Lectin-induced modulation of the antibody response to type III pneumococcal polysaccharide

Several lectins were tested for their capacity to alter the antibody response to type III pneumococcal polysaccharide (SSS-III). The antibody response was enhanced by concanavalin A (Con A), phytohemagglutinin (PHA), as well as lectins from Phytolacca americana (Pa-2), Pisum sativum (PSA), and Lens culinaris (LCH), when these lectins were given 2 days after immunization with SSS-III; however, suppression was obtained when Con A and Pa-2 were given at the time of immunization. By contrast the lectins from Vicia villosa (VVL) and Bauhinia purpurea (BPA) did not alter the antibody response. Since the lectins PSA and LCH bind to the same monosaccharide as Con A, whereas the other lectins bind to different monosaccharides, these findings indicate that there is no relationship between nominal monosaccharide specificity and the capacity to modulate the antibody response. Substantial increases in the magnitude of the IgG₁ antibody response was noted after the administration of Con A whereas profound enhancement of IgG_2a antibody response was noted after PHA was given.     

Morphology of the antibody response to pneumococcal polysaccharide in mice.

In the course of an antibody immune response to pneumococcal polysaccharide - type III (S III) in mice a slight increase was observed in the proportion of plasma cells among the antibody-producing cells, reaching its peak at the time of decline of this reaction. On the basis of ultrastructural resemblance of these plasma cells to primitive reticular cells and in view of other specificities of the immunological response to S III antigen, the author presumes direct reticular origin of anti-S III antibody-producing plasma cells.     

Genetic control of the immune response of mice to type III pneumococcal polysaccharide

BALBc mice immunized with Type III pneumococcal polysaccharide (SIII) had higher numbers of IgM plaque-forming cells (PFC) in the spleen than similarly immunized C57BL/Ks mice. The F₁ hybrids of these two strains had intermediate numbers of SIII-specific PFC. Analysis of the responses of F₂ and backcross strains indicated that the observed responses were compatible with results expected for control of the immune response to SIII at a single autosomal locus.     

Sensitivity of amplifier T cells involved in the antibody response to type III pneumococcal polysaccharide to anti-lymphocyte serum.

Amplifier T cells responsible for enhancement of the antibody response to type III pneumococcal polysaccharide have been shown to be resistant to the effects of antilymphocyte serum (ALS) given at the time of immunization, a treatment that eliminates suppressor T cell activity. The resistance of amplifier T cells to ALS can be attributed to the fact that their activity develops after that of suppressor T cells. ALS given 1 or 2 days after immunization does abrogate amplifier T cell activity, independent of the mode by which that activity is elicited. The data emphasize the importance of kinetic considerations in understanding the effects produced by immunologically active agents such as ALS.     

Suppression of the antibody response to type III pneumococcal polysaccharide with antigen coupled to syngeneic lymphoid cells

Nine allophenic mice of the type C57BL/10Sn … A were analyzed quantitatively, at weekly intervals over a period of 6 weeks, for the relative parental contributions to their red blood cell and white blood cell populations. It was found that four of the mice showed a significant change (termed “chimeric drift”) in the parental composition of their peripheral white blood cells, as determined by cytotoxicity testing. Six of the mice analyzed showed chimeric drift in their red blood cell population, as determined by hemoglobin analysis on isoelectric focusing gels. The isoelectric points of the hemoglobins of six inbred strains of mice were determined as an outgrowth of this study. Chimeric drift was observed in the direction of either parental cell type, and was found to be independent of the coat color, age, or sex of the mice.     

Neonatal infection with mouse thymic virus: effects on cells regulating the antibody response to type III pneumococcal polysaccharide.

Mice infected neonatally with mouse thymic virus (TA) were evaluated at different ages with respect to their ability to give a plaque-forming cell (PFC) response to type III pneumococcal polysaccharide (SSS-III), as well as the degree of amplifier and suppressor thymus-derived (T) cell activity present. B cell activity matured rapidly from 2 to 4 weeks of age and was not affected by TA infection. Amplifier T cell activity matured progressively over the first 8 weeks of life and was transiently suppressed in TA-infected mice at 4 weeks of age. Suppressor T cell activity measured at 2,4, and 6 weeks of age was unaffected by TA. The findings suggest that TA is highly tropic for T cells and has selective effects on subpopulations of T cells.     

Selective sensitivity to hydrocortisone of regulatory functions that determine the magnitude of the antibody response to type III pneumococcal polysaccharide.

