Comparison of pneumococcal conjugate polysaccharide and free polysaccharide vaccines in elderly adults: conjugate vaccine elicits improved antibacterial immune responses and immunological memory.

BACKGROUND: High functional antibody responses, establishment of immunologic memory, and unambiguous efficacy in infants suggest that an initial dose of conjugated pneumococcal polysaccharide (PnC) vaccine may be of value in a comprehensive adult immunization strategy. METHODS: We compared the immunogenicity and safety of 7-valent PnC vaccine (7vPnC) with that of 23-valent pneumococcal polysaccharide vaccine (PPV) in adults >/=70 years of age who had not been previously vaccinated with a pneumococcal vaccine. One year later, 7vPnC recipients received a booster dose of either 7vPnC (the 7vPnC/7vPnC group) or PPV (the 7vPnC/PPV group), and PPV recipients received a booster dose of 7vPnC (the PPV/7vPnC group). Immune responses were compared for each of the 7 serotypes common to both vaccines. RESULTS: Antipolysaccharide enzyme-linked immunosorbent assay antibody concentrations and opsonophagocytic assay titers to the initial dose of 7vPnC were significantly greater than those to the initial dose of PPV for 6 and 5 of 7 serotypes, respectively (P < .01 and P < .05, respectively). 7vPnC/7vPnC induced antibody responses that were similar to those after the first 7vPnC inoculation, and 7vPnC/PPV induced antibody responses that were similar to or greater than antibody responses after administration of PPV alone; PPV/7vPnC induced significantly lower antibacterial responses, compared with those induced by 7vPnC alone, for all serotypes (P < .05). CONCLUSION: In adults, an initial dose of 7vPnC is likely to elicit higher and potentially more effective levels of antipneumococcal antibodies than is PPV. In contrast with PPV, for which the induction of hyporesponsiveness was observed when used as a priming dose, 7vPnC elicits an immunological state that permits subsequent administration of 7vPnC or PPV to maintain functional antipolysaccharide antibody levels.

Correlation of the Km(1) immunoglobulin allotype with anti-polysaccharide antibodies in Caucasian adults.

Km allotype antigens are serologic markers expressed on kappa light chains of human immunoglobulins. To determine whether th Km phenotype of an individual is related to his ability to make antibodies to polysaccharide antigens, we correlated the Km allotypes of 129 healthy caucasian adults with the concentrations of specific antibodies to three bacterial polysaccharide antigens after immunization. The 14 individuals expressing the Km(1) allotype had lower concentrations of IgG, IgM, and IgA antibodies by enzyme-linked immunosorbent assay and total antibody by radioimmunoassay to Haemophilus influenzae type b and Neisseria meningitidis group C capsular polysaccharides when compared with the 115 Km(1) negative individuals. The Km-associated differences in H. influenzae type b and N. meningitidis group C antibody concentrations were confined to kappa light chain-containing antibody (P = 0.029 and 0.003, respectively). Similarly, the Km(1) positives had slightly lower kappa chain-containing Ig than the Km(1) negatives (P = 0.079). We conclude that genes in or near the kappa light chain locus play a role in the regulation of kappa-containing antibody production to some bacterial polysaccharides and perhaps to other antigens.

Correlation between G2m(n) immunoglobulin allotype and human antibody response and susceptibility to polysaccharide encapsulated bacteria.

