Antibody-secreting Cells In Spleen Research Articles

Adjuvants Enhance the Induction of Germinal Center and Antibody Secreting Cells in Spleen and Their Persistence in Bone Marrow of Neonatal Mice.

Immaturity of the immune system contributes to poor vaccine responses in early life. Germinal center (GC) activation is limited due to poorly developed follicular dendritic cells (FDC), causing generation of few antibody-secreting cells (ASCs) with limited survival and transient antibody responses. Herein, we compared the potential of five adjuvants, namely LT-K63, mmCT, MF59, IC31, and alum to overcome limitations of the neonatal immune system and to enhance and prolong responses of neonatal mice to a pneumococcal conjugate vaccine Pnc1-TT. The adjuvants LT-K63, mmCT, MF59, and IC31 significantly enhanced GC formation and FDC maturation in neonatal mice when co-administered with Pnc1-TT. This enhanced GC induction correlated with significantly enhanced vaccine-specific ASCs by LT-K63, mmCT, and MF59 in spleen 14 days after immunization. Furthermore, mmCT, MF59, and IC31 prolonged the induction of vaccine-specific ASCs in spleen and increased their persistence in bone marrow up to 9 weeks after immunization, as previously shown for LT-K63. Accordingly, serum Abs persisted above protective levels against pneumococcal bacteremia and pneumonia. In contrast, alum only enhanced the primary induction of vaccine-specific IgG Abs, which was transient. Our comparative study demonstrated that, in contrast to alum, LT-K63, mmCT, MF59, and IC31 can overcome limitations of the neonatal immune system and enhance both induction and persistence of protective immune response when administered with Pnc1-TT. These adjuvants are promising candidates for early life vaccination.

Transcriptomics of the Vaccine Immune Response: Priming With Adjuvant Modulates Recall Innate Responses After Boosting.

Transcriptomic profiling of the immune response induced by vaccine adjuvants is of critical importance for the rational design of vaccination strategies. In this study, transcriptomics was employed to profile the effect of the vaccine adjuvant used for priming on the immune response following re-exposure to the vaccine antigen alone. Mice were primed with the chimeric vaccine antigen H56 of Mycobacterium tuberculosis administered alone or with the CAF01 adjuvant and boosted with the antigen alone. mRNA sequencing was performed on blood samples collected 1, 2, and 7 days after priming and after boosting. Gene expression analysis at day 2 after priming showed that the CAF01 adjuvanted vaccine induced a stronger upregulation of the innate immunity modules compared with the unadjuvanted formulation. The immunostimulant effect of the CAF01 adjuvant, used in the primary immunization, was clearly seen after a booster immunization with a low dose of antigen alone. One day after boost, we observed a strong upregulation of multiple genes in blood of mice primed with H56 + CAF01 compared with mice primed with the H56 alone. In particular, blood transcription modules related to innate immune response, such as monocyte and neutrophil recruitment, activation of antigen-presenting cells, and interferon response were activated. Seven days after boost, differential expression of innate response genes faded while a moderate differential expression of T cell activation modules was appreciable. Indeed, immunological analysis showed a higher frequency of H56-specific CD4+ T cells and germinal center B cells in draining lymph nodes, a strong H56-specific humoral response and a higher frequency of antibody-secreting cells in spleen of mice primed with H56 + CAF01. Taken together, these data indicate that the adjuvant used for priming strongly reprograms the immune response that, upon boosting, results in a stronger recall innate response essential for shaping the downstream adaptive response.

Recombinant hemagglutinin proteins formulated in a novel PELC/CpG adjuvant for H7N9 subunit vaccine development

Humans infected with H7N9 avian influenza viruses can result in severe pneumonia and acute respiratory syndrome with an approximately 40% mortality rate, and there is an urgent need to develop an effective vaccine to reduce its pandemic potential. In this study, we used a novel PELC/CpG adjuvant for recombinant H7HA (rH7HA) subunit vaccine development. After immunizing BALB/c mice intramuscularly, rH7HA proteins formulated in this adjuvant instead of an alum adjuvant elicited higher IgG, hemagglutination-inhibition, and virus neutralizing antibodies in sera; induced higher numbers of H7HA-specific IFN-γ-secreting T cells and antibody secreting cells in spleen; and provided improved protection against live virus challenges. Our results indicate that rH7HA proteins formulated in PELC/CpG adjuvant can induce potent anti-H7N9 immunity that may provide useful information for H7N9 subunit vaccine development.

Deletion or inhibition of Fc gamma receptor 2B (CD32) prevents FVIII-specific activation of memory B cells in vitro.