Previous studies on the basis for the immunosuppressive potential of adrenal corticosteroids have stressed that the effects of these agents on immune functions depend on the animal species being considered, as well as the subpopulations of lymphocytes involved in the expression of immune functions examined. In the present work, we have evaluated the effect of a single dose of hydrocortisone on three different immunoregulatory functions that can influence the magnitude of an antibody response to Type III pneumococcal polysaccharide (SSS-III) in mice; these functions include suppressor, amplifier, and helper activity that are dependent upon the presence of distinct subpopulations of thymus-derived (T) cells. The results obtained show that a single injection of a relatively large dose of hydrocortisone, when given at the time of priming with carrier, eliminated all evidence of carrier-specific helper T cell activity; hydrocortisone was also found to eliminate a significant amount of helper T cell activity when given after such activity had been generated. But, under the same experimental conditions, suppressor and amplifier T cell activities were unaffected, even in this steroid-sensitive species. Such selective sensitivity may account for some of the immunosuppressive potency of steroids.     

Regulation of the antibody response to type III pneumococcal polysaccharide. V. Ontogeny of factors influencing the magnitude of the plaque-forming cell response.

Mice of different ages were evaluated with respect to their ability to give a plaque-forming cell (PFC) response to Type III pneumococcal polysaccharide (SSSIII), as well as the degree of amplifier and suppressor thymus-derived(T) cell activity present. Although the magnitude of the PFC response to an optimally immunogenic dose of SSS-III for 2-and 3-week old mice was only 7% and 14%, respectively, of that produced by adult (8-week old) mice, values comparable to those of adult animals were attained by 4 weeks of age; no significant changes in the ability to respond to SSS-III occurred thereafter. Amplifier T cell activity, which was minimal at 2 to 4 weeks of age, matured slowly and did not reach a maximum until 8 to 10 weeks of age. By contrast, suppressor T cell activity appeared to be fully developed at least as early as 2 weeks of age; here, the inhibitory effects produced could by abrogated by depletion of T cells, indicating that the unresponsiveneness induced by such cells does not result in the depletion ot irreversible inactivation of B cells capable of responding to SSS-III. These findings suggest that the inhibitory effects of suppressor T cells are predominant in young mice and that such cells may play an important role in determining the ease with which unresponsiveness is induced in neonates, and in the prevention of autoimmune disease. Also, studies conducted with adult-thymectomized mice showed that both amplifier and suppressor T cells, once seeded to the periphery, are stable and do not depend upon the presence of intact thymus for the expression or renewal of their activity.     

Cell surface antigens and other characteristics of T cells regulating the antibody response to type III pneumococcal polysaccharide

The administration of a subimmunogenic dose of type III pneumococcal polysaccharide (SSS-III) produces an antigen-specific T cell-dependent phenomenon termed low-dose paralysis (immunologic unresponsiveness). This form of unresponsiveness can be transferred by spleen cells obtained 5 to 24 hr after priming, and the suppressive activity of the transferred cells is abolished by prior treatment with monoclonal anti-Lyt-2 and anti-I-J antibody in the presence of complement, indicating that suppression is mediated by a distinct subset of T cells (suppressor T cells). If primed spleen cells are transferred 24 to 72 hr after immunization with SSS-III, however, the resulting antibody response of immunized recipients is enhanced. Greater enhancement is noted when transferred cells, pretreated with monoclonal anti-Lyt-2 antibody plus complement to remove suppressor T cells, are used; such enhancement is attributed to amplifier T cells. These findings indicate suppressor T cells regulate the antibody response to SSS-III by influencing the expansion of SSS-III-specific clones of B cells as well as the expression of amplifier T cell activity; the latter causes B cells to proliferate further in response to SSS-III.     

Induction of primary and inhibition of secondary antibody response to hapten by hapten conjugates of type III pneumococcal polysaccharide.

Tri- or dinitrophenylated pneumococcal polysaccharide type III (TNP- or DNP SIII)) induced a primary 19S anti-TNP response without generating immunological memory to the hapten in LAF₁ mice. Hapten-hemocyanin (TNP-KLH) or hapten conjugates of B. abortus organisms (DNP-BA) induced both 19S and 7S primary responses and memory to the hapten. Spleen cells from mice immunized with TNP-KLH or DNP-BA did not give adoptive memory responses upon challenge with hapten-SIII and, in fact, were inhibited from responding to their homologous hapten conjugates by simultaneous injection of hapten-SIII. Incubation of TNP-KLH-primed spleen cells for as short as 5 min at 0 °C with 10 μg of TNP-SIII per milliliter virtually abolished their ability to give 19S and 7S memory responses to TNP-KLH upon transfer into irradiated recipients. It is suggested that a difference in avidity and/or number of anti-TNP receptors per cell between virgin and primed B cells may be an important factor in determining whether the cells will be stimulated or inhibited by exposure to hapten-SIII. Another factor may be a difference between virgin and memory cells in their requirement for T-cell help.     