To determine whether genetic factors influence the human antibody response to polysaccharides, we correlated Ig allotypes with the concentrations of antibody to 14 bacterial capsular antigens in 130 actively immunized Caucasian adults. The 88 individuals possessing G2m(n), an allotype antigen of IgG2 subclass heavy chains, had significantly higher postimmunization antibody levels to Haemophilus influenzae type b (Hib) and 8 of 11 pneumococcal types (P less than 0.05) than the 42 lacking this antigen. For Hib, pneumococcus type 14, and meningococcus group C, an increased response was observed in IgG class but not in IgM or IgA classes of antibody. The G2m(n) positive individuals also had higher preimmunization antibody levels to most polysaccharide antigens. Total IgG2 concentrations were correlated with the mean postimmunization antibody concentrations to pneumococci (P = 0.005), but this correlation was independent of G2m(n) by multiple regression analysis. To determine if the lack of G2m(n) was associated with increased susceptibility to infection, we compared the frequencies of various Ig allotypes in 98 children infected with Hib and 98 matched controls. Caucasian children with Hib infections other than epiglottitis were significantly more likely to lack the G2m(n) allotype than controls (P less than 0.05). G2m(n) negative Caucasian children less than or equal to 18 mo old have a 5.1-fold higher risk of nonepiglottitic Hib infections than G2m(n) positive children (P less than 0.01). We conclude that allotypic variants of the gamma-2 heavy chain genes, or genes in linkage equilibrium with them, exert a regulatory influence on the caucasian antibody response to a variety of immunologically distinct bacterial polysaccharide antigens. Young Caucasian children of the low responder phenotype, i.e., those lacking the G2m(n) allotype, are genetically predisposed to Hib and perhaps other bacterial infections.

Increased gastrointestinal absorption of large molecules in patients after 5-fluorouracil therapy for metastatic colon carcinoma.

Chemotherapeutic agents may damage gastrointestinal epithelium and thereby impair the mucosal barrier to bacteria and their products. In order to obtain an objective measurement of gastrointestinal permeability to large molecules, we measured urinary excretion of [14C]polyvinylpyrrolidone administered p.o. (mean molecular weight 11,000) and tobramycin (molecular weight 467) in ten patients receiving 5-fluorouracil therapy for metastatic cancer of the colon. Base-line absorption of [14C]polyvinylpyrrolidone was 0.013 to 0.048% of the administered dose. Dose-related increases in absorption (range, two to 20 fold) occurred after 5-fluorouracil administration, but the dose response differed markedly between individuals. Absorption was maximal 8 to 15 days after the start of therapy, was correlated in time but not necessarily in severity with the presence of gastrointestinal symptoms, and was unaffected by oral nonabsorbable antibiotics. Tobramycin excretion was 8.5 times greater than [14C]polyvinylpyrrolidone excretion, but the two were highly correlated in simultaneous determinations (r, 0.93; p, < 0.001). With the exception of an episode of Escherichia coli bacteremia, infections coincided not with maximal [14C]polyvinylpyrrolidone absorption but with maximal granulocytopenia 17 to 24 days after the start of therapy. The gastrointestinal absorption of polyvinylpyrrolidone provides an objective measurement of mucosal integrity which may have applications in assessing the gastrointestinal toxicity of other cytotoxic agents.

Method for quantitation of IgG subclass antibodies in mouse serum by enzyme-linked immunosorbent assay.

One of the methods for calibration of antigen specific antibodies in a serum involves parallel titration of known concentrations of purified normal immunoglobulins (Igs) and a specific antiserum. We evaluated the effect of three methods for capturing known concentrations of purified normal mouse Igs (IgG, IgG subclasses and IgM) on the anti-tetanus toxoid antibody concentrations assigned to a reference mouse serum: (1) direct coating, (2) capture by pre-coated anti-mouse IgG (Fc) specific antibodies, and (3) capture by pre-coated anti-mouse IgG (Fab) specific antibodies. Direct coating of purified Igs onto plastic was the least efficient and would greatly overestimate antigen specific antibody concentrations. Equivalent concentrations of purified IgG subclasses and IgM produced higher absorbances when captured by anti-Fab antibodies pre-coated on plates than by anti-Fc antibodies. As a consequence, the anti-Fc capture method resulted in the assignment of IgG1, IgG2a and IgG2b tetanus specific antibody concentrations which exceeded the total IgG1, IgG2a and IgG2b concentrations. Additionally, the sum of tetanus specific IgG subclass antibodies exceeded the tetanus specific IgG antibody concentration by > 2-fold. In contrast, the anti-Fab capture method resulted in 2-9-fold lower assigned tetanus antibody concentrations which did not exceed the total Ig concentrations. We conclude that when using enzyme-linked immunosorbent assays, parallel titration of purified normal Ig standards captured by anti-Fab antibodies is superior to anti-Fc capture or direct coating for calibrating antigen specific antibodies in a reference serum.

