Antibody response of immunodeficient (xid) CBA/N mice to Escherichia coli 0113 lipopolysaccharide, a thymus-independent antigen.

CBA/N mice, which possess an X-linked immunodeficiency (xid), produce a convincing antibody response to lipopolysaccharide derived from Escherichia coli 0113 (LPS 0113), a thymus-independent antigen. The antibody response produced was shown to be specific for the O-polysaccharide moiety of LPS 0113, rather than lipid A or lipid-A-associated protein. The relevance of this finding to the nature of the genetic defect of xid-mice is discussed.

Cyclic development of immunological memory to bacterial lipopolysaccharide.

Immunological memory to the lipopolysaccharide of Escherichia coli O113 was generated in strains of inbred mice given a single subimmunogenic dose of either E. coli O113 lipopolysaccharide or the native protoplasmic polysaccharide of E. coli O113. Such memory, which only involved antibody of the immunoglobulin M class, developed in a cyclic manner that was characteristic for the strain of mice used. It involved cell proliferation as well as differentiation and persisted for at least 25 days after priming with a single injection of a subimmunogenic dose of E. coli O113 lipopolysaccharide.

Modulation of the immune response to lipopolysaccharide.

Mice given a single optimally immunogenic dose (20 micrograms) of bacterial LPS make an antibody response that is characterized by cyclic (oscillatory) patterns. This kinetic pattern is dose as well as mouse strain dependent. LPS can induce a secondary response in BALB/c mice that is also cyclic, although it differs in amplitude as well as periodicity from a primary response. To rule out the involvement of B cell mitogenic activity of LPS in the expression of such cyclic patterns, the responses produced by both C3H/HeN and C3H/HeJ mice to a single injection of LPS were compared; the latter do not give B cell proliferative responses to LPS and also have been reported to give low LPS-specific responses in vivo. Both strains gave an oscillatory kinetic pattern. By contrast, BALB/c nu/nu mice given an optimal immunogenic dose of LPS (2 micrograms) do not present a cyclic immune response. This indicates that mature T cells are required for the generation of an oscillatory anti-LPS response.

Study of the idiotypy of lipopolysaccharide-specific polyclonal and monoclonal antibodies.

The monoclonal antibodies produced by a variety of hybridomas making antibody specific for E. coli 0113 lipopolysaccharide (LPS) were purified by affinity chromatography and their fine specificity studied. All reacted specifically with the polysaccharide moiety of LPS from E. coli 0113 and from Neisseria lactamica; two reacted with LPS from Pseudomonas aeruginosa and one reacted with LPS from Klebsiella pneumoniae. Polyclonal and monoclonal syngeneic and semi-syngeneic anti-idiotypic antisera were produced to study the idiotypy of LPS-specific monoclonal antibodies which express a complex cross-reactive idiotype (IdX) as well as individual idiotypes. E. coli 0113 LPS-specific antibodies produced by BALB/c mice express this IdX and the kinetics for its expression was examined using mice either primed or hyperimmunized with LPS; idiotypic maturation was observed, but we were unable to detect an auto-anti-idiotypic antibody response. This IdX was expressed on E. coli 0113 LPS-specific antibodies from all strains of mice examined, indicating that its expression is not restricted by genes linked to the IgCH locus.

Adjuvant effects of trehalose dimycolate on the antibody response to type III pneumococcal polysaccharide.

Treatment with trehalose dimycolate (TDM) increases the magnitude of the immunoglobulin M (IgM) antibody response of mice to type III pneumococcal polysaccharide (SSS-III). Such enhancement is demonstrable over a wide range of immunizing doses and does not require thymus-derived (T) cells to be elicited. Although young adult mice immunized with SSS-III do not usually make anti-SSS-III antibodies of the IgG1 and IgG3 classes, antibodies of one or both isotypes were produced after immunization and treatment with TDM and/or monophosphoryl lipid A (MPL); the additive nature of the effect produced by both TDM and MPL suggests that the two immunomodulators act by different mechanisms. TDM and MPL have different effects on the induction and expression of low-dose immunological paralysis, a form of unresponsiveness known to be mediated by suppressor T cells. The relevance of these findings to the modes of action of TDM and MPL is discussed.

Characterization of the immunodeficiency of RIIIS/J mice: immune response to polysaccharide antigens.

RIIIS/J mice lack an autosomal dominant gene(s) that influences the magnitude of the antibody response to several polysaccharide antigens of bacterial origin. Low responsiveness is demonstrable whether polysaccharide is administered as a T-helper-cell-independent or -dependent antigen conjugated to an immunogenic carrier; however, RIIIS/J mice make good anti-hapten antibody responses to haptenated polysaccharides. The low antibody responses of RIIIS/J mice to type III pneumococcal polysaccharide do not appear to be the results of an imbalance in the activity of regulatory T lymphocytes. Compared with other strains of mice, RIIIS/J mice elicit low antibody responses to lipopolysaccharide (LPS). They do not develop a cyclic primary or secondary antibody response to Escherichia coli O113 LPS; the latter is not due to a lack of mitogenic response to E. coli O113 LPS. They also produce auto-anti-idiotypic antibody after being immunized with trinitrophenyl-Ficoll.

Immunomodulatory activity of monophosphoryl lipid A in C3H/HeJ and C3H/HeSnJ mice.

