Presence Of Soluble Antigen Research Articles

Functional subsets of human monocytes defined by monoclonal antibodies: a distinct subset of monocytes contains the cells capable of inducing the autologous mixed lymphocyte culture.

The induction of most immune responses requires the close cooperation between T cells and antigen-presenting cells (APC), presumably of monocyte/macrophage (M phi) lineage. To characterize human APC further, we used two monoclonal antibodies, OKM1 and OKM5, to isolate and identify M phi subsets. OKM1 has been described and recognizes cell surface antigens on most M phi and granulocytes. OKM5 recognizes cell surface determinants present on the majority of human M phi but does not recognize other hematopoietic cell types. A small subset of peripheral blood M phi is OKM1-OKM5+. Human peripheral blood E- cells were separated into OKM1+ and OKM1- subsets by a rosetting technique utilizing anti-Ig-coated red cells. The capacity to present self antigens in the autologous mixed lymphocyte culture (AMLC) resided predominantly within the E-OKM1- subset, even if surface membrane Ig-positive cells were eliminated. Similar experiments showed that the ability to stimulate in AMLC was contained in the E-OKM5+ population and in fact resided primarily within the E-OKM1-OKM5+ subset. All of these subsets were able to trigger allogeneic T cells to proliferate. The capacity of these APC subsets to present soluble antigens (mumps, tetanus toxoid) was also examined. The data demonstrated that although the majority of these APC are E-OKM1+, E-OKM1-OKM5+ cells can also present foreign antigen. Taken together, these data suggest OKM1 and OKM5 can be used to isolate two functionally distinct human M phi subsets. One subset (E-OKM1+) is capable of presenting soluble antigens but shows minimal ability to trigger AMLC. The other subset (E-OKM1-OKM5+) can also present soluble antigens but is the predominant subset that can trigger AMLC.

Characterization of formaldehyde-related antibodies encountered in hemodialysis patients at different stages of immunization.

In hemodialysis patients who reuse formaldehyde-sterilized dialysers we found that antibodies agglutinating native NN red cells belonged exclusively to the IgM fraction of immunoglobulins. In the same patients antibodies directed against formaldehyde-altered NN red cells proved to be mainly IgG in addition to IgM. Three stages of formaldehyde-dependent RBC immunization could be distinguished serologically. The production of these antibodies was dependent on the time of hemodialysis treatment. We found antibodies which could bind complement in the presence of soluble antigen. These antibodies are supposed to damage the patient's red cells immediately after contact to minute amounts of formaldehyde during hemodialysis.

Characterization of Formaldehyde-Related Antibodies Encountered in Hemodialysis Patients at Different Stages of Immunization

In hemodialysis patients who reuse formaldehyde-sterilized dialysers we found that antibodies agglutinating native NN red cells belonged exclusively to the IgM fraction of immunoglobulins. In the same patients antibodies directed against formaldehyde-altered NN red cells proved to be mainly IgG in addition to IgM. Three stages of formaldehydedependent RBC immunization could be distinguished serologically. The production of these antibodies was dependent on the time of hemodialysis treatment. We found antibodies which could bind complement in the presence of soluble antigen. These antibodies are supposed to damage the patient’s red cells immediately after contact to minute amounts of formaldehyde during hemodialysis.

The effects of corticosteroids on the antigen presenting properties of human monocytes and endothelial cells

The steroids hydrocortisone and methylprednisolone had a significant inhibitory effect on T lymphocyte response stimulated to proliferation by autologous monocytes preincubated with viral or bacterial soluble antigen. Methylprednisolone also had an inhibitory effect on the stimulatory capacity of antigen-pulsed monocytes, but only at relatively high doses, greater than 10 μg/ml. Hydrocortisone had very little effect even at doses as high as 100 μg/ml. MP also had an inhibitory effect on the stimulatory properties of antigen-pulsed umbilical vein endothelial cells. The inhibition of accessory cell function seen at high doses of methylprednisolone appeared to be due to suppression of the presentation of soluble antigen in immunogeneic form to sensitized T cells.

Evidence that antisera that react with products of the human HLA-DR locus may block in vitro antigen-induced proliferation by inducing suppression.

