Drug – bio-affecting and body treating compositions – Conjugate or complex of monoclonal or polyclonal antibody,... – Conjugated to proteinaceous toxin or fragment thereof
Reexamination Certificate
1999-03-31
2002-06-11
Saunders, David (Department: 1644)
Drug, bio-affecting and body treating compositions
Conjugate or complex of monoclonal or polyclonal antibody,...
Conjugated to proteinaceous toxin or fragment thereof
C424S186100, C424S188100, C424S189100, C424S195110, C424S196110, C424S208100, C424S227100, C530S402000, C530S403000
Reexamination Certificate
active
06403092
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to the field of immunology and, more particularly, to antigen-&agr;
2
-macroglobulin complexes, the facile and reproducible preparation of antigen-&agr;
2
-macroglobulin complexes, and their subsequent uses, including the enhancement of host immunocompetence and the preparation and administration of vaccines for prevention and treatment of disease states.
BACKGROUND OF THE INVENTION
Antigen Presentation and Immunogenicity
In general, antigens are “presented” to the immune system by antigen presenting cells (APCs), including, for instance, macrophages, dendritic cells and B-cells in the context of major histocompatibility complex molecules (MHCs) which are present on the APC surface. Normally, natural antigens and molecules supplied as immunogens are thought to be taken up and partially digested by the APCs, so that smaller pieces of the original antigen are then expressed on the cell surface in the context of MHC molecules.
It is also presently understood that T-lymphocytes, in contrast to B-lymphocytes, are relatively unable to interact with soluble antigen. Typically T-lymphocytes require antigen to be processed and then expressed on the cell surface of APCs in the context of MHC molecules as noted above. Thus, T-cells, and more particularly, the so called “T-cell receptors,” are able to recognize the antigen in the form of a bimolecular ligand composed of the processed antigen and one or more MHC molecules. In addition to presenting antigens on MHC molecules, the APC must be activated to express co-stimulatory molecules, such as B7/B1, before effective stimulation of T-cells can occur.
Many epitopes on proteins, including both foreign and endogenous proteins, are generally unrecognized or only weakly recognized by the immune system. These epitopes therefore elicit little or no antibody or other immune response, or at most, only a weak response. It has therefore been difficult, and in some instances, impossible to raise antibodies against such epitopes. In contrast, other epitopes elicit extraordinarily strong immune responses, in some instances, to the exclusion (or partial exclusion) of other epitopes within the same antigen molecule. Such epitopes can be termed “immunodominant.”
A separate problem arises in the preparation and administration of vaccines, and particularly vaccines that present peptide antigens. Traditional methods for preparing such vaccines that present antigens as macromolecules through conjugation to protein carriers or polymerization are often unable to induce cytotoxic T lymphocytes (CTL) response in vivo. In such instances an adjuvant is usually added. Use of an adjuvant in the immunizing protocol has the advantage of enhancing the humoral response but has mixed results in priming specific CTL response. Unfortunately, popular adjuvants used in laboratory animals, such as Freund's complete adjuvant, are too toxic and unacceptable for humans. Ideally, protection against viral infection is best provided by both humoral and cell-mediated immunities, including long-term memory and cytotoxic T cells.
For example, the human immunodeficiency virus (HIV), the etiologic agent most closely associated with the acquired immunodeficiency syndrome (AIDS), has become an important objective for various vaccine developments. The predominant vaccine strategy has focused on the use of the envelope protein antigens gp120 and gp160 of HIV-1 produced by recombinant DNA technology. However, the full promise of their use in vaccines cannot presently be realized unless they are administered along with an effective adjuvant.
Enhanced Antigen Presentation
The targeting of antigen (abbreviated Ag) to APC has been extensively studied in vitro and in vivo [For review see (1, 2)]. Techniques that have been used include encapsulating Ag into liposomes (3, 4), crosslinking Ag to antibodies directed against surface proteins (5-9), and forming immune complexes for recognition by FcR (10). A complementary approach of decorating B cell surfaces with mAb recognizing a particular Ag also conferred enhanced ability to present that Ag (11). The capacity for Ag uptake by different APC appears to correlate with efficiency of presentation (12), although Ag focusing or intracellular signaling may also contribute. In general, targeting of Ag to the APC surfaces appears to enhance the immune response.
While B-cells possess specific receptors, surface Ig, for capturing the Ag they present efficiently (13,14), macrophages and other non-B cell APCs must utilize other mechanisms. These may include phagocytosis of particulate or cellular Ag and enhanced endocytosis of opsonized Ag or immune complexes. Yet, the efficient uptake and presentation of soluble Ag by these non-B cell APCs in naive animals is not fully understood. A receptor-mediated process might be involved.
Among the APCs, the macrophages are of particular interest by virtue of the central role that they play in the regulation of the activities of other cells of the immune system. Macrophages act as effector cells in microbial and tumor cell killing as well, and are believed to secrete numerous cytokines that orchestrate many of the diverse aspects of the immune response. The ability of macrophage to regulate a range of immunologic events is in part a function of their expression of Ia surface antigens. The expression of membrane Ia antigens is essential for the induction of specific T cell responses to antigens (15).
The effective internalization and processing of diverse proteins forms a central issue in antigen presentation by macrophages. The immune system must balance the capacity for interacting with vast numbers of dissimilar molecules with the requirements for efficiently responding to very low amounts of Ag. Although macrophages are able to sample their environments through pinocytosis, a need for more efficient means of internalization, such as a receptor-mediated system, has been suggested (16). The targeting of Ag to surface receptors on macrophages or B-cells, either by artificial crosslinking or by exploiting membrane Ig, enhances the efficiency of presentation (1,16,17); however, a naturally occurring antigen presentation system in macrophages has not yet been identified.
The &agr;-Macroglobulin Family of Proteins
The &agr;-macroglobulins and the complement components C3, C4, and C5 comprise a superfamily of structurally related proteins. The &agr;-macroglobulin family includes proteinase-binding globulins of both &agr;
1
and &agr;
2
mobilities. The most extensively studied &agr;-macroglobulin is human &agr;
2
-macroglobulin (&agr;
2
M), a large tetrameric protein capable of covalently binding other proteins (19-27) and targeting them to cells bearing the &agr;
2
M receptor (27-30). Although size and charge may affect the extent of binding, &agr;
2
M can incorporate proteins bearing nucleophilic amino acid side chains in a relatively non-selective manner. This rapid covalent linking reaction is restricted, however, to a window of time initiated by proteinase-induced conformational change, during which an internal thioester on each subunit becomes susceptible to nucleophilic substitution (20,21,31). Thus, &agr;
2
M, C3 and C4 are evolutionarily-related thioester-containing proteins that undergo conformational and functional changes upon limited proteolysis (32,33), resulting in possible formation of thioester-mediated covalent bonds with targets such as proteinases, cell-surface carbohydrates or immune complexes, respectively.
Human &agr;
2
-macroglobulin (&agr;
2
M) is an abundant protein in plasma (2-5 mg/ml). It consists of four identical subunits arranged to form a double-sided molecular “trap” (34). This trap is sprung when proteolytic cleavage within a highly susceptible stretch of amino acids, the “bait region,” initiates an electrophoretically detectable conformational change that entraps the proteinase (35). The resulting receptor-recognized &agr;
2
M is efficiently internalized by macrophages, dendritic cells, and other cells t
Grøn Hanne
Pizzo Salvatore
Duke University
Klauber & Jackson
Saunders David
Tung Mary Beth
LandOfFree
Immune response modulator alpha-2 macroglobulin complex does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Immune response modulator alpha-2 macroglobulin complex, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Immune response modulator alpha-2 macroglobulin complex will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2968414