Treatment with nontoxic monophosphoryl lipid A (MPL) derived from a polysaccharide-deficient, heptoseless Re mutant of either Salmonella typhimurium or Salmonella minnesota R595 enhanced the immunoglobulin M (IgM) anti-type III pneumococcal polysaccharide (SSS-III) antibody response of C3H/HeSnJ mice. Such an adjuvant effect was not observed in lipopolysaccharide-nonresponder C3H/HeJ mice. Nevertheless, C3H/HeJ spleen cells produced a weak mitogenic response to both preparations of MPL in vitro, and C3H/HeJ mice showed a significant increase in serum IgM levels without an increase in numbers of splenic IgM-secreting plaque-forming cells after in vivo treatment with MPL. A significant increase in serum IgG3 levels was accompanied by a transient decrease in serum IgG1 levels in C3H/HeSnJ mice given MPL; such non-antigen-specific polyclonal effects were not observed in C3H/HeJ or in athymic nu/nu mice. Since the enhanced antibody response to SSS-III has been attributed to the inactivation of suppressor T cells by MPL and since suppressor-T-cell activity is demonstrable in both C3H/HeSnJ and C3H/HeJ mice, these findings imply that (i) the suppressor T cells of C3H/HeJ mice are refractory to inactivation by MPL and (ii) some of the polyclonal and mitogenic effects produced in C3H/HeJ mice are due to the direct action of MPL on B lymphocytes.

Characterization of the immunodeficiency of RIIS/J [corrected] mice. I. Association with the CD5 (LY-1) [corrected] B cell lineage.

RIIIS/J mice produce low antibody responses to several polysaccharide Ag of bacterial origin. They have low levels of serum IgM and IgG3 and high levels of serum IgG2a and IgG2b. Low serum IgM and IgG3 have been attributed to a low frequency of CD5 (Ly-1) B cells, which play an important role in the production of natural antibodies. Indeed, RIIIS/J mice have a low frequency of CD5 (Ly-1)+, IgM bright+, Ly-5 (B220)dull+ (i.e., CD5 (Ly-1) B) cells in their peritoneum. RIIIS/J mice treated with LPS produce a low anti-bromelain-treated mouse RBC splenic plaque-forming cell response and a normal anti-mouse transferrin splenic PFC response. Those data are compatible with the fact that CD5 (Ly-1) B cells contain the precursors of B lymphocytes secreting anti-bromelain-treated mouse RBC antibody. However, they have a higher frequency of IgM bright+, Mac-1+ cells in their peritoneum. These cells represent the CD5 (Ly-1) "sister population" of CD5 (Ly-1) B cells described by others. This suggests that characteristics usually associated with the CD5 (Ly-1) lineage are applicable only to the CD5 (Ly-1)+ Mac-1+ IgM+ population, but not the related CD5 (Ly-1)- Mac-1+ IgM+ population. RIIIS/J mice should thus prove a valuable model to study the CD5 (Ly-1) B cell lineage.

Inactivation of suppressor T-cell activity by nontoxic monophosphoryl lipid A.

Treatment with nontoxic monophosphoryl lipid A (MPL), which was derived from a polysaccharide-deficient, heptoseless Re mutant of Salmonella typhimurium, was found to inactivate suppressor T-cell activity, as evidenced by a decrease in the degree of low-dose immunological paralysis expressed and an increase in the magnitude of the antibody response to type III pneumococcal polysaccharide. The effects produced, which could not be attributed to the polyclonal activation of immune B cells by MPL, were dependent upon the dose of MPL used, as well as the time when MPL was given relative to low-dose priming or immunization with type III pneumococcal polysaccharide. Neither amplifier nor helper T-cell activity was decreased by treatment with the same, or larger, doses of MPL. The significance of these findings to the use of MPL as an immunological adjuvant or an immunomodulating agent is discussed.

Study of idiotopic suppression induced by anti-cross-reactive idiotype monoclonal antibody in the anti-p-azophenylarsonate antibody response.

A/J mice immunized with p-azophenylarsonate coupled to keyhole limpet hemocyanin produce antibodies expressing a cross-reactive idiotype (CRIA). The pretreatment of A/J mice with anti-idiotypic polyclonal or monoclonal antibody directed against the major cross-reactive idiotype (CRIA) borne by p-azophenylarsonate-specific antibody can lead to idiotypic suppression. In this study, we investigate this idiotypic suppression by using four mAb2 (E4, H8, E3, 2D3) recognizing distinct idiotopes whose expression is related to the presence of particular gene segments of the heavy chain V region. 2D3 expression has been related to the presence of some amino acid in the CDR2 region of the VH gene segment derived from the germ line VH IdCR11. So far, the latter is the only germ-line gene coding for CRIA+ antibody that has been identified in the A/J genome. E4 and H8 expression has been related to the use of a particular D segment, whereas E3 expression has been attributed to certain combinations of D and JH segments. Therefore, we might expect independent regulation of the expression of those various idiotopes in relation to the mechanism of gene recombination. Indeed, we observed that 2D3-suppressed A/J mice still produce the three other idiotopes, suggesting the recombination of those particular D and J segments with a different VH gene. Such a gene has been identified in the genome of BALB/c mice. A/J mice pretreated with one of the other three mAb2 are generally cosuppressed for the expression of E4, H8, and E3, but they still produce 2D3+ antibody. In this case, the IdCR11 VH germ-line gene is most probably recombined with different D and J segments. Molecular evidence for the existence of such molecules has also been presented in the literature. So our serologic data on idiotopic suppression in the arsonate system can be compared with recent data provided by molecular genetics.

Ability of monophosphoryl lipid A to augment the antibody response of young mice.

Treatment with nontoxic monophosphoryl lipid A increased the magnitude of the immunoglobulin M (IgM) antibody response to type III pneumococcal polysaccharide in young (2- to 4-week-old) mice. This was accompanied by the appearance of significant numbers of IgG1- and IgG3- secreting antibody-forming cells in 4-week-old mice. These findings indicate that monophosphoryl lipid A can be used as an adjuvant to improve the immunogenicity of poorly immunogenic antigens in young, immunologically immature animals.