It is widely recognized that antisera that interact with determinants encoded by the Ia region of the mouse and its counterpart, the DR locus of man, are capable of interfering with the ability of monocytes and lymphocytes to respond in vitro to an antigenic stimulus. Using an in vitro assay that measures antigen-specific proliferation of human lymphocytes, we found that both a heteroantiserum raised in rabbits (anti-P29,34) and alloantisera which recognize determinants encoded for by the human DR locus dramatically block in vitro antigen-specific proliferation. These anti-DR antisera appear to act at the level of the monocyte; monocytes pulsed and washed free of excess antisera fail to promote proliferation in the presence of soluble antigen and untreated T cells whereas identically pulsed and washed T cells respond normally with untreated monocytes. Furthermore, the addition of unpulsed monocytes fails to restore in vitro antigen-specific reactivity. Our data suggest that membrane-bound anti-DR-specific antisera on monocytes is profoundly suppressive, and also suggests simple steric hindrance may not account for all of the observed effects such antisera have on monocyte-T cell interactions.

Major histocompatibility complex-restricted antigen presentation to antigen-reactive T cells by B lymphocyte tumor cells.

Previous reports have demonstrated that accessory cells function to present soluble protein antigens in association with gene products encoded within the I region of the major histocompatibility complex (MHC) to antigen-reactive T helper cells. The biochemical events that occur during antigen presentation are, however, not well-documented primarily because of the difficulties involved in purifying sufficient numbers of homogeneous antigen-presenting cells. In this paper, a number of Ia-positive B lymphocyte tumor lines are shown to be capable of presenting soluble protein antigens to antigen-reactive continuous T cell lines in an MHC-restricted fashion. The characterization of the antigen presentation function of these tumor cells indicates that the tumor cells have many of the functional antigen-presenting characteristics previously thought to be limited to macrophages. These tumor cells should provide a useful model system for determining the biochemical events that occur in antigen uptake and processing as well as for determining the potential interactions between processed antigen and Ia molecules on the plasma membrane of these antigen-presenting cells.

T cell requirements for generation of helper factor(s) in man: analysis of the subsets involved.

Lymphocyte mitogenic factor functions as a nonspecific helper molecule generated from antigen stimulation of T lymphocytes. As such, it induces proliferation of all major lymphocyte subclasses (T, B, and Null cells) and B cell immunoglobulin synthesis. In the present study, the specific T cell subset requirements for LMF production were determined in man. By utilizing the OKT4 monoclonal antibody directed at the human inducer T cell subset, T lymphocytes were separated into OKT4+ and OKT4- subpopulations. The antigen stimulated OKT4+ subset generated LMF in a fashion comparable to the unfractionated T cell population and was itself capable of directly inducing B cell proliferation and antibody production. In contrast, LMF could not be generated from the OKT4-T cell subset although this population accounted for 40% of the unfractionated T cell population. In addition, the OKT4- subset was unable to facilitate B cell differentiation in the presence of soluble antigen. These studies provide the first report of T cell subset restriction for generation of helper factors in man and further stress the importance of the OKT4+ inducer population in regulation of the human immune response.

Immunologic characterization of a granulocytic leukemia of inbred strain 13 guinea pigs: presence of Ia-positive myeloblasts

Membrane markers expressed by a transplantable granulocytic leukemia induced in inbred strain 13 guinea pigs by N-nitroso-N-butylurea have been investigated by serologic and immunochemical methods. Although the leukemic myeloblasts have no detectable surface immunoglobulin or Fc receptors, they have been found to synthesize and express membrane antigens encoded for by the I-region of the major histocompatibility complex. Despite the presence of Ia antigens, these cells do not stimulate allogeneic T lymphocytes in the mixed lymphocyte reaction nor are they able to present soluble antigen to immune T cells. The presence of Ia antigens on immature myeloid cells suggests that these proteins may be important in cellular functions beyond those identified in the cellular immune system.

