Human monoclonal antibody against Forssman antigen

Hybrid cells formed between human lymphocytes and mouse myeloma cells produce human immunoglobulin in culture. Stable antibody-producing cell lines can be isolated after multiple cycles of low-density passage, cloning, and continued selection for immunoglobulin production. The origin and characteristics of a hybrid of human and mouse cells is described. This hybrid produces high concentrations (8.3 micrograms per milliliter) of human immunoglobulin M reactive with the terminal disaccharide of the Forssman glycolipid. These findings point to the potential use of human-mouse hybrid cells as a source of human monoclonal antibodies for therapeutic and diagnostic purposes.

An auto-reactive A-like ovarian determinant distinct from xeno-reactive A-like structures

The "natural" anti-A antibody of the mouse is an autoantibody due to the age-dependent appearance of an A-like auto-reactive determinant, which is predominantly displayed by ovarian tissue and probably occurs in other tissues below the level of detection. The present study shows that this determinant is distinct from murine structures which react with xenogeneic anti-A antibody, and that it does not involve the widespread heterogenetic (Forssman-type) A-related specificity. Whereas xeno-reactive A-like structures, which combine with the human "natural" anti-A antibody, are exhibited by several murine tissues and Forssman-type structures by all of them, the murine "natural" anti-A antibody solely reflects the autoantigenic power of the particular determinant discovered in ovarian tissue. This determinant, which undergoes a unique genetic regulation, is present in both the ovary of the C57BL/10 inbred mouse and that of the NMRI outbred mouse and may thus represent a common murine component.

Aminopropyl silica gel as a solid support for preparation of glycolipid immunoadsorbent and purification of antibodies

Aminopropyl silica gel was prepared from porous silica gel and was used as a solid support for immunoadsorbent in the purification of anti-glycolipid antibodies. For neutral glycosphingolipids, a carboxyl function was generated by oxidation of the olefinic double bond of the sphingosine moiety, whereas for gangliosides the carboxyl group of sialic acid was used to couple with aminopropyl silica gel in the presence of a carbodiimide. These compounds were used for purifying anti-glycolipid antibodies from serum of immunized rabbits. The antibodies bound to the su-strate were released by 2 M potassium thiocyanate and their immunological properties were studied. Aminopropyl silica gel may be preferred over conventional organic solid supports for the following reasons: 1) faster flow rate; 2) higher capacity; 3) easier handling; 4) more economical; and 5) lower susceptibility to microbial attack.

Complement-dependent cytotoxic antitumor antibody. II. Quantitative determination of cell-bound immunoglobulin M1

A method for the quantitative determination of rabbit IgM bound to cell surfaces has been developed. This method was based on the ability of goat IgG specific for rabbit IgM heavy chains to bind 125I-labeled protein A when bound to the antigen. With the use of this technique the production of specific IgM antitumor antibodies in New Zealand White rabbits after immunization with guinea pig hepatoma cells line-1 and line-10 was followed. Differences in the production of IgM were observed between the different bleedings from rabbits immunized with line-1. No significant IgM antibody was produced following immunization of rabbits with line-10 tumor cells. This indirect method for determining IgM on the cell surfaces was objective, easy to perform, and detected complement-fixing and noncomplement-fixing antibodies. In addition, this technique could be applied to quantify other components on the cell surface for which a suitable specific antibody was available.

Immune phagocytosis in murine malaria

Spleen macrophages from Plasmodium berghei-infected mice are more efficient in the ingestion of parasitized reticulocytes than spleen macrophages obtained from normal animals. Other indications of spleen macrophage activation detected during malarial infection are enhanced macrophage spreading and increased phagocytosis of opsonized and nonopsonized sheep erythrocytes (E). Peritoneal macrophages are not activated to a significant degree. The appearance of antibodies directed against Forssman antigen, but not to other erythrocyte antigens, is also a feature of this infection and explains the ingestion of unsensitized E by spleen macrophages of the diseased animals. The recognition and ingestion of parasitized reticulocytes by infected mice in mediated by cold-agglutinin type immunoglobulins that appear during P. berghei infection and can be blocked by the Fc-binding protein A from Staphylococcus aureus. In advanced stages of the disease, the serum of infected animals inhibits phagocytosis, probably because of the high level of circulating immune complexes. Thus, the clearance of malaria parasites is regulated by several elements of the immune system, in addition to levels of specific antimerozoite antibodies, including the amount of antibodies bound to reticulocytes, the presence of circulating immune complexes, and the degree of macrophage stimulation.

Self-nonself concept for cancer and diseases previously known as "autoimmune" diseases (illegitimate transferases/plasma exchange)

The illegitimate glycosphingolipid antigens of the P blood group system and of the Forssman (Fs) tissue antigen in adenocarcinoma which are foreign to the host suggest the self-nonself concept which applies also to numerous other diseases such as rheumatoid arthritis, lupus, gluomerulonephritis, and idiopathic acute hemolytic anemia. In the presence of the glycosphingolipid antigens such as ABO, P, and Fs, the normal serum of the homozygote recessive precursor contains antibodies for the missing antigen(s). The expected antibody to the Fs antigen was present in about 75% of normal men and women. In cancer sera, the incidence of anti-Fs was decreased to about 35-40%. On testing the normal population anti-Fs was present in 90% of the sera in the youngest group, and this value gradually diminished in the older groups; the incidence of the antibody in the 70-year age group was to about 60%. The rate of loss of anti-Fs with increasing years appears to parallel the gradual loss of anti-A and anti-B isoagglutinin titers. This phenomenon may be associated with the gradual diminution of protein synthesis with aging or the continuous accumulation of soluble immune complexes in the serum, or both. It is suggested that the self-nonself concept is also the basis for the pathogenesis of rhematoid arthritis, lupus erythematosus, idiopathic acute hemolytic anemia, and numerous other conditions classified as "autoimmune" diseases. Some of these diseases are induced by viruses or drugs or both. When a virus or drug attaches itself to the membrane of a tissue cell, the self is converted to nonself which, in rheumatoid arthiritis, alters its self Ig to nonself Ig.

Correlation between the ability of tumor cells to incorporate specific fatty acids and their sensitivity to killing by a specific antibody plus guinea pig complement

Line-1 diethylnitrosamine-induced guinea pig tumor cells can be rendered sensitive to killing by rabbit anti-Forssman IgM antibody plus guinea pig complement (GPC) or antitumor antibody plus GPC following prolonged incubation (17 hr ) of the cells with one of several metabolic inhibitors. Compared to control cells, these cells have been shown to be inhibited in their ability to incorporate fatty acids into complex cellular lipids, which suggested that lipid synthesis is of fundamental importance for the ability of the tumor cells to resist humoral immune killing. In this study, drug-treated cells that were rendered sensitive to killing by anti-Forssman antibody plus GPC, but not antitumor antibody plus GPC, were inhibited in their incorporation of saturated (palmitic or stearic acid), but not an unsaturated, fatty acid (linoleic acid). These data suggested that the