The development of sensitive and specific radioimmunoassays for leukotrienes

Radioimmunoassays for leukotriene C4 (LTC4) and for leukotriene B4 (LTB4) have been developed. LTC4 was conjugated with thiolated hemocyanin (Keyhole Limpet) (KLH) using 6-(N-maleimido)hexanoic acid chloride as coupling agent. LTB4 was converted to its hydrazide derivative, via the delta-lactone and the hydrazide was similarly coupled with thiolated KLH using 6-(N-maleimido)hexanoic acid chloride as coupling agent. These conjugates were used to consistently raise high titres of anti-leukotriene antibodies in rabbits. 14,15-[3H]-LTC4 was prepared by total synthesis via two routes. 14,15-[3H]-LTB4 was prepared by total synthesis. The assay for LTC4 recognizes LTC4, LTD4 and LTF4, and to a lesser extent, LTE4 with a detection limit of ca. 0.1 pmoles LTC4 per mL of sample. The assay for LTB4 is highly specific and has a similar detection limit.

Delineation of Ia:nominal antigen complementary determinants recognized by T cells in studies of gene complementation in response to insulin

The immune response to beef insulin in mice is controlled by genes in the IA subregion. We have previously shown that B6.C-H-2bm12 (bm12) mice, an A beta gene mutation of B6, have a selective loss of responsiveness to beef insulin, whereas other IAb controlled responses such as (TG)AL and collagen are unchanged. F1 hybrid mice between two nonresponder genotypes Ik and Ibm12 were found to be good responders to beef insulin suggesting functional complementation. In this report, we define the cellular and molecular basis of this complementation by investigating the determinants on Ia molecules and nominal antigen that are recognized by (B10.A X bm12)F1 proliferating T cells. Genetic analyses demonstrated that the Ik region was the only nonresponder genotype that complemented Ibm12, thus restoring responsiveness to beef insulin. More precisely an IAk and not an IEk gene product was found to be responsible for this complementation. Antibody blocking studies furthermore showed that the A alpha b:A beta k hybrid Ia mediated the response to beef insulin in (B10.A X bm12)F1 mice. Clonal analyses of the response to beef insulin in these F1 mice confirmed these conclusions, because the insulin-specific response in all 21 F1-T cell clones studied thus far was found to be dependent upon presentation via the A alpha b:A beta k hybrid Ia molecule. Dissection of the antigenic specificity of the F1-T cell clones demonstrated recognition of at least two insulin determinants, one A-loop (A8-A10) associated and the other non-loop (A4 or B chain) associated. Therefore these studies identify the molecular and antigenic basis of the Ir gene complementation seen in the response to beef insulin of (B10.A X bm12)F1 hybrids.

Measuring leukotrienes of slow reacting substance of anaphylaxis: development of a specific radioimmunoassay

Rabbits were immunized with leukotriene C4 (LTC4) coupled to thiolated keyhole limpet hemocyanin (KLH) by using 6-N-maleimidohexanoic acid as a spacer molecule. Immune serum was obtained with 7.9 nmol of LTC4-specific immunoglobulin per milliliter and a mean association constant of 2.1 X 10(9) M-1. A radioimmunoassay was developed that detected 0.1 pmol of LTC4 per 1-ml sample. LTD4 and LTE4, three isomers of LTC4, the sulfones of LTC4, LTD4, and LTE4, and one isomer of LTD4 reacted to varying degrees in the assay. A number of other structurally related compounds, such as LTB4 and 5-HETE, did not react. Conditions were established to determine LTC4 levels in human plasma without loss of LTC4 during sample preparation and without the need for extraction procedures before the measurement of LTC4.

Measuring leukotrienes of slow reacting substance of anaphylaxis: development of a specific radioimmunoassay

Rabbits were immunized with leukotriene C4 (LTC4) coupled to thiolated keyhole limpet hemocyanin (KLH) by using 6-N-maleimidohexanoic acid as a spacer molecule. Immune serum was obtained with 7.9 nmol of LTC4-specific immunoglobulin per milliliter and a mean association constant of 2.1 X 10(9) M-1. A radioimmunoassay was developed that detected 0.1 pmol of LTC4 per 1-ml sample. LTD4 and LTE4, three isomers of LTC4, the sulfones of LTC4, LTD4, and LTE4, and one isomer of LTD4 reacted to varying degrees in the assay. A number of other structurally related compounds, such as LTB4 and 5-HETE, did not react. Conditions were established to determine LTC4 levels in human plasma without loss of LTC4 during sample preparation and without the need for extraction procedures before the measurement of LTC4.

