In vitro induction of a primary response to the dinitrophenyl determinant

IgM-bearing B cell affinity subpopulations possess differential antigen sensitivity in rainbow trout

The need for accurate assessments of in vitro generated antibody prompted examination of the effect of antigen on secreted antibody concentrations and affinities. It was found that the antigen concentrations commonly employed for in vitro stimulation were able to significantly compromise IgM titer and affinity estimates in rainbow trout. Specifically, IgM titers were underestimated with the high affinity antibodies being specifically blocked. To remedy this, pulsed antigen cultures were employed, and it was found to reveal more accurate IgM antibody titers and affinity estimates. Additionally, pulsed dose responses provided evidence that high antigen concentrations specifically suppressed high affinity B cell induction. Optimal expression of high affinity antibodies required exposure to lower concentrations of antigen. Each affinity subpopulation appeared to possess a graded sensitivity to each dose of antigen, revealing the complex dynamic for differential IgM-bearing B cell induction that is possible during a response. These results reveal not only the need for antigen removal prior to in vitro antibody secretion, but also the possible role of high zone immunological tolerance on IgM affinity maturation in rainbow trout.

Transduction of binding affinity by B lymphocytes: a new dimension in immunological regulation

To date, immunologists have operated with two primary paradigms governing the antibody response: (1) that affinity maturation is primarily dependent upon antigen-driven selection of both the germline and somatically amended repertoires, and (2) that antibody effector function is isotypically determined. The teleost model now suggests that these classical paradigms should be broadened to incorporate the ability of the B cell to transduce the strength of antigen recognition (affinity) into structural modifications of its antibody product, which, in turn, modulates the antibody's effector function. Although this relationship, thus far, has only been examined and demonstrated in the teleost, we find a number of the individual elements of this structural/functional relationship have been reported for mammalian IgM, which prompts future investigations into its universality. In sum, these findings suggest a heretofore unrecognized feature of B lymphocyte affinity discrimination, which transduces the affinity of antigen recognition into functionally modified antibodies.

Increased activation of antigen-primed or memory B cells by bacterial lipopolysaccharide

Treatment with bacterial lipopolysaccharide elicits the appearance of greater numbers of background antigen-specific plaque-forming cells (PFC) in the spleens of mice previously exposed or primed to subimmunogenic amounts of various non-cross-reacting antigens so as to generate detectable immunological memory. These findings suggest that treatment with lipopolysaccharide results in the activation of increased numbers of antigen-primed or memory B cells in mice previously exposed to antigen.

Structural and functional analysis of spontaneous anti-nitrophenyl antibodies in three cyprinid fish species: carp (Cyrinus carpio), goldfish (Carassius auratus) and tench (Tinca tinca)

High spontaneous anti-trinitrophenyl (TNP) activities were found in three Cyprinid fish species: Carp (Cyprinus carpio), Goldfish (Carassius auratus) and Tench (Tinca tinca). The molecules involved, isolated by affinity chromatography on dinitrophenyl-lysine Sepharose (DNP-lysine-Sepharose), had the main characteristics of a high molecular weight immunoglobulin (IgM-like). Affinity measurements were performed on natural anti-DNP/TNP antibodies isolated from nine individual tench sera, using the inhibition of DNP-T4 bacteriophage inactivation technique. The antibodies analysed were more specific for TNP than for DNP. No activity was found against paranitrophenyl hapten. Affinities were all very low, even for TNP. In the three species, natural anti-DNP/TNP antibodies constitute as much as 11 to 16% of the total immunoglobulin concentration. This high level of nitrophenyl-binding serum immunoglobulins either suggests the existence of a particular regulatory mechanism in fish or reflects a generally low antibody diversity in these species.

