Sex hormones and the immune response. II. Perturbation of antibody production by estradiol 17beta

The administration of 75 microgram/kg of estradiol 17beta at successively later stages in the immune response of female guinea pigs to penicilloyl-coupled cavian globulins showed that this steroid reduces the rate of attainment of the maximum titer, the magnitude of the titer achieved, and the rate of titer decay. Control titers maximized at the third experimental week and diminished to one third the peak value by the 6th week. When steroid treatment was begun coincidentally with inoculation (week 0), the peak titer was delayed by 3 weeks, and by 2 weeks when hormone priming was begun at week 1 or 2. The highest antibody titers achieved in the presence of estrogen were 25-30% lower than those of sesame oil controls. The greatest immunosuppressive effect was observed when estradiol was given at the peak of the immune response, the titer dropping by 50% and remaining at that level for the next 4 weeks in spite of continued antigen inoculation and steroid treatment. Titer decay after the end of the inoculation course was prevented by estradiol but not by progesterone, CHP, or these same oil vehicle.     

Simple method for development of sensitive and specific antiinsulin antisera for laboratory use

Commercial sources provide good, though expensive antiinsulin antisera. We describe here a simple, fast and inexpensive method for the production of antiinsulin antisera. Purified pork insulin (Lente) was injected subcutaneously in oil/water/complete Freund adjuvant mixture. Three guinea pigs received 0.25 mg of insulin and three received 0.5 mg of insulin. Subsequent injections of the same dose were done 40 and 60 days later. Five animals developed antisera with titers superior to 1:10,000 40 days after the primary inoculation. Four out of five guinea pigs improved further their antibody titer after the 2nd and 3rd injection (p less than 0.0005). Good sensitivity was associated with titers superior to 1:50,000 and appeared only after the 2nd injection to improve further after the 3rd. Thus, four out of six animals developed antiinsulin antisera suitable for the radioimmunoassay (RIA). The antisera bound proinsulin on an equimolar basis with insulin while glucagon was not bound up to 100 ng/ml. The minimum detectable insulin concentration was about 12 pg (0.3 microU) at the optimum antiserum dilution. Six animals given a small dose of insulin (0.06 mg) developed antisera of a low titer and sensitivity, unsuitable for the RIA.     

Simple Method for Development of Sensitive and Specific Antiinsulin Antisera for Laboratory Use

Commercial sources provide good, though expensive antiinsulin antisera. We describe here a simple, fast and inexpensive method for the production of antiinsulin antisera. Purified pork insulin (Lente) was injected subcutaneously in oil/water/complete Freund adjuvant mixture. Three guinea pigs received 0.25 mg of insulin and three received 0.5 mg of insulin. Subsequent injections of the same dose were done 40 and 60 days later. Five animals developped antisera with titers superior to 1:10,000 40 days after the primary inoculation. Four out of five guinea pigs improved further their antibody titer after the 2nd and 3rd injection (p < 0.0005). Good sensitivity was associated with titers superior to 1:50,000 and appeared only after the 2nd injection to improve further after the 3rd. Thus, four out of six animals developed antiinsulin antisera suitable for the radioimmunoassay (RIA). The antisera bound pro-insulin on an equimolar basis with insulin while glucagon was not bound up to 100 ng/ml. The minimum detectable insulin concentration was about 12 pg (0.3 μU) at the optimum antiserum dilution. Six animals given a small dose of insulin (0.06 mg) developed antisera of a low titer and sensitivity, unsuitable for the RIA.     