The immune response to insulin in man. Interaction of HLA alloantigens and the development of the immune response

In both mice and guinea pigs, the immunologic response to insulin has been demonstrated to be under immune response (Ir) gene control. In the present study, we have attempted to identify Ir genes to insulin in man by correlating HLA allotype with immunologic response to insulin. Three groups of patients were studied: (1) 117 diabetic patients with a history of exaggerated immunologic response to insulin (insulin allergy, resistance, or systemic reactions); (2) 95 insulin-taking diabetics without clinically significant immune response; and (3) 109 nondiabetic controls. Determination of HLA alloantigen frequencies in the “insulin allergic” population and the nonallergic diabetics revealed only modest increases of HLA-Bw44 (29% versus 16%, P < 0.05) and -DR7 (28% versus 15%, P < 0.05). Studies of linkage disequilibrium, however, revealed interesting associations involving HLA-A2, -Bw44, and -DR7 in the diabetic with insulin allergy that were not present in the nonallergic diabetic. Combinations of any two or all three of these antigens were observed in 39% of diabetics with insulin allergy but in only 3% of nonallergic diabetics. An intermediate frequency (23%) was observed in the normal population. Thus, if an individual with any combination of HLA-A2, -Bw44, and -DR7 develops diabetes and receives insulin therapy, there is over a 90% probability he will exhibit a clinically significant immune reaction to insulin (calculated relative risk = 20.6). These data suggest that in man, as in the mouse, the immune response to insulin is under genetic control, but this may involve interactions of several genes in the major histocompatibility (MHC) complex, or a locus in linkage with these genes that is not measured by current techniques.

Regulation of immune response by preadministration of cells briefly pulsed with antigen in vitro. I. Suppression of IgE antibody response by antigen pulsed spleen cells

The intravenous administration of syngeneic spleen cells (SPCs) briefly pulsed with antigen in vitro, results in a profound state of IgE antibody unresponsiveness. In Balb/c mice, the primary response of anti-DNP, anti-beef insulin and anti-ovalbumin IgE antibody is completely suppressed by the administration of antigen-pulsed spleen cells, 1 X 10(7), 5 X 10(7) and 1 X 10(8), respectively. This suppression is antigen specific and effects both primary and secondary immune responses. Furthermore, the immune response to dinitrophenylated Keyhole limpet hemocyanin (DNP-KLH) is most extensively suppressed by DNP-KLH pulsed SPCs, intermediately suppressed by KLH-pulsed SPCs and minimally suppressed by dinitrophenylated mouse gamma globulin or dinitrophenylated mouse serum albumin pulsed SPCs. Suppressing directly cells specific for hapten and carrier, hapten carrier protein pulsed SPCs would caused the additive suppressive effect. The suppression is induced strongly by the intravenous administration of antigen pulsed spleen cells, slightly by the subcutaneous administration and is not induced by the intravenous administration of antigen solution in phosphate buffer saline. This suppression may be mediated by either of two different mechanisms: one of them is responsible for the immediate tolerance which is induced without any suppressor cells 1 day after the administration of antigen pulsed SPCs, and the other is responsible for the suppression transferred by suppressor cells or factors to normal mice 7 days after the administration of antigen pulsed SPCs. This method in which IgE antibody response is suppressed by the administration of cells briefly pulsed in vitro with antigen, provides a powerful tool to analyze the first step of antigen specific suppression developed in vivo by conventional antigens.

Selective loss of antigen-specific Ir gene function in IA mutant B6.C-H-2bm12 is an antigen presenting cell defect