Evaluation of a commercial latex particle agglutination test for rapid diagnosis of Haemophilus influenzae type b infection.

The effectiveness of a commercially available latex particle agglutination test (Bactogen) in the diagnosis of invasive Haemophilus influenzae type b infection was evaluated. Bactogen correctly diagnosed all 27 patients with bacteriologically proven H influenzae type b infection (sensitivity 100%). Two of 39 patients with proven, non-H influenzae type b infections had false-positive tests (specificity 95%). One of 103 sera and 0 of 55 urine specimens from hospitalized adults contained detectable H influenzae type b antigen. Bactogen is a sensitive, specific, commercially available test for rapid diagnosis of H influenzae type b infection.

Antibody response of Navajo children primed with PRP-OMP vaccine to booster doses of PRP-OMP vs. HbOC vaccine.

We compared in 12- to 15-month-old American Indian infants the safety and immunogenicity of two licensed Haemophilus influenzae type b (Hib) conjugate vaccines, PRP-OMP (PedvaxHib) and HbOC (HibTITER), administered as booster vaccinations. All infants previously received PRP-OMP for their primary Hib vaccinations at 2 and 4 months of age. The geometric mean Hib antibody concentrations (microgram/ml) measured by radioactive antigen-binding assay for those receiving PRP-OMP (n = 17) or HbOC (n = 18) were 0.593 and 0.449, respectively, before boosting (P not significant) and 7.46 and 29.5 micrograms/ml, respectively, after boosting (P < 0.05). PRP-OMP recipients also had lower geometric mean IgG anti-Hib antibody concentrations than HbOC recipients (7.21 vs 28 micrograms/ml, P = 0.003) and lower bactericidal titers (3.18 vs. 15.4, not significant). We conclude that HbOC vaccine produced a significantly greater booster response than PRP-OMP vaccine when given at 12 to 15 months of age to children primed with two doses of PRP-OMP vaccine at 2 and 4 months of age.

Haemophilus influenzae type b-specific antibody in infants after maternal immunization.

OBJECTIVE: To study the kinetics of Haemophilus influenzae type b (Hib)-specific antibody in infants born to mothers immunized with an Hib polysaccharide or one of two Hib conjugate vaccines. STUDY DESIGN: Serum antibody to the polyribosylribitol (PRP) moiety of Hib was measured by radioimmunoassay and enzyme-linked immunosorbent assay at birth and at 2 and 6 months of age in infants born to women immunized with Hib polysaccharide or conjugate vaccine (PRP-D and HbOC). A subset of infants > or = 6 months of age was immunized with Hib conjugate vaccine after licensure of this vaccine for infants. A comparison group of 18 infants born to unimmunized women received the same Hib conjugate vaccine on a similar schedule. RESULTS: Total PRP antibody concentrations were 1.50, 14.4 and 20.4 microg/ml in 2-month-old infants born to mothers immunized with polysaccharide, PRP-D and HbOC vaccines, respectively, and 2.54, 1.35 and 2.46 microg/ml in 6-month-old infants. Infants born to mothers immunized with polysaccharide vaccine had significantly less PRP antibody at 2 months of age but similar antibody concentrations at 6 months of age. Persistence or increases in total PRP antibody during 6 months were noted in 21 of 47 (44.6%) study infants. A subset of study and comparison infants was immunized with a mean of 2.6 doses of Hib vaccines between 6 months and 2 years of age, and all infants had total PRP antibody concentrations > or = 0.15 microg/ml. CONCLUSION: Conjugate Hib vaccines administered during the last trimester of pregnancy resulted in significantly higher PRP antibody titers in infants at birth and 2 months of age than did polysaccharide vaccine. A subset of infants born to immunized mothers was subsequently immunized with Hib conjugate vaccine and had antibody concentrations similar to those in infants born to nonimmunized women.

