in adults, and the priming appears to maximize more slowly than the Ab level.

Adult↗
PubMed1986

Oligosaccharide-protein conjugate vaccines induce and prime for oligoclonal IgG antibody responses to the Haemophilus influenzae b capsular polysaccharide in human infants.

The diversity of the IgG antibody induced by immunization of human infants and children with conjugate vaccines, composed of oligosaccharides prepared from the Haemophilus influenzae b capsular polysaccharide (CP) and covalently linked to diphtheria toxoids, was studied by analytical IEF. The antibody response was similar, in the degree of restriction, to that observed in the antibody response of older children to immunization with the CP alone. The booster responses induced by reimmunization with conjugate vaccines were accompanied by increases predominantly in the IgG antibody clonotypes expressed after the priming dose of vaccine. After a series of conjugate immunizations, immunization with isolated CP boosted the antibody titer and increased expression from all the clonotypes that were expressed after conjugate immunization. These findings suggest that the conjugate vaccines are acting on a limited number of human B cell clones that are preferentially restimulated after reimmunization. Little evidence of antigen-specific B cell recruitment was found. In addition, the ability of isolated CP immunization to restimulate the same B cell clone indicates that the responding B cell has matured and suggests a linear rather than a dual developmental pathway for the B cell participating in this human antibody response.

Age Factors↗
PubMed1985

Immunization of 2-month-old infants with protein-coupled oligosaccharides derived from the capsule of Haemophilus influenzae type b.

We studied an immunogen consisting of oligosaccharides derived from Haemophilus influenzae type b capsular polysaccharide (PRP) coupled to CRM197, a nontoxic relative of diphtheria toxin. Subcutaneous injections were given to eight subjects at ages 2, 4, and 6 months, simultaneously with conventional diphtheria-tetanus-pertussis (DTP) vaccine. After the first immunization, total serum anti-PRP antibodies declined in all subjects, but increased in most after the second immunization and after the third in seven of seven subjects analyzed. In these seven infants, the geometric mean level at age 9 months (0.73 micrograms/ml) exceeded by at least 40 times the means of historical control groups given DTP only or DTP plus (uncoupled) PRP vaccine. An isotype-specific assay showed that IgM antibodies increased after the first immunization with the coupled vaccine in all eight infants. Against the background of declining maternal IgG antibody, elevations in IgG antibody were detected after the second or third immunization in six of the eight. These six at age 9 to 11 months were immunized with (uncoupled) PRP vaccine, and a "boost" in anti-PRP antibody, including an IgG component, was found.

Antibodies, Bacterial↗
PubMed1985

Immunogens consisting of oligosaccharides from the capsule of Haemophilus influenzae type b coupled to diphtheria toxoid or the toxin protein CRM197.

Haemophilus influenzae type b (Hib) capsular polysaccharide (PRP) was selectively hydrolyzed to reducing oligosaccharides, and the fraction containing 3-10 ribosylribitolphosphate repeating units (VS) was conjugated by reductive amination to diphtheria toxin (DTx), its nontoxic derivative CRM197 (Dcr), or diphtheria toxoid (DTd). Conjugate DTx-VS retained approximately 1% of native toxicity, which was eliminated by treatment with formalin. Immunization of rabbits with the conjugates elicited antibody (Ab) to PRP and to DTx but not to a model for the linkage determinant. Human adults given single subcutaneous injections had rises in serum Ab to PRP and in bactericidal activity in vitro; the Ab protected infant rats challenged with Hib. Adults had rises also in Ab to DTd, and these Ab protected rabbits against DTx. A series of two injections of the conjugates Dcr-VS and DTd-VS was tested in infants beginning at 19-23 mo of age. Rises in anti-PRP Ab after the primary resembled the rises after PRP vaccine. In contrast to PRP, the conjugates elicited large rises after the secondary vaccinations and a substantial IgG component. Development of bactericidal activity paralleled the rises in anti-PRP Ab. Secondary rises after Dcr-VS were higher than after DTd-VS. In infants 12-16 mo of age, Dcr-VS (but not DTd-VS) elicited strong primary and secondary Ab responses that included IgG and bactericidal activity. Both conjugates produced consistent rises in Ab to DTd.

Adult↗
PubMed1985

Isoelectric focusing of human antibody to the Haemophilus influenzae b capsular polysaccharide: restricted and identical spectrotypes in adults.

Serum antibody to the capsular polysaccharide of Haemophilus influenzae b of human adults was analyzed by isoelectric focusing. Restricted antibody spectrotype patterns were commonly observed with as few as one spectrotype in some subjects after immunization with the isolated capsular polysaccharide. Some patterns were as restricted as human hybridoma antibody. There was no correlation of antibody titer and heterogeneity of patterns. The dominant spectrotype persisted unchanged for over 2 yr after immunization, and the pattern detected in preimmunization serum samples persisted unchanged after immunization. Indistinguishable patterns were commonly observed in genetically unrelated adults. Adults immunized with conjugate vaccines, which were composed of oligosaccharides prepared from the capsular polysaccharide that were covalently linked to protein carriers, also produced restricted serum antibody spectrotype patterns. Immunization with the cross-reactive polysaccharide of E. coli K100 induced a spectrotype pattern that was restricted but different from that induced by the H. influenzae b capsular polysaccharide.

Adult↗
PubMed1984

Reproducible production of protective human monoclonal antibodies by fusion of peripheral blood lymphocytes with a mouse myeloma cell line.

The production of monoclonal antibodies of human origin may represent a significant advance in immunotherapy for disease in humans. Although human monoclonal antibody has been produced from human lymphocytes by fusion with human myeloma cell lines or by Epstein-Barr viral transformation, fusion of postimmunization human lymphocytes with a mouse myeloma cell line is a relatively simple and reproducible alternative. Mouse-human hybrid cell lines were obtained in 205 (53%) of the microtiter wells initially seeded. Thirty-one (15%) of these hybrid cell lines secreted antibody of predefined specificity. Cloning was attempted with eight of the hybrid cell lines, and long-term antibody production was established in four of the lines: two hybridomas secreted antibody to the capsule of Haemophilus influenzae type b, one secreted antibody to tetanus toxoid, and one secreted antibody to diphtheria toxin. The production of mouse-human hybridomas appears to be a reliable method for obtaining human monoclonal antibody of predefined specificity.

Animals↗