Immune responses to several soluble antigens were compared between B6.C-H-2bm12 mutant and wild-type B6 mice by using a lymph node T-cell proliferation assay. B6.C-H-2bm12 mice failed to respond to beef insulin whereas other IA gene-controlled responses, such as response to poly(L-Tyr, L-Glu)--poly(DL-Ala, L-Lys) and collagen, were indistinguishable between mutant and wild-type mice. The responses to multideterminant antigens such as ovalbumin and purified protein derivative of tuberculin were also found to be comparable in B6.C-H-2bm12 and B6 mice, thus indicating that this mutation resulted in a selective loss of the ability to respond to a certain antigen(s)--e.g., beef insulin. Populations depleted of adherent cells have been used to examine the mechanism by which Ia molecules mediate Ir gene control of antigen recognition. We show that the nonresponsiveness to beef insulin in the mutant mouse is the result of defective antigen presentation. In addition, we find that F1 hybrids between two nonresponders--B6.C-H-2bm12 and B10.A or B10.AKM (IAk) mice--become responders to beef insulin, thus demonstrating gene complementation. These findings taken together with other serologic and biochemical studies in the B6.C-H-2bm12 present convincing genetic evidence for the direct association of the A beta polypeptide chain of the Iab molecules with the expression of immune responsiveness to beef insulin. Study of the B6.C-H-2bm12 mouse should provide new insight into the cellular and molecular mechanisms by which Ir genes determine the nature of the immune response.

Immune response gene control of determinant selection. III. Polypeptide fragments of insulin are differentially recognized by T but not by B cells in insulin immune guinea pigs

Synthetic polypeptides corresponding to restricted regions of the B chain of insulin were used to evaluate immune response gene control of guinea pigs immune to native insulin. The amino acids necessary for recall of immune memory were assessed at the level of the T cell by use of peptides 8 to 16 amino acids in length, representative of the amino terminus of the insulin B chain to induce antigen-specific proliferation and help for antibody formation. A single histidine residue in the 10th position of the B chain is critical for T cell activation. In addition, immune response genes operating in the macrophage discern the presence or absence of this residue and activate the appropriate T cell clones. Although receptor V region sharing may exist for T and B cells immune to globular proteins, it cannot be demonstrated by antigen specificity, since T proliferation and generation of T helper cells in response to intact insulin can be elicited by synthetic fragments that do not correspondingly induce antibodies that recognize the native molecule.

Immune response gene control of determinant selection. III. Polypeptide fragments of insulin are differentially recognized by T but not by B cells in insulin immune guinea pigs

Synthetic polypeptides corresponding to restricted regions of the B chain of insulin were used to evaluate immune response gene control of guinea pigs immune to native insulin. The amino acids necessary for recall of immune memory were assessed at the level of the T cell by use of peptides 8 to 16 amino acids in length, representative of the amino terminus of the insulin B chain to induce antigen-specific proliferation and help for antibody formation. A single histidine residue in the 10th position of the B chain is critical for T cell activation. In addition, immune response genes operating in the macrophage discern the presence or absence of this residue and activate the appropriate T cell clones. Although receptor V region sharing may exist for T and B cells immune to globular proteins, it cannot be demonstrated by antigen specificity, since T proliferation and generation of T helper cells in response to intact insulin can be elicited by synthetic fragments that do not correspondingly induce antibodies that recognize the native molecule.

I-A mutation resulted in a selective loss of an antigen-specific Ir gene function

The immune responses to several antigens were compared in the I-A mutant mouse strain B6.C-H-2bm12 and the wild-type strain C57BL/6. With a lymph node cell proliferation assay, the response to two of these antigens, beef insulin and (TG)A-L, was demonstrated to be controlled by a gene in the I-Ab region. B6.C-H-2bm12 mice failed to respond to beef insulin, while their responses to (TG)A-L, DNP-OVA and PPD were comparable with those of the wild-type strain C57BL/6. Taken together with previous studies, these data suggest that the product of a single pleiotropic I-A gene, an Ia molecule, functions as a histocompatibility, Ia, and MLR antigen, as well as a necessary component for Ir gene function. Furthermore, the data reported here demonstrate that Ia molecules have multiple functional "Ir determinants," one of which has been altered in the B6.C-H-2bm12 mutant. The B6.C-H-2bm12 mice, therefore, represent a powerful analytical tool for the understanding of the cellular and molecular basis for Ir gene control of the immune response.

Macrophage-lymphocyte interaction and genetic control of immune responsiveness

We have reviewed briefly some of the diverse functions of macrophages in the immune response. Clearly, this population of cells interact physically with lymphoid cells, are required for activation of T cells, and process various protein antigens. Finally, we have studied the immune response to insulin in order to unify these previous data in such a way to demonstrate the active role of macrophages in the regulation of the immune response. The function of the Ir gene in the guinea pigs appears to be an intramolecular selection of discrete regions within the antigen for recognition by the T cell. The data presented suggest that this function operates at the level of the macrophage.