Treatment of severe pertussis: a study of the safety and pharmacology of intravenous pertussis immunoglobulin.

BACKGROUND: Pertussis in infants is often severe, resulting in complications and prolonged hospitalization. Treatment is limited to supportive care. Antibiotics do not significantly alter the course of the disease. Therapies directed at pertussis toxin, a major virulence factor of Bordetella pertussis, might be beneficial. This study examines the safety and pharmacology of intravenous pertussis immunoglobulin (P-IGIV), which has high levels of pertussis toxin antibodies. METHODS: P-IGIV was prepared as a 4% IgG solution from the pooled plasma from donors immunized with inactivated pertussis toxoid. The IgG pertussis toxin antibody concentration of 733 microg/ml is >7-fold higher than contained in conventional intravenous immunoglobulin products. Children with presumptive pertussis were allocated to one of three treatment doses of P-IGIV. RESULTS: Twenty-six of 30 enrolled children had confirmed pertussis. There were no adverse events associated with P-IGIV except one patient who had transient hypotension that responded to an infusion rate decrease. P-IGIV doses of 1500, 750 and 250 mg/kg achieved > or =4-fold, 3-fold and >2-fold rises in peak geometric mean titers of pertussis toxin IgG antibodies, respectively. P-IGIV exhibited a half-life of 38.4 days and a volume of distribution of 87.8 ml/kg. All three treatment groups showed declines in lymphocytosis (P < 0.05) and paroxysmal coughing by the third day after P-IGIV infusion compared with preinfusion values. CONCLUSION: P-IGIV is safe and achieves high pertussis toxin antibody titers in infants. This study provides data for a prospective, controlled trial of P-IGIV.

Decline of Haemophilus influenzae type b disease in a region of high risk: impact of passive and active immunization.

Haemophilus influenzae type b (Hib) is a major cause of serious childhood bacterial infections. Before 1989 Alaska Native infants in the Yukon Kuskokwim Delta (YKD) had the highest recorded Hib disease rate, 2960:100,000 in children less than 1 year of age with 6 to 35 (mean, 13) cases/year between 1980 and 1988. In July, 1989, Alaska Area Native Health Service initiated a passive immunization project in the YKD using bacterial polysaccharide immunoglobulin (BPIG) administered at 3-month intervals to prevent Hib infections in infants less than 13 months of age. On January 1, 1991, after licensure of Hib conjugate vaccines for infants, the program was modified to a passive-active strategy using BPIG at birth and PedvaxHIB at 2, 4 and 12 months of age. Between July 1, 1989, and December 31, 1990, 80% of YKD children less than 1 year of age received at least 1 dose of BPIG. During this period there were 7 Hib cases in this age group, but only 1 of the cases had received any BPIG. Between January 1, 1991, and December 31, 1992, 4 Hib cases occurred in 2 YKD children. During the combined period, July 1, 1989, to December 31, 1992, the incidence of Hib disease for infants less than 1 year of age was 302:100,000. A dramatic decrease in Hib disease was observed in this high incidence region concurrent with implementation of passive and passive-active immunization strategies.

Safety and antibody persistence following Haemophilus influenzae type b conjugate or pneumococcal polysaccharide vaccines given before pregnancy in women of childbearing age and their infants.