Genetic control of T helper cell function in the clawed toad Xenopus laevis

The genetic control of the collaboration between Xenopus T and B cells has been analyzed in vivo using cells from five strains of major histocompatibility complex-defined Xenopus. When carrier (fowl gamma-globulin)-primed T cells and hapten (dinitrophenylated keyhole limpet hemocyanin)-primed B cells differed by minor histocompatibility antigens or by only one haplotype of the major histocompatibility complex, the collaboration was efficient in the sense that large numbers of plaques, low-molecular weight antibodies and high-affinity IgM antibodies could be recorded in the cultures challenged with dinitrophenylated fowl gamma-globulin. However, when T and B cells differed at both alleles of the major histocompatibility complex, lower numbers of plaques were obtained, no low-molecular weight anti-hapten antibodies could be detected, and the IgM antibodies that were sometimes synthesized were of low affinity. This suggests that the major histocompatibility complex, or a gene linked with it, affects the collaboration between Xenopus T and B cells in a way perhaps similar to that described in mammals.

Mechanism of antigen-induced antibody biosynthesis from antibody precursors, the heavy and light immunoglobulin chains

The immediate precursors of antibody molecules, the heavy (H) and light (L) peptide chains of the immunoglobulins, combine with each other by means of disulfide bonds formed by dehydrogenation of their cysteine residues. In the absence of an antigen this process yields the heterogeneous mixture of normal immunoglobulins. Antigens or their processed derivatives (Ag) interfere with this stochastic process by noncovalent combination with complementarily fitting H chains. The (Ag.H)(n) complexes thus formed, owing to the loss of rotational and translational freedom, combine preferentially with those L chains whose V(L) regions have some affinity for the determinants of the antigen molecule. Subsequent release of Ag from the (Ag.H.L)(n) complexes yields free antigen and antibody molecules. Each of the released Ag molecules can be used repeatedly for the same reaction cycle and thus can induce the biosynthesis of a large number of antibody molecules. Any macromolecule, natural or synthetic, that has at least a few polar groups and that can penetrate to the nascent H and L chains can thus act as an antigen. Whereas the structure of the H and L chains is genetically determined and transmitted through the germ line, the process induced by the antigen is a phenotypic phenomenon. The antigen acts in this process as a stereospecific cofactor or regulator of the thiol-disulfide transhydrogenation of the combining H and L chains of immunoglobulins.

Immune reactivity during aging. I. T-helper dependent and independent antibody responses to different antigens, in vivo and in vitro

The immunological status during aging was assessed by measuring the antibody response of the long-lived (C3H/eb X C57Bl/6J)F1 mice to various antigens in vivo and in vitro. In vivo, a decrease in antibody production to DNP and NIP haptenic determinants coupled on to BGG, as well as the response to SRBC, was observed. The decline was more pronounced in the IgG as compared to IgM antibodies. The results were recorded when various parameters such as antigen dose and kinetics of the response, were considered. Reduction of the antibody response was also noted when PVP was employed as immunogen. Similar results were noted when the responses to SRBC and DNP--polylysine were induced and followed in spleen organ cultures. In all of these experimental systems, the peak response was observed in mice 6--12 months old. From then on a gradual decrease was manifested, mice 30--36 months old producing significantly low responses. The results demonstrate that decrease in antibody production is expressed in the isolated spleen tissue in the same manner as in the intact animal. Furthermore, they were interpreted as indicating that the lesion may be at the T helper and the B cell compartments.

Suppression of anti-hapten antibody response in vitro by hapten-carrier conjugates

Production of antibodies was stimulated or suppressed arbitrarily by antigen treatment in vitro of spleens cultured at various time intervals after in vivo immunization. Spleens of mice immunized to the 2,4-dinitrophenyl or (4-hydroxy-3-iodo-5-nitrophenyl)acetyl haptenic determinants produced antibodies in culture when no antigen was applied in vitro. When a conjugate of the hapten to the same carrier employed for priming was given in vitro, an initial reduction of the response was observed, the level of which was dependent on antigen dose. Subsequently, increased amounts of antibodies were measured. In contrast, in vitro exposure to the hapten conjugated to an unrelated carrier resulted in significant reduction of the response for the entire period of the test. This suppressive effect manifested with various carrier proteins (ovalbumin, bovin IgG, bovine and rabbit serum albumin and keyhole limpet hemocyanin), when when applied to cultures in doses which were potentially immunogenic.