Determinant specific suppression of antigen-induced T cell proliferation in the guinea pig. II. Determinant specific suppression of in vitro T cell responsiveness parallels a selective suppression of anti-hapten but not anti-carrier antibody responses

Using an antigen of defined physical structure with precisely mapped immunogenic sites, we asked whether those molecular sites previously shown to be critical for immune response gene-mediated initiation of T cell proliferation and T help correspond to the same molecular regions capable of inducing antigen-specific suppression of T cell proliferation and antibody production. Inbred strain 2, 13, and 2 x 13 F1 hybrid guinea pigs were immunized with various species variants or fragments of insulin adjuvant before subsequent immunization with antigen in complete Freund's adjuvant. Analysis of the patterns of depressed T cell responsiveness showed a striking correspondence to the Ir gene-dependent mechanism that controls the recognition of discrete regions within the insulin molecule observed in T cell help in antibody production. In addition, suppression of carrier-specific T cells parallels suppression of anti-hapten antibody responses when hapten is presented on the suppressed carrier without a concomitant suppression of the anti-carrier antibody response.

Determinant specific suppression of antigen-induced T cell proliferation in the guinea pig. I. Quantitation of suppressed antigen-specific T cell responses as a consequence of prior exposure to antigen in incomplete Freund's adjuvant

We have asked whether a correlation exists between T cell proliferation and the in vivo suppression of delayed type hypersensitivity observed after administration of antigen in incomplete Freund's adjuvant before exposure to antigen in complete Freund's adjuvant. We find that in vivo suppression is indeed paralleled by diminished in vitro responsiveness to the immunogen. Suppression of T cell proliferation is antigen-specific, dependent upon prior immunization of antigen in IFA, and can be transferred adaptively into unprimed but not primed animals by lymphoid cells from actively suppressed syngeneic donors.

Determinant specific suppression of antigen-induced T cell proliferation in the guinea pig. II. Determinant specific suppression of in vitro T cell responsiveness parallels a selective suppression of anti-hapten but not anti-carrier antibody responses

Using an antigen of defined physical structure with precisely mapped immunogenic sites, we asked whether those molecular sites previously shown to be critical for immune response gene-mediated initiation of T cell proliferation and T help correspond to the same molecular regions capable of inducing antigen-specific suppression of T cell proliferation and antibody production. Inbred strain 2, 13, and 2 x 13 F1 hybrid guinea pigs were immunized with various species variants or fragments of insulin adjuvant before subsequent immunization with antigen in complete Freund's adjuvant. Analysis of the patterns of depressed T cell responsiveness showed a striking correspondence to the Ir gene-dependent mechanism that controls the recognition of discrete regions within the insulin molecule observed in T cell help in antibody production. In addition, suppression of carrier-specific T cells parallels suppression of anti-hapten antibody responses when hapten is presented on the suppressed carrier without a concomitant suppression of the anti-carrier antibody response.

Determinant specific suppression of antigen-induced T cell proliferation in the guinea pig. I. Quantitation of suppressed antigen-specific T cell responses as a consequence of prior exposure to antigen in incomplete Freund's adjuvant

We have asked whether a correlation exists between T cell proliferation and the in vivo suppression of delayed type hypersensitivity observed after administration of antigen in incomplete Freund's adjuvant before exposure to antigen in complete Freund's adjuvant. We find that in vivo suppression is indeed paralleled by diminished in vitro responsiveness to the immunogen. Suppression of T cell proliferation is antigen-specific, dependent upon prior immunization of antigen in IFA, and can be transferred adaptively into unprimed but not primed animals by lymphoid cells from actively suppressed syngeneic donors.

Genetically restricted immune responses in guinea pigs primed in vivo with antigen-bearing macrophages

Guinea pigs injected intradermally with antigen pulsed macrophages generate a population of immune T cells that proliferate in vitro on second exposure to antigen. T cells from F1 (2 X 13) guinea pigs immunized with DNP-OVA on one parental macrophage respond in vitro only to DNP-OVA on macrophages identical to those used for immunization and not to DNP-OVA associated with the other parental macrophages. These results demonstrate that the immunogenicity of antigen is dependent upon the macrophages used for priming in that, with this approach, strain 2 or 13 guinea pigs immunized with allogeneic macrophages pulsed with antigen do not respond to either allogeneic or syngeneic antigen-bearing macrophages. However, lysates of antigen-pulsed macrophages can still immunize either allogeneic or syngeneic recipient via their own macrophages. F1 (2 X 13) guinea pigs are immunized by insulin B chain pulsed strain 13 macrophages (responder) but not by strain 2 macrophages (nonresponder) suggesting that whether a F1 (nonresponder X responder) guinea pig recognizes antigen bound to a parental macrophage is genetically restricted before immunization to the same extent as the donor parental macrophages used for immunization.