BACKGROUND: Immunization of healthy women before pregnancy is a potential approach to providing increased levels of maternal antibody to newborns to protect them from infections occurring during the perinatal period and first months of life. METHODS: Healthy nonpregnant Pima Indian women of childbearing age were randomized to receive one of two Haemophilus influenzae type b (Hib) conjugate vaccines [HbOC or Hib-meningococcal outer membrane protein complex (OMP)] or a 23-valent pneumococcal polysaccharide vaccine (PnPs). Infants received Hib-OMP vaccine at 2, 4 and 12 months of age. Vaccine safety and immunogenicity was evaluated in the women and their infants. RESULTS: Anti-polyribose ribitol phosphate antibody titers were significantly higher in women in both Hib conjugate vaccine groups than in the pneumococcal vaccine group throughout the 37-month observation period. Antibody responses to HbOC vaccine were significantly higher than those to Hib-OMP. A subsequent booster dose of each Hib conjugate vaccine induced reactions and antibody responses similar to those of the first dose. Infants born to mothers immunized with Hib vaccines compared with PnPs had significantly higher polyribose ribitol phosphate-specific IgG antibody titers at birth and 2 months of age but lower antibody responses to Hib-OMP at 6 months and similar titers before and after boosting with Hib-OMP at 1 year of age. By contrast women immunized with PnPs did not have significantly elevated concentrations of pneumococcal-specific antibody at delivery, and their infants had pneumococcal antibody titers similar to those of infants born to mothers who did not receive pneumococcal vaccine before pregnancy. CONCLUSION: Hib conjugate vaccine given to women before pregnancy significantly increased the proportion of infants who had protective Hib antibody levels at birth and 2 months of age.

Immunotherapy of respiratory syncytial virus pneumonia following bone marrow transplantation.

Respiratory syncytial virus (RSV) pneumonia is a well-recognized complication of bone marrow transplantation with a high mortality rate. We describe two patients who developed RSV pneumonia within the first 3 weeks following allogeneic bone marrow transplantation. These patients had significant oxygen requirements and radiographic infiltrates. Both were treated with aerosolized ribavirin and given a single 1.5 gm/kg dose of intravenous immune globulin containing high levels of RSV neutralizing activity (RSV-IG). Both patients showed subjective and objective improvement after RSV-IG, never required mechanical ventilation, and were discharged without an oxygen requirement within 2 weeks after therapy. RSV microneutralization activity was measured in serum and nasal secretions. Mean serum microneutralization activity increased from 2279 microneutralization units (Mu)/ml to 18082 Mu/ml after RSV-IG. Peak serum microneutralization activity achieved with RSV-IG was higher than that achieved in a series of other immunocompromised adults with RSV pneumonia given either multiple doses of standard IVIG or no immune globulin therapy. RSV-IG may be beneficial in the treatment of RSV pneumonia in severely immunocompromised patients.

Phycomycotic gangrenous cellulitis. A report of two cases and a review of the literature.

Progressive gangrenous cellulitis due to Rhizopus arrhizus following colostomy destroyed the entire abdominal wall of a young woman and caused her death. A similar infection in an 11-year-old kidney transplant recipient was diagnosed more promptly and treated successfully with extensive debridement and amphotericin B. Nine similar cases found in the literature were reviewed. All 11 patients appeared to have had prior tissue injury at the original site of infection, and seven had diabetes mellitus. The disease was initially misdiagnosed in most of the patients, progressed rapidly in eight, and was fatal in four. Phycomycotic gangrenous cellulitis should be included in the differential diagnosis of progressive necrotizing lesions of the skin, especially in diabetic patients, but it can be identified promptly only by histologic examination of the infected tissue. Urgent radical excision and amphotericin therapy are recommended.

Production of cell mass and pertussis toxin by Bordetella pertussis.