The effect of Bordetella pertussis lymphocytosis-promoting factor (LPF) on antibody response in mice: its enhancing and suppressive effects

The effect of lymphocytosis-promoting factor (LPF) on antibody response in mice was estimated under different sets of experimental conditions. Four- and 6-week-old mice were intravenously inoculated with LPF. Three days later these mice were inoculated either intraperitoneally or intravenously with sheep red blood cell (SRBC) or human serum albumin (HSA) as an antigen. The adjuvant effect of LPF was demonstrated on antibody response in 6-week old mice to intraperitoneally inoculated SRBC but not to intravenously-inoculated one. When 4-week-old mice were immunized, hemagglutinin production in response to intraperitoneally inoculated SRBC was not enhanced by LPF. In addition, a rather suppressive effect of LPF at a comparatively high dose was demonstrated on hemagglutinin production in response to intravenously inoculated SRBC. Anti-HSA production was enhanced by inoculation of LPF in any combination of the mouse age and the route of antigen administration. These findings indicate that the adjuvant effect of LPF on antibody response in mice depends upon experimental conditions: the age of mice, the quality of antigen and the route of antigen administration used for immunization.     

Kinetics of the antibody response to type III pneumococcal polysaccharide. II. Factors influencing the serum antibody levels after immunization with an optimally immunogenic dose of antigen.

When the number of PFC present in the spleen was measured at 24-hr intervals after immunizing with an optimally immunogenic dose of type III pneumococcal polysaccharide (SSS-III), maximal numbers of PFC were attained 4 days after immunization; thereafter, the number of PFC decreased rapidly. By contrast, serum antibody levels, which were measured in the same mice using a Farr test, reached peak values 5 days after immunization and then declined much more slowly than did the number of PFC. Two factors were found to contribute to this disparity. First, experiments conducted with splenectomized mice showed that extrasplenic antibody synthesis, which began between days 3 and 4 after immunization and peaked on days 6 to 7, accounted for nearly one-third of the total amount of serum antibody produced. Second, the average rate of antibody synthesis by PFC increased through day 6 after immunization and then declined. Antigen-antibody dissociation tests showed that the avidity of the serum antibody obtained 4 to 7 days after immunization was the same. Moreover, during the same interval, all the antibody detected by the Farr test was of the IgM class. Thus, a change in avidity or class of immunoglobulin after day 5 did not account for the disparity observed. The clearance rate of antibody injected i.v. into nonimmune and immunized mice was studied. The data obtained indicated that accelerated clearance of antibody was occurring prior to day 3 after immunization; however, after day 3 the antibody clearance rate was constant and was the same as that found when antibody was injected into nonimmune mice. These findings affirmed the results of previous studies showing that treadmill neutralization was not important in determining the serum antibody levels present after immunization with an optimally immunogenic dose of SSS-III.     

Role of CR2 in the human adult and neonatal in vitro antibody response to type 4 pneumococcal polysaccharide.

A number of studies have indicated that the complement receptor type 2 (CR2), which is the receptor for C3d, a degradation fragment of the complement component C3, regulates B lymphocyte activation and growth. Early reports have described that C3 regulates T cell-dependent (TD) antibody responses. The involvement of CR2 in the antibody response to T cell-independent type 2(TI-2) antigens was investigated because neonatal B cells, which are unresponsive to TI-2 antigens both in vivo and in vitro, express a significantly decreased level of CR2 as compared to B cells of adult donors. We utilized type 4 pneumococcal polysaccharide (PS4) as a model TI-2 antigen. In order to study the relationship between CR2 and the response to PS4, B cells were costimulated with PS4 and monoclonal antibodies (MAb) to CR2. HB5 and OKB7 anti-CR2 monoclonal antibodies enhanced the in vitro response of adult B cells to PS4, as measured in a PS4-specific spot-forming cell assay. Neonatal B cells could only be induced to respond to PS4 using high concentrations of OKB7 anti-CR2 MAb. The 8-mercaptoguanosine (8MGuo), an agent that can overcome the in vitro unresponsiveness to PS4 of neonatal B cells, increased CR2 expression on adult and neonatal B cells. Furthermore, 8MGuo synergizes strongly with anti-CR2 antibodies in augmenting the anti-PS4 antibody response. Data presented in this report provide evidence of CR2 involvement in the antibody response to PS4 and that the neonatal B cell unresponsiveness to TI-2 antigens may be due to the decreased expression of CR2.