Adherent cell function in murine T-lymphocyte antigen recognition. IV. Enhancement of murine T-cell antigen recognition by human leukocytic pyrogen

A macrophage-dependent, antigen-specific murine T-cell proliferation assay was utilized to examine the role of soluble products of murine and human adherent cells in the activation of T lymphocytes. Highly purified human leukocytic pyrogen, and supernates from both murine and human mononuclear phagocytes-macrophages stimulated the immune T-cell proliferative response to the multideterminant antigens dinitrophenyl-ovalbumin and keyhole limpet hemocyanin. The implications of these studies and the relationship of leukocytic pyrogen to human lymphocyte-activating factor are discussed.

Adherent cell function in murine T lymphocyte antigen recognition. III. A macrophage-mediated immune response gene function in the mouse

The I region of the MHC appears to control antigen-specific macrophage-T lymphocyte interaction. The immune response to antigens such as Gl phi 9 are under control of two distinct I subregions, I-A and I-E/I-C. We have asked in a macrophage-dependent, antigen-specific murine T cell proliferation assay whether either or both gene products need be expressed in the antigen-presenting cells. We find that both Ir-Gl phi 9 alpha and beta genes must be expressed and function in the antigen-presenting cell.

Immune response gene control of determinant selection. II. Genetic control of the murine T lymphocyte proliferative response to insulin

The genetic control of the murine T cell proliferative response to insulin was examined. It was found for two responder strains of mice that each recognizes a different determinant on the insulin molecule. H-2b mice recognize a determinant in the A chain loop of insulin whereas H-2d mice recognize a determinant that resides in the B chain, possibly in the last eight amino acids. Using H-2 recombinant strains of mice, the location of Ir gene control of the response to both determinants was mapped to the K region and/or I-A subregion of H-2. The possibility of non-MHC regulation of MHC-controlled immune responses is suggested by studies of recombinant inbred strains of mice.

Macrophage-lymphocyte clusters in the immune response to soluble protein antigen in vitro. VII. Genetically restricted and nonrestricted physical interactions

We have assessed the genetic restrictions on physical interactions between macrophages and central lymphocytes and between central and peripheral lymphocytes in antigen-specific macrophage-lymphocyte clusters with respect to I-region differences of inbred strains 2 and 13 guinea pigs. When using lymphocytes from guinea pigs immunized with DNP-OVA or DNP-GL in CFA, the antigen-specific interaction between central lymphocyte and macrophage requires that both cells be derived from animals syngeneic at the I-region of the major histocompatibility complex. In studies using antigens, the responses to which is under the control of MHC-linked Ir genes, macrophages from the responder, but not from the nonresponder parental strain support cluster formation with responder x nonresponder F1(2 X 13) T cells. In contrast, the physical interactions between central and peripheral T lymphocytes are not restricted by the I-region of the MHC and the peripheral lymphocyte need not be from an animal immune to the antigen used to drive macrophage central lymphocyte interactions.

Adherent cell function in murine T lymphocyte antigen recognition. II. Definition of genetically restricted and nonrestricted macrophage functions in T cell proliferation

The mechanisms by which adherent cells, presumably of mononuclear phagocytic lineage, influence in vitro antigen-specific activation of murine T lymphocytes was examined. Two distinct functions for macrophages could be discerned. One macrophage function is dependent on a soluble factor produced by cultured adherent cells and is most easily studied with complex multideterminant antigens. This factor is neither antigen-specific nor MHC-restricted in its action in that PEC, regardless of haplotype, produce factor in the absence of antigen. A second function, antigen-specific T cell activation, is seen when antigens of more restricted heterogeneity are used, such as those under the control of Ir genes. This latter activity demands identity or partial identity between the antigen-presenting cell and the primed T cell, thus suggesting an additional specific, genetically restricted function for macrophages in in vitro antigen recognition. Whether these adherent cell functions are mediated by all or distinct subsets of cells was not established.