Development of inhibitory antibodies against factor VIII (FVIII) is a severe complication of replacement therapy in haemophilia A. Patients with inhibitors are treated with high FVIII doses in the context of immune tolerance therapy (ITT). Data from haemophilia A mouse model suggest that high FVIII concentrations prevent the formation of antibody secreting cells (ASCs) from memory B cells (MBCs) by inducing apoptosis. Fc gamma receptor 2B (CD32) is an important regulator of B cell function, mediating inhibitory signals after cross-linking with the B cell receptor. Here, the role of CD32 in the regulation of FVIII-specific MBCs was investigated using F8-/- and F8-/-CD32-/- knockout mice and monoclonal antibodies (mAbs). The initial immune response was similar between F8-/- and F8-/-CD32-/- mice, including concentration of anti-FVIII antibodies and number of FVIII-specific ASCs in spleen and bone marrow. In contrast, formation of ASCs from MBCs upon rhFVIII re-stimulation in vitro was abolished in F8-/-CD32-/- mice, whereas FVIII/anti-FVIII immune complexes significantly enhanced ASC formation in F8-/- mice. Inhibition of CD32 by mAbs or F(ab)2 fragments prevented ASC formation in a dose-dependent manner. Transfer of B cell-depleted splenocytes using CD45R (B220) depletion from CD32-competent mice did not restore ASC formation in F8-/-CD32-/- cells confirming that CD32 is required on B cells. We conclude that CD32 is a crucial regulator of FVIII-specific B cells and is required for the differentiation of MBCs into ASCs. Inhibition of CD32 could potentially improve the efficacy of FVIII in the context of ITT.

Pneumococcal Polysaccharide Abrogates Conjugate-Induced Germinal Center Reaction and Depletes Antibody Secreting Cell Pool, Causing Hyporesponsiveness

BackgroundPlain pneumococcal polysaccharide (PPS) booster administered during second year of life has been shown to cause hyporesponsiveness. We assessed the effects of PPS booster on splenic memory B cell responses and persistence of PPS-specific long-lived plasma cells in the bone marrow (BM).MethodsNeonatal mice were primed subcutanously (s.c.) or intranasally (i.n.) with pneumococcal conjugate (Pnc1-TT) and the adjuvant LT-K63, and boosted with PPS+LT-K63 or saline 1, 2 or 3 times with 16 day intervals. Seven days after each booster, spleens were removed, germinal centers (GC), IgM+, IgG+ follicles and PPS-specific antibody secreting cells (AbSC) in spleen and BM enumerated.ResultsPPS booster s.c., but not i.n., compromised the Pnc1-TT-induced PPS-specific Abs by abrogating the Pnc1-TT-induced GC reaction and depleting PPS-specific AbSCs in spleen and limiting their homing to the BM. There was no difference in the frequency of PPS-specific AbSCs in spleen and BM between mice that received 1, 2 or 3 PPS boosters s.c.. Repeated PPS+LT-K63 booster i.n. reduced the frequency of PPS-specific IgG+ AbSCs in BM.ConclusionsPPS booster-induced hyporesponsiveness is caused by abrogation of conjugate-induced GC reaction and depletion of PPS-specific IgG+ AbSCs resulting in no homing of new PPS-specific long-lived plasma cells to the BM or survival. These results should be taken into account in design of vaccination schedules where polysaccharides are being considered.

Long-term Persistence of Anti-factor VIII Antibody-secreting Cells in Hemophilic Mice after Treatment with Human Factor VIII

The analysis of anti-factor VIII (FVIII) antibody-secreting cells (ASC) at different anatomic sites provides valuable information about the nature of the anti-FVIII immune response in hemophilic mice after treatment with human FVIII. An Elispot system is described that is suitable for analyzing frequencies and IgG subclasses of anti-FVIII ASC at the single-cell level. Hemophilic mice were treated with four doses of FVIII. Anti-FVIII antibodies in blood as well as anti-FVIII ASC in spleen and bone marrow were analyzed after each dose of FVIII and subsequently up to 22 weeks after termination of the FVIII treatment. Anti-FVIII ASC first appeared in the spleen where they were detectable after two intravenous doses of FVIII. Their appearance correlated with that of anti-FVIII antibodies in blood plasma. Anti-FVIII ASC in bone marrow were detectable after three doses of FVIII and were probably cells that initially formed in the spleen and subsequently migrated to the bone marrow. Whereas the frequency of anti-FVIII ASC in the spleen increased up to the fourth dose of FVIII and declined thereafter, in the bone marrow it remained constant for up to at least 22 weeks after the termination of the FVIII treatment. Titers of anti-FVIII antibodies in blood plasma increased up to the fourth dose of FVIII, then remained high constantly for 14 weeks and decreased but the antibodies were still detectable for up to at least 22 weeks after the fourth dose of FVIII. The IgG-subclass distribution of anti-FVIII ASC was similar in spleen and bone marrow and matched the subclasses of anti-FVIII antibodies in blood plasma indicating that both organs contribute to circulating antibodies in the blood.

Effect of ascorbic acid supplementation on the immune response of chickens vaccinated and challenged with infectious bursal disease virus

One-day-old chickens were divided into two groups and reared under similar conditions. One group was fed a diet supplemented with 1000 ppm ascorbic acid and the other group was fed an identical diet, but not supplemented with ascorbic acid. Both groups were vaccinated against infectious bursal disease (IBD) at 7 days of age and challenged orally with 4×10 5 of 50% embryo-lethal-dose IBDV 14 days later. The number of anti-IBDV antibody secreting cells, production of interleukin-2 (IL-2) by splenocytes, number of CD4 +, CD8 + and IgM + cells in spleen and IgM + cells in bursa of Fabricius were compared between the two groups at 7 days (prior to vaccination), 21 days (14 days post-vaccination and prior to challenge) and 31 days (10 days post-challenge) of age. The number of CD8 + in spleen at 7 days of age and IgM + cells in bursa at 7, 21 and 31 days of age were significantly higher in ascorbic acid supplemented group ( P<0.05). Production of IL-2 by splenocytes was higher as indicated by higher stimulation indices in ascorbic acid supplemented group. The number of anti-IBDV IgG antibody secreting cells in spleen at 21 and 31 days of age were significantly higher in ascorbic acid supplemented group ( P<0.05). Dietary supplementation of ascorbic acid may ameliorate the immunosuppression caused by IBDV vaccination and improve humoral and cellular immune responses.

ラット歯肉への抗原接種による免疫応答に関する研究

It was expected that the bacterial plaque in the gingival crevice elicited immune response in periodontal diseases. The purpose of this paper is to clarify the immune response which is elicited by the antigens injected from periodontium in rats. Rats were immunized by the gingival injection of proteins, lipopolysaccharide (LPS) and ultrasonicated extracts of Escherichia coli, Actinomyces naeslundii, Porphyromonas gingivalis for three times a month. The number of the antibody-secreting cells in spleen and submandibullar lymph nodes were counted. The IgG subclasses of antigen specific antibodies were determined. The concentrations of cytokines which may affect the antibody secretion were also measured. In the results of antibody-secreting cells, all of antigens induced antibody secretion in submandibullar lymph nodes, LPS greatly induced that in spleen as well. The predominant antibody in response to protein antigens was IgG1 subclass, that to LPS was IgG2a subclass, and that to three bacterial extracts was IgG2a subclass. The results showed that the subclass of antibody secretion in response to the immunization depended on the chemical composition of antigen. The concentration of interleukin (IL)-1 decreased and that of IL-6 increased in the serum after three times gingival injections of all kinds of antigens. The result showed that LPS greatly induced the response both in lymph nodes and in spleen. It was well-known that the concentration of LPS in periodontal tissue of the patients was higher than that of normal subjects. It was suggested that the immune response in periodontal disease occurred both in neighboring periodontal tissue and in central immune organ.

Immunostimulation by a partially modified retro-inverso-tuftsin analog containing Thr1.sum..psi.[NHCO](R,S)Lys2 modification

The tuftsin retro-inverso analogue H-Thr psi[NHCO](R,S)Lys-Pro-Arg-OH was synthesized through a novel procedure for the high-yield incorporation of isolated retro-inverso bonds into peptide chains and the use of the new Meldrum's acid derivative (CH3)2C(OCO)2CH(CH2)4NHCOCF3 followed by its efficient coupling in solution to trimethylsilylated H-D-Thr(t-Bu)NH2. Closely related peptide impurities were eliminated both from the crude final peptide and the fully protected tetrapeptide amide precursor via ion-exchange and reversed-phase displacement chromatography, respectively. The tuftsin retro-inverso analogue proved to be completely resistant to enzymatic degradation in vitro, either against isolated aminopeptidases or human plasma proteolytic enzymes. When administered either orally or intravenously, it was significantly more active than normal tuftsin in increasing the number of specific antibody secreting cells in spleen of mice immunized with sheep erythrocytes. Furthermore, the analogue exerted an enhanced stimulatory effect on the cytotoxic activity of splenocytes against YAC-1 tumor cells. Finally, retro-inverso-tuftsin was about 10-fold more potent than the native peptide in reducing rat adjuvant arthritis. The resistance of the retro-inverso analogue to peptidases might explain the increased in vivo activities and allows its further immunopharmacological characterization.