A time- and cost-saving method of producing rat polyclonal antibodies

Producing antibodies usually takes more than three months. In the present study, we introduce a faster way of producing polyclonal antibodies based on preparation of the recombinant oligopeptide as antigen followed by immunization of rats. Using this method, we produced antisera against two mouse proteins: ERGIC-53 and c-Kit. An expression vector ligated with a pair of complementary synthetic oligodeoxyribonucleotides encoding the protein was introduced into bacteria, and the recombinant oligopeptide fused with the carrier protein glutathione-S-transferase was purified. Wistar rats were immunized by injecting the emulsified antigen subcutaneously into the hind footpads, followed by a booster injection -after 2 weeks. One week after the booster, the sera were collected and examined for the antibody titer by immunohistochemistry. Antisera with 1600-fold titer at the maximum were obtained for both antigens and confirmed for their specificity by Western blotting. Anti--ERGIC-53 antisera recognized acinar cells in the sublingual gland, and anti-c-Kit antisera recognized spermatogenic and Leydig cells in the testis. These antisera were applicable to fluorescent double immunostaining with mouse monoclonal or rabbit polyclonal antibodies. Consequently, this method enabled us to produce specific rat polyclonal antisera available for immunohistochemistry in less than one month at a relatively low cost.     

Serological basis for use of meningococcal serogroup C conjugate vaccines in the United Kingdom: reevaluation of correlates of protection

The antibody data supporting the use of meningococcal serogroup C conjugate (MCC) vaccines in the United Kingdom were generated by serum bactericidal assay (SBA) using rabbit complement (rSBA). This may give higher titers than those obtained with human complement (hSBA), for which the "gold standard" correlate of protection for meningococcal C disease is a titer of > or =4. Comparison of rSBA and hSBA titers in sera from unvaccinated adults with an rSBA titer of > or =8 showed that for 93% (27 of 29) the titer was > or =4 by hSBA, confirming natural protection. Furthermore, sera from MCC vaccinees showed that an rSBA titer of <8 or > or =128 discriminated susceptibility and protection well (85% with rSBA titers of <8 had hSBA titers of <4, and 99% with rSBA titers of > or =128 had hSBA titers of > or =4). However, discrimination was poor in the rSBA titer range 8 to 64, with only 60% having hSBA titers of > or =4. In such cases we propose that protection can be assumed if there is a fourfold rise in titer between pre- and postvaccination sera or if there is a characteristic booster response to a polysaccharide challenge dose with, if available, evidence of antibody avidity maturation or an hSBA titer of result > or =4. Applying these criteria to toddlers, 10 to 40% of whom had titers in the range 8 to 64 after a single dose of MCC vaccine, showed that 94% had a fourfold rise in titer, including 98% of those in the titer range 8 to 64. In addition, of those with titers of <128 post-MCC vaccination, 90% had titers of > or =128 after a 10-microg polysaccharide booster dose, compared with only 7% of unprimed age-matched toddlers given a full 50-microg dose. Furthermore, the increase in geometric mean avidity index pre- and postbooster was independent of post-primary MCC titer. These results indicated that the majority of toddlers with an rSBA titer between 8 and 64, and some of those with an hSBA result of <4, have mounted a protective immune response with the induction of immunological memory.     

The immune response in immunized and naturally infected rainbow trout (Salmo gairdneri) to Diplostomum spathaceum as detected by enzyme-linked immunosorbent assay (ELISA)

The enzyme-linked immunosorbent assay (ELISA) procedure was modified and adapted for detection of circulating antibodies in rainbow trout (Salmo gairdneri) against metacercariae of the digenean trematode Diplostomum spathaceum, the causative agent for diplostomiasis. Rainbow trout (Salmo gairdneri) were injected with sonicated metacercariae representing 10, 40, and 100 metacercariae per fish. Three weeks after immunization the average titers for trout injected with 10, 40, and 100 metacercariae were 874, 841, and 525, and by six weeks the titers had fallen to 299, 349, and 203, respectively. Nine weeks after initial immunization, two remaining fish initially immunized with 100 metacercariae per fish were injected with a booster of 50 sonicated metacercariae per fish. Four weeks later the average titer was 1204. Serum samples from naturally infected wild fish tested for the presence of circulating antibodies against Diplostomum spathaceum showed 25 of 27 with positive titers.     

Sequential development of helper and suppressor functions, antibody titers and functional avidities to a streptococcal antigen in rhesus monkeys

Sequential development of antibody titer, functional avidity, helper and suppressor activities were investigated in rhesus monkeys. These were immunized with a single dose of 0.1 microgram to 10 mg of a streptococcal protein antigen (SA) in aluminium hydroxide. The IgG antibody titers followed the classical pattern first established in mice, of high-dose and low-dose tolerance with intermediate doses of immunity. This was correlated with a similar pattern of functional avidity of IgG antibodies, as measured by a dissociation assay. Helper and suppressor functions were assayed in parallel by inducing the corresponding factors from monkey lymphocytes in Marbrook flasks and testing the factors which cross the species barrier in cooperative cultures with CBA mouse spleen B cells. A progressive modulation of helper and suppressor activities was elicited by the increasing doses of SA, during the initial 28 days after immunization. Thus, dominant suppressor with minimal helper activity, IgG antibody titer and functional avidity were elicited by 0.1 microgram SA. However, 1 or 10 micrograms SA induced dominant helper with minimal or transient suppressor activity and high IgG antibody titers and functional avidity. Somewhat intermediate responses were elicited by 100 micrograms SA, but 1 mg and especially 10 mg SA induced dominant suppressor and minimal helper activity, with low IgG antibody titers and functional avidities. When the immune response was established, about 28 days after immunization, the intermediate dose of SA elicited IgG antibodies with high titer and functional avidity, high T cell helper but low suppressor activities. In contrast, both high- and low-dose SA induced partial tolerance, with low IgG antibody titer, functional avidity and T cell helper activity. These studies suggest cyclical development of helper and suppressor functions during the 4 weeks after immunization. The emergence of a dominant helper or suppressor function is antigen dose dependent.     

Antigenic characterization of intermediate adenovirus 14-11 strains associated with upper respiratory illness in a military camp.

An unusual variant of adenovirus (AV) 11 was isolated from throat and rectal swabs from six persons with upper respiratory illness in a Spanish military camp in March 1969. The same strain was serologically related to the upper respiratory illness of seven other men among 25 sample cases studied in detail. After strain purification, the virus was grouped as an AV by standard biological tests; it possessed the usual titers of group-specific hexon antigen but only low hemagglutinin titers (1:4 to 1:8) with erythrocytes from selected rhesus monkeys. The virus gave little reaction in hemagglutination inhibition (HI) tests with antisera to AV 1 through 35, but was neutralized to homologous titers by AV 11 antiserum. Reciprocally, rabbit and guinea pig antisera to the isolates possessed high HI antibody titers to prototype AV 14 and high serum neutralization (SN) antibody titers to prototype AV 11. On this basis, the variants were classified as AV 14-11 intermediates. Sequential serum specimens from the patients with and without positive cultures showed diagnostic rises in HI and SN antibody levels to the AV 14-11 intermediate and to prototype AV 11, but little response to AV 14.     

Benefits of increasing the dose of influenza vaccine in residents of long‐term care facilities: A randomized placebo‐controlled trial

Increased vaccine doses and mid‐season boosting may increase the proportion of residents with protective immunity from influenza in long‐term care facilities. In a multi‐center study (1997–1998), 815 residents from 14 long‐term care facilities were assigned at random to receive 15 or 30 µg of inactivated influenza vaccine, followed by a 15 µg booster vaccine or a placebo vaccine at Day 84. Seroresponses were re‐analyzed by hemagglutination‐inhibition (≥4‐fold titer increases, protective titer ≥40, geometric mean titers. Forty percent of the participants had pre‐vaccination titers ≥40. At Day 25 after vaccination, this increased to 66.3% after a 15 µg dose versus 73.3% after a dose of 30 µg (P = 0.049). Participants receiving a 30 µg dose followed by a 15 µg booster showed more ≥4‐fold titer increases at Day 109 (43.6% vs. 35.4%, P = 0.003) and protective titers ≥40 (74.2% vs. 64.6%, P = 0.041), compared to those receiving only a 15 µg dose. Differences were most apparent in participants with low pre‐vaccination titers. Booster vaccination after an initial 15 µg dose of the vaccine did not increase the protective rate (61.9% vs. 63.9% after placebo). The number of participants needed to vaccinate to protect one additional resident by a dose of 15 µg was 4, by a dose of 30 µg 3, and 15 when using a 30 µg dose instead of 15 µg. Doubling the dose of influenza vaccine increased protection‐related responses among residents of long‐term care facilities, especially in those with low pre‐vaccination titers. J. Med. Virol. 81:908–914, 2009. © 2009 Wiley‐Liss, Inc.     

Antigenic contraction of guinea pig tracheal preparations passively sensitized with monoclonal IgE: pharmacological modulation

Spirally cut guinea pig tracheal preparations were passively sensitized using a mouse monoclonal IgE antibody against dinitrophenol (DNP). Maximal contraction observed following challenge with DNP-bovine serum albumin (DNP-BSA, 5 micrograms/ml; n = 20) response was approximately 46% of the histamine response (0.52 +/- 0.09 g/mm2; n = 53). Indomethacin (1.7 microM) increased and PGE2 (1 microM) decreased the response to the antigen. FPL 55712 (10 microM), atropine (0.1 microM), L 651392 (5 microM) or tripelennamine (1 microM) always reduced the maximal DNP-BSA response, but not BN 52021 (100 microM). This model may be used for rapid detection of compounds with antiallergic properties on IgE-dependent lung pathological states.     

Immunological evidences for the presence of small late carboxylterminal fragment(s) of human parathyroid hormone (PTH) in circulation in man

Two antisera, C-52 and C-97, raised against bovine (b)PTH(1-84) in guinea pigs, were evaluated with 125I-[tyr53] human (h)PTH(53-84) as tracer and intact hPTH(1-84) and synthetic hPTH(39-84), representative of large carboxylterminal ("C") fragments found in circulation, as standards. In both assays, hPTH(39-84) was 5-6 times more potent than hPTH(1-84) on a molar basis in displacing the tracer. With both antisera, progressive deletion at the aminoterminal end of large "C" fragments, as in hPTH(53-84) and hPTH(65-84), lead to decreased immunoreactivity, hPTH(69-84) being non-immunoreactive. The mid-carboxylterminal fragments, hPTH(44-68) and hPTH(39-68), did not react in either assay. Each antiserum measured known quantities of pure hPTH(1-84) or hPTH(39-84) standards similarly. Serum PTH values obtained with antiserum C-97 were about 3 times higher in renal failure, 1.75 times higher in normal individuals and those with primary hyperparathyroidism, while similar to values measured with antiserum C-52 in individuals with secondary hyperparathyroidism without renal failure or with pseudohypoparathyroidism. When circulating PTH taken from patients with these disorders was fractionated by gel chromatography, both antisera recognized similar peaks of intact hPTH(1-84) and of large "C" fragments while antiserum C-97 further recognized a peak of smaller "C" fragments. This explained the different clinical behavior of the latter antiserum. Our findings demonstrate the existence of small late "C" fragments in circulation. They further suggest an influence of serum calcium and of renal function on the quantity of these fragments.     

German experimental hepatitis B vaccine — Influence of variation of dosage schedule,sex and age differences on immunogenicity in health care workers

Summary Of the medical staff of our hospital 217 members at high risk for hepatitis B were immunized with an experimental hepatitis B vaccine and anti-HBs titers used to study the influence of two dosage schedules, age, and sex on immunogenicity. Participants were 34 years of age (mean; range, 20–61); they were divided into two groups and vaccinated three times. Group A received 42 µg HBsAg for each vaccination. Group B received 84 µg for the first and 21 µg for the second and third vaccinations. The seroconversion rate was 32.7% after the first, 78.8% after the second, and 95.7% after the third vaccination. The participants who failed to produce anti-HBs titer (3 IU/l;n=9) or whose anti-HBs titers were below 50 IU/l (n=31) were vaccinated a fourth time. Only mild side effects of injections were observed in a third of all participants, usually in the form of a sore arm.Between groups A and B there were no significant differences as far as the seroconversion rate and anti-HBs titer were concerned. Nonresponders plus low-responders accounted for 19%. Female participants produced a markedly higher anti-HBs titer than males, and the female/male ratio among non- and low-responders was 1:2; among nonresponders, 1:2.5. There was a negative correlation of the anti-HBs titer with the age of the participants. These results not only have practical consequences for revaccination policy, but also offer the opportunity to further study the genetic regulation of the immune response to a complex peptide antigen in man.Abbreviations anti-HBc antibody to hepatitis B core antigen - anti-HBe antibody to hepatitis B e antigen - anti-HBs antibody to hepatitis B surface antigen - HBsAg hepatitis B surface antigen - IU/l international units per liter - MSD Merck, Sharp, and Dohme     

不同免疫方案制备抗HAb18G/CD147胞外区多克隆抗血清的比较

目的: 制备针对肝癌相关抗原HAb18G/CD147胞外区不同表位的抗血清, 比较不同免疫方案的免疫效果。方法: 以原核表达的GST -HAb18GEF融合蛋白、重组真核表达质粒pcDNA3 /HAb18G及HCC细胞为免疫原, 分别采用蛋白常规免疫、DNA肌肉免疫及pcDNA3 /HAb18G -HCCbooster(DNA -cellbooster)免疫接种BALB/c小鼠。采用间接ELISA和细胞ELISA, 同时测定免疫血清中抗变性和天然HAb18GEFIgG抗体的滴度和Ig亚类。用Westernblot检测各免疫方案制备的抗血清, 与变性HAb18GEF抗原结合的特异性。用免疫荧光法验证DNA- cellbooster免疫接种法制备的抗血清, 与细胞膜上天然HAb18G抗原的结合特异性。结果:以GST- HAb18GEF常规免疫后, 可诱导高滴度的IgG1抗体产生, 但针对的多为HAb18GEF的变性或线性表位; 以pcD -NA3 /HAb18G肌肉免疫后, 可诱导针对其天然表位的IgG2a抗体产生, 但滴度较低; 以DNA -cellbooster免疫后, 可诱导中等滴度、针对其天然表位的IgG2a和IgG1抗体产生。结论: 不同免疫方案可诱导针对HAb18GEF不同表位、不同滴度的多克隆抗血清, 为淘筛针对其不同表位的多样性抗体奠定了基础。     

Generation of high titer antisera in rabbits by DNA immunization

Mesothelin is a GPI-linked, membrane-associated differentiation antigen that is over-expressed in several forms of human cancers. Intradermal injection into rabbits of plasmid DNA encoding full length mesothelin resulted in antisera with titers as high as 1:100,000. Each immunization consisted of 320 microg of DNA delivered into 4 sites. After the initial three injections antisera titers were moderate (between 10 to 30,000) and fell over the course of about 7 weeks. When the titers had fallen, an injection of a booster dose of DNA resulted in very high titers of antisera. These antisera contained IgGs that could bind to both recombinant mesothelin made in Eschericha coli and to mesothelin present on human cells in Western blots and in immunofluorescence assays. These observations indicate that simple intradermal DNA immunization of rabbits can result in high titers of antibodies that can be used for a variety of purposes.     

Comparison of Four Different Carboxylterminal Tracers in a Radioimmunoassay Specific to the 68–84 Region of Human Parathyroid Hormone

Two synthetic carboxylterminal fragments, {tyr⁵²}hPTH(52–84) and {tyr⁶³}hPTH(63–84), and purified bPTH(1–84) were iodinated with ¹²⁵Iodine to be compared as tracers in a late carboxylterminal radioimmunoassay. Tracer ¹²⁵I-bPTH(41–84) was generated in vitro by incubating ¹²⁵I-bPTH(1–84) with plasma membranes of rat kidney cortex. Region specificity was achieved by saturating the unwanted middle component of our multivalent antiserum with a molar excess of hPTH(44–68). A charcoal-dextran separation was worked out for each tracer. The titer of the antiserum giving ?30% specific binding of each tracer was used in all experiments. Displacement of each tracer with increasing molar concentration of hPTH(1–84), hPTH(53–841, hPTH(41–84) and of hPTH (64–84) was studied, hPTH(41–84) was also generated by incubating hPTH(1–84) with rat cortex kidney membranes and was calibrated against a commercial preparation of bPTH(37–84). A progressive increase in the titer of the antiserum was seen as the molecular weight of the tracers decreased from a titer of 1/20,000 with ¹²⁵I-bPTH(1–84) to a titer of 1/50,000 with the two synthetic tracers. Similarly the so-called damage seen during the charcoal-dextran separation in absence of antibody was reduced from 16.0±6.2% (mean ±SD) with ¹²⁵I-bPTH(1–84) to 1.3±.2 with the two synthetic tracers. 50% displacement of the ¹²⁵I-bPTH(1–84) tracer was achieved at 13.2±.8 fmol/tube for hPTH(1–84) and at 6.3±1.0 fmol/tube for hPTH(41–84), reflecting the greater reactivity of fragments in that system. With the two synthetic tracers, a concentration of 5.0±.4 fmol/tube of hPTH(1–84) or of 3.5±1.2 fmol/tube of hPTH(41–84) was necessary to achieve the same goal. With ¹²⁵I-bPTH(41–84) results were between the two extremes. These results indicated that an increase in antiserum titer, a decrease in assay damage, an improvement in assay sensitivity and in comparative molar reactivity of the various circulating forms of hPTH can be achieved by using synthetic carboxylterminal fragments as tracers in region specific radioimmunoassays of hPTH.     

Antigenic relationship between the common antigen (OEP) of Pseudomonas aeruginosa and Vibrio cholerae.

Antibodies were found by the OEP-passive hemagglutination test to cross-react with the common antigen (OEP) of Pseudomonas aeruginosa in sera of rabbits immunized with two serotype (Inaba and Ogawa) strains of Vibrio cholerae. The titer in the OEP-passive hemagglutination reaction rose later than did the agglutinin titer and reached a peak of 640 to 1,280. The titers of OEP antibody formation in rabbits immunized with V. cholerae were almost the same as that of P. aeruginosa. The common antigen of P. aeruginosa was confirmed to exist serologically in both strains of V. cholerae as determined by the indirect fluorescent antibody test and the agar gel precipitin test. Passive immunization with the V. cholerae immune rabbit serum significantly protected mice against P. aeruginosa infection. Purified antibodies cross-reacting with the OEP of P. aeruginosa derived from the V. cholerae immune rabbit sera by OEP-coupled affinity chromatography protected mice against P. aeruginosa infection as compared with the control group, which was injected with 100 microgram of immunoglobin G not containing OEP antibody. The purified antibodies (2.5 microgram per mouse) protected animals challenged with approximately 10,000 50% lethal doses in the control group. Consequently, the common antigen (OEP) of P. aeruginosa proved to be a common antigen of V. cholerae both serologically and in possessing infection protective properties.     

Quantitation of secretory protein levels by radioimmunoassay

A radioimmunoassay was designed for the detection of secretory protein, a component of secretory immunoglobulin A, in human serum. The assay uses free secretory protein isolated from human colostrum, and antisera raised in rabbits to the purified antigen. The mean level of secretory protein in the control group was 2.34 +/- 0.41 microgram/ml (mean +/- S.E.M.). The level in cord blood was slightly lower (0.74 +/- 0.26 microgram/ml), while the level in patients with ovarian carcinoma was significantly increased (12.67 +/- 1.43 microgram/ml). Pregnant women have increasing secretory protein levels with increasing length of gestation (5.86 +/- 2.02, 11.55 +/- 1.30 and 17.00 +/- 1.16 microgram/ml for the first, second and third trimesters, respectively.     

Immunological nonidentity of Pseudomonas paucimobilis with Pseudomonas aeruginosa and Pseudomonas cepacia.

This investigation determined the serum agglutination activity and serum bactericidal response after rabbit immunization with Pseudomonas paucimobilis. Agglutination activity of antisera showed a twofold increase in titer from before immunization to 4 weeks post-immunization and peaked at 8 weeks post-immunization with a titer of 1:512. 2-Mercaptoethanol reduction of immunoglobulin M decreased agglutination titers. No major antigens were found to be common from crude antigen preparations of P. paucimobilis, Pseudomonas aeruginosa and Pseudomonas cepacia when tested with antisera to P. paucimobilis. Serum bactericidal activity was found in post-immunization antisera at 8 and 12 weeks against P. paucimobilis, with no activity present before immunization or at 4 weeks post-immunization. Antisera against P. paucimobilis showed no bactericidal activity against P. aeruginosa or P. cepacia.     

Estradiol induced alterations of the immune system--I. Enhancement of IgM production

Estrogens have been postulated as natural modulators of the immune system. In this study we have evaluated the effect of estradiol on in vivo immunoglobulin production in male rats. Administration of either a 75 microgram/kg or 750 microgram/kg dose of estradiol resulted in a dose-related increase of anti-sheep red blood cell antibody titers during a primary antibody response. These same animals when dosed with estradiol during a secondary antibody response showed an earlier appearance of the peak antibody titer in estradiol-treated rats as compared to controls. Rats dosed with estradiol only during the secondary antibody response period also showed a dose-related increase in Ab titer over control values but no shift in the time of appearance of the peak titer. Treatment of sera with 2-mercaptoethanol to evaluate IgG titers showed that 2-mercaptoethanol treatment both reduced the titer to control values and eliminated the estradiol-induced shift in the appearance of the peak antibody titer in rats given estradiol during the primary and secondary antibody response periods. Sera from animals dosed with estradiol during the secondary antibody response period only also showed titers reduced to control levels after 2-mercaptoethanol treatment of the sera. Estradiol-treated rats also had an increase in antibody titers to polysaccharide from Type III pneumococci, a T-cell independent antigen. While total antibody responses were increased following estradiol, there were no differences in the number of antibody-producing cells between control and estradiol-treated animals. The results of these studies suggest that estradiol exerts a direct effect on B cells resulting in increased synthesis of IgM antibodies. We cannot rule out, however, some modulation through regulatory T-cells.     

Hepatitis B vaccine in infants from an endemic area: long-term anti-HBs persistence and revaccination

Persistence of anti-HBs in 156 Senegalese infants immunized with hepatitis B vaccine was studied for periods ranging from 2 to 6 years after booster dose administration. Six years after the booster dose, 90.4% of the infants had detectable anti-HBs antibodies, with 78.1% having titers higher than 10 mIU/ml. The geometric mean titer was 60 mIU/ml. Females showed higher anti-HBs values than males. In a group of 11 infants who received no booster dose, anti-HBs antibodies were detectable 7 years after the first dose. However, the geometric mean titer was lower (26 mIU/ml). Revaccination (56 infants) led to an increase of the geometric mean titer to 469 mIU/ml 2 months later. These results show that a booster injection every 5-6 years should provide adequate protective anti-HBs levels in infants.