The cultivation of Bordetella pertussis affects production of pertussis toxin and biomass. Comparison of batch mode, chemostat operation and pHstat-turbidostatic control showed that productivities for the continuous process were greater than that for the batch operation. Continuous operation in balanced growth at the maximum specific growth rate, provided by the pHstat, resulted in the maximum specific production rate. Because of the strong association of pertussis toxin synthesis and cell growth, the concentration of toxin in the effluent of the continuous processes was greater than the maximum obtained in the batch bioprocess. An expanded Luedeking-Piret model of product formation kinetics fits the observed chemostat data and demonstrates that the production of pertussis toxin from the culture of B. pertussis is predominantly growth associated.

Improved pertussis toxin production by Bordetella pertussis through adjusting the growth medium's ionic composition.

Ionic composition and total ionic concentration of the growth medium were important factors in limiting productivities in aerated reactors used for the production of pertussis toxin and other antigens by Bordetella pertussis. Salt concentration has opposing effects on cell growth of wild-type B. pertussis and specific toxin formation. Sodium ion concentrations below 140 mM correlated with a precipitous decline in specific yields of pertussis toxin, an otherwise growth-associated product. High salt concentrations in the medium resulted in lower final cell concentrations but did not affect initial growth rates. A new medium is proposed that allows a 60 to 70% increase in both cell and toxin yields by replacing the sodium chloride in the 'cyclodextrin liquid' (CL) medium with additional monosodium glutamate which provides both the sodium and the carbon and energy source.

Formation and cell-medium partitioning of autoinhibitory free fatty acids and cyclodextrin's effect in the cultivation of Bordetella pertussis.

Palmitic, palmitoleic and stearic acids were found in the extracted cellular lipids of virulent Bordetella pertussis as unesterified acids in confirmation of earlier taxonomic analyses. The same free fatty acids (FFAs) were found in the spent culture supernatant in concentrations higher than in the uninoculated medium, indicating that they are released into the extracellular medium. These long-chain fatty acids are known to inhibit the growth of B. pertussis at concentrations as low as 1 ppm. Measurement of palmitate cell-medium partitioning demonstrated a strong tendency of FFAs for cellular adsorption. Inhibition kinetics indicated that the cell-bound FFA was responsible for inhibition and that the specific cellular FFA concentrations actually found during growth were similar to those determined to be inhibitory. Autoinhibition by these endogenous FFAs provides an explanation of the low maximum cell concentrations currently attainable in liquid media. Addition of soluble dimethyl-beta-cyclodextrin (MebetaCD) to FFA-inhibited cultures resulted in a rapid reversal of the inhibition. A corresponding shift in the distribution of FFAs from the cells to the extracellular medium demonstrated that MebetaCD sequesters FFAs. Although MebetaCD did not increase final cell concentrations and even had an adverse effect on growth at concentrations above 1 g l-1, it did (at 1 g l-1 extend the initial period of high growth rate leading to shorter cultivation times.

Pulsed controlled-released system for potential use in vaccine delivery.

Biodegradable polymeric devices intended to provide a viable route for single-dose vaccination were developed using controlled-release technology. One of the main challenges in the development of these devices was to overcome several water-mediated inactivation processes that occur in conventional polymeric systems. Our strategy was focused on the prevention of antigen exposure to environmental conditions. For this purpose a microencapsulation process was designed and optimized to provide an inert and insulated environment for the bioactive material inside controlled-release systems. Tetanus toxoid (TT) was used as a model antigen. The systems consist of core-wall microcapsule structures in which the antigenic protein is entrapped into oil-based cores of TT surrounded by outer polymer shells made of poly(D,L-lactide-co-glycolide), thus potentially protecting the bioactive material against deleterious conditions. Furthermore, using these microcapsules, pulses of immunochemically detected TT were programmed to release at two different times (3 and 7 weeks), as corroborated by in vitro release studies. The engineering of these specific antigen release properties was possible by careful selection of the copolymer composition and molecular weight. The final formulations were characterized with respect to morphology, structure, size distribution, and amount of immunochemically detected TT encapsulated. The new systems offer the potential to control the manner and timing of delivery. Over 92% of the TT released over a 63 day period from these microcapsules was immunochemically detected.