Immunologic Characterization of a Granulocytic Leukemia of Inbred Strain 13 Guinea Pigs: Presence of la-Positive Myeloblasts

Membrane markers expressed by a transplantable granulocytic leukemia induced in inbred strain 13 guinea pigs by N-nitroso-N-butylurea have been investigated by serologic and immunochemical methods. Although the leukemic myeloblasts have no detectable surface immunoglobulin or Fc receptors, they have been found to synthesize and express membrane antigens encoded for by the I-region of the major histocompatibility complex. Despite the presence of Ia antigens, these cells do not stimulate allogeneic T lymphocytes in the mixed lymphocyte reaction nor are they able to present soluble antigen to immune T cells. The presence of Ia antigens on immature myeloid cells suggests that these proteins may be important in cellular functions beyond those identified in the cellular immune system.

Interleukin 2 in cell-mediated immune responses.

The lymphokine Interleukin 2(IL2) restores T cell responses in a number of in vitro systems where immunogenicity has been compromised. UV irradiation of the stimulating allogeneic cells in a mixed leukocyte culture eliminates the production of cytotoxic T lymphocytes and greatly reduces the DNA synthesis response. IL2 restores both parameters. UV-irradiated stimulators are also unable to induce the normal production of IL2 which is observed in a mixed leukocyte culture. The cytotoxic activity of allogeneically stimulated thymocytes is almost completely lost within 24 hours after removal of IL2 at 5 days, indicating that the lymphokine is continuously required to maintain CTL. Thymocytes in 4-day cultures do not adsorb IL2 unless they are simultaneously activated with a mitogen. Finally, IL2 does not adequately restore a secondary response to the purified protein derivative of tuberculin (PPD) in adherent-cell-depleted cultures, indicating that macrophages, in addition to being required for IL2 production, have other functions. These probably include the presentation of soluble antigens to responding cells.

Studies on Epstein-Barr virus-related antigens. II. Biochemical properties of soluble antigen in Raji Burkitt lymphoma cells.

Biochemical properties of Epstein-Barr virus (EBV)-related soluble antigen in non-producer Raji Burkitt lymphoblastoid cells, assayed by the indirect single radial immunodiffusion (ISRD) test, were investigated. The soluble ISRD antigen retained activity even after exposure to a temperature of 80 degrees C. The antigen was precipitated in 40% saturated ammonium sulfate and ISRD activity was recovered from the precipitate when reconstituted into a solution. Isoelectric focusing and crossed immunoelectrophoretic analyses revealed that the esoelectric point of the ISRD antigen is pH 4.8 with an electrophoretic mobility similar to that of serum alpha-globulin. With Sephadex G-200 or Sepharose 6B gel filtration, ISRD activity was obtained as a single peak which corresponded to the activity absorbing anti-complement immunofluorescence. The molecular weight of the present EBV-related soluble antigen was estimated to be 220,000-2408000 daltons.

Different serological behaviour of three phytoviruses non-degraded and degraded with pyrrolidin

Behaviour of CMV, PVY and BYV was investigated in serological precipitin drop as well as gel diffusion reactions using crude extracts from infected plants and antisera against intact viruses. Gel diffusion reaction of PVY was positively influenced by degradation of viral particles with pyrrolidin while gel tests with CMV and BYV were influenced negatively. Antiserum and antigen titers of CMV, as determined in gel diffusion tests, were 4 to 8 times higher than in drop tests. The titer of PVY antigen, as determined in gel diffusion test, was the same as in drop test. Finally the titer of BYV antigen was 16 times lower in the Ouchterlony tests. On the basis of the ascertained differences in the behaviour of PVY and BYV the pyrrolidin degradation may be recommended for PVY but not for BYV. Diagnosis of PVY or BYV by testing crude extracts from infective sources for the presence of soluble antigen is not successful for the time being.

Lymphoid Cells in Delayed Hypersensitivity II. In Vitro Phagocytosis and Cellular Immunity

Guinea pigs which develop delayed hypersensitivity, as measured by skin test, after intraperitoneal infection with Candida albicans have mononuclear cells (macrophages and lymphocytes) which show migration inhibition in vitro in the presence of soluble antigen. Macrophages from such animals phagocytose in vitro fewer numbers of C. albicans per cell than those of normal animals, and lower numbers of macrophages are phagocytic in vitro. Nevertheless, such sensitized animals have lower numbers of pathogens in their tissues than the controls, after both groups have been challenged. Thus, the result of macrophages from sensitized guinea pigs being less mobile, less phagocytic, and more destructive than those from normal animals may be a more limited spread of the infectious agent throughout the tissues; the animal would seem more resistant.