Conditions for the development of IgM- and IgG-antibody-secreting cells from primed mouse splenocytes in vitro

A modified Marbrook chamber has been devised and manufactured which will fit inside a standard tissue culture Petri dish. A comparison has been made between Mishell-Dutton and modified Marbrook culture systems with respect to their ability to support an immune response by quiescent memory cells exposed to antigen in vitro. Good culture conditions are maintained for considerably longer in the modified Marbrook cultures and it seems that as a consequence these cultures support a large and reliable IgG response, normally absent or very small in cultures of the Mishell-Dutton type. Ease of manipulation and convenient size make the modified Marbrook system a good prospect for future long-term experiments.

Decidual extracts suppress antibody response in vitro

Extracts of decidual tissue produced in pseudopregnant rats were found to suppress in vitro antibody response to alpha-2,4-dinitrophenyl-polylysine. The peak levels of both the total antibody response and the 2-mercaptoethanol-resistant fraction were reduced. Extracts prepared in a similar manner from uteri of normal untreated or pseudopregnant rats did not exert such an effect.

An improved quantitative plaque assay for lymphocytes bearing antigen-specific cell receptors

An improved method for the determination of the number of lymphoid cells bearing antigen-specific receptors is described. The method is based on the use of hapten-coupled bacteriophage (dinitrophenyl-T4) and detection of lytic plaques formed by the action of DNP-T4 on a target E. coli strain. The method is highly specific (up to 90% specific binding) and can be adapted for use with other antigenic determinants chemically attached to an active bacteriophage.

IgA in secondary anti-hapten responses in vitro

Production of IgA anti-hapten antibodies in vitro was studied in suspension and fragment cultures of spleens from mice immunized with NIP-CG (4-hydroxy-5-iodo-3-nitrophenylacetyl coupled to chicken globulin) a few weeks earlier. IgA anti-hapten production tended to be of much shorter duration than IgG anti-hapten production. IgA produced in fragment cultures had sedimentation coefficients of 9S, 11S, and 13S. 9S IgA anti-hapten was more prominent later during the in vitro response than earlier. In suspension cultures IgM anti-hapten production preceded IgA and IgG anti-hapten production. Very little IgM anti-hapten was seen in fragment cultures, although the responses on a cell-to-cell basis tended to be much higher in fragment than in suspension cultures.

Immune responses to hapten conjugates in vitro

Several functions of the animal body can take place in cell or tissue cultures with almost unreduced efficiency and precision. Functions, where only one cell type is involved, often do so, but also some differentiation steps where interactions between two or more cell types are clearly needed can take place in tissue culture (Saxén et al. 1968).

Most immune responses require collaboration between two or more cell types (Claman, Chaperon & Triplett, 1966; Miller & Mitchell, 1968; Feldmann & Nossal 1972c). Some of them can be easily induced in vitro but others cannot. Even when antibody responses can be induced in vitro their intensity varies a great deal. With some antigens and under some circumstances a response in vitro can be nearly as strong as one in vivo. A crude comparison can be derived from responses in vitro and in vivo to the same antigen, conjugate of hapten NIP and pneumococcal polysaccharide type III (NIP-SIll, Nakamura, Ray & Mäkelä, 1973).

The ontogeny of antigen-specific T cells

Although the fetal lamb is unable to form circulating antiovalbumin antibodies until about 120 days of gestation, ovalbumin-specific helper T cells can be stimulated to function at an earlier age. This would suggest that the critical event responsible for the precise sequential maturation of immunologic competence to different antigens at different developmental stages is not the first appearance of specific receptors on immunocytes. Alternative explanations of this phenomenon are discussed.

Antibody response by cultured spleen fragments from carrier-primed mice to hapten-protein conjugates

Hapten-protein conjugates stimulated very poor anti-hapten responses in mouse spleen fragment cultures from unimmunized mice, whereas hapten coupled to type III pneumococcal polysaccharide or polylysine induced good responses. When the donors of the fragments were primed with the carrier protein, hapten-protein conjugates induced a strong anti-hapten response. Both the true primary and the carrier-primed response in vitro consisted mainly of IgA antibodies of 9-13S. In carrier-primed responses also IgM was produced at the beginning and IgG at the end of those responses.

Inactivation of hapten-modified bacteriophage by antibody: increased sensitivity of the assay in media containing polyethylene glycol

Inactivation of dinitrophenylated bacteriophage T4 by porcine and rabbit anti-dinitrophenyl (DNP) antibodies was studied by the complex inactivation methods. The inactivation titers increased 20-30 times when polyethylene glycol, mol. wt. 6000, was added to the incubation media. Consequently, the detection of dinitrophenylated serum albumin with the modified bacteriophage could be carried out with higher sensitivity upon addition of polyethylene glycol.

Oligomeric IgA: the major component of the in vitro primary response of mouse spleen fragments

The primary antibody response elicited from mouse spleen explants by conjugates of the 3-nitro-5-iodo-4-hydroxyphenylacetic acid (NIP) hapten consisted mostly of the IgA class. Poly-L-lysine, pneumococcal polysaccharide Type SIII, keyhole limpet hemocyanin, and sheep erythrocytes were effective carriers in this system, whereas chicken globulin was not. The anti-NIP response against all of the immunogenic conjugates was detectable in culture media 4 days after explantation and immunization, and reached peak titers by 8-10 days. IgA was identified by sucrose gradient velocity centrifugation in conjunction with the use of a class-specific antiserum. The media collected at 4 days contained low titers of IgM antibody, whereas the peak response at 8 days consisted almost entirely of IgA. The primary response IgA secreted by the spleen fragments was characterized as polymeric by its sedimentation rate through a sucrose gradient, and as polyvalent by its drastically greater avidity for NIP(14)BSA than for free NIP-aminocaproic acid. Its haptenated phage-inactivating activity was abolished by treatment with 0.1 M 2-mercaptoethanol. These experiments indicate that precursor cells existing in the spleen before primary immunization can give rise to production of polymeric IgA.

Specificity of antibodies in amphibian larvae possessing a small number of lymphocytes

Tadpoles of Rana catesbiana, possessing about two million lymphocytes, were immunized with 2,4-dinitrophenyl- and 2,4,6-trinitrophenyl-conjugated bacteria and proteins, and the antibodies produced were studied by inactivation of dinitrophenyl- and trinitrophenyl-conjugated bacteriophages. Crossreactions were determined by inhibition of inactivation of modified phages with the lysine derivatives of 2,4-dinitrophenyl-,2,4,6-trinitrophenyl-, and 4-mononitrophenyl-groups. Antibodies to the two hapten-conjugates differed as significantly from each other in tadpoles as in larger animals. The ability of the small number of lymphocytes in tadpoles to discriminate between structurally similar determinants, and the estimated large number of antibodies required to cover the whole spectrum of antigenic specificities, suggests that an antigen-reactive cell changes specificity during its life time.

The mechanism of antigenic stimulation of primary and secondary clonal precursor cells

Cell transfers to carrier-immunized irradiated mice have permitted an analysis of the in vitro stimulation of clonal precursors of anti-2,4-dinitrophenyl (DNP) antibody-producing cells derived from both immune and nonimmune mice. The results indicate that: (a) carrier-specific enhancement is obligatory for stimulation of primary precursor cells and increases both the size and number of detectable foci derived from secondary precursors. (b) This carrier-specific enhancement is most apparent in the stimulation of precursors of high-affinity antibody producer cells. (c) The antibody produced by primary foci, like that of secondary foci, appears homogeneous. (d) The frequency of clonal precursors in normal spleens is 38% that in spleens from mice 4-8 months after immunization, and the number of such precursors in normal spleens can be reduced fivefold by specific suppression of donor mice with soluble antigen. (e) The average of association constants of primary monofocal antibodies, like that of primary serum antibody produced in carrier-primed mice, is less than 10-fold lower than that of secondary clonal or serum antibody. (f) The affinity of primary monofocal antibodies shows a slight dependence on stimulating antigen concentration; however, a minimum threshold affinity consonant with stimulation is apparent. (g) Free hapten inhibits antigenic stimulation of primary precursor cells at a much lower concentration than is required for the inhibition of secondary precursors. These results are interpreted as indicating that (a) primary stimulation, like secondary stimulation, results from the selective stimulation by antigen of a population of cells differing from one another in their potential antibody product but each having only a single such product; (b) the antigen receptors of primary cells interact with antigen as if they are monovalent while receptors of secondary cells evidence multivalence; (c) antigenic stimulation appears to require both a relatively high affinity of receptors for bound antigen and an interlinking of receptors through such antigen; stimulation is thus seen as resulting from a stabilization of receptors within antigen-receptor aggregates to the cell surface; (d) T-cells appear to serve both in cross-linking antigens and in amplifying the size of stimulated clones.

Induction of immunity and tolerance in vitro by hapten protein conjugates. I. The relationship between the degree of hapten conjugation and the immunogenicity of dinitrophenylated polymerized flagellin

Of many dinitrophenylated (DNP) protein conjugates tested, only DNP conjugated to polymerized flagellin (DNP-POL) (or the structurally related bacterial flagella) elicited a primary anti-DNP response in vitro. Other DNP proteins, such as DNP-monomeric flagellin (DNP-MON), were capable of inducing secondary responses in vitro. The capacity of DNP-POL to immunize spleen cell suspensions devoid of thymus-derived cells was the reason for the greater immunogenicity of DNP-POL, since even large numbers of flagellin-reactive activated thymus cells did not increase the anti-DNP response of normal spleen cells immunized with DNP-POL, whereas the thymus-dependent response to DNP-MON was markedly increased. The capacity of various batches of DNP-POL to immunize normal spleen cells in vitro varied markedly, depending on the number of DNP groups conjugated. DNP-POL with few DNP groups conjugated was immunogenic, but even at very high concentrations did not induce tolerance. In contrast, highly conjugated DNP-POL did not immunize, but readily induced tolerance. DNP-POL with intermediate degrees of conjugation were, like unconjugated polymeric flagellin, capable of inducing both immunity and tolerance. Since DNP-POL immunizes bone marrow-derived lymphocytes (B cells) directly the reduced response was not due to a masking of carrier determinants, necessary for cell collaboration. By using mixed DNP-5-(dimethylamino)-1-naphthalyl (dansyl)-POL conjugates, it was found that the inhibitory effect of a high degree of hapten conjugated was hapten specific. Depolymerization of DNP-POL to DNP-MON, which does not induce primary anti-DNP responses, was excluded by centrifugation analysis and electron microscopy. The relationship of the degree of hapten conjugation on DNP-POL to the capacity to induce tolerance and immunity in B cells has clarified the mechanism of immunological triggering of these cells. A model of the mechanism of "signal" discrimination between immunity and tolerance in B cells, based on these findings, is proposed.

Thymus-derived lymphocytes: humoral and cellular reactions distinguished by hydrocortisone

Lymphocytes derived from the thymus (T cells) take part in the induction of humoral antibody and also effect cell-mediated graft-versus-host reactions. Preliminary treatment of mice with hydrocortisone caused an inhibition of T-cell function in humoral immunity, while enhancing the graft-versus-host reactivity of the same population of spleen cells. This suggests that different types of T cells participate in cellular and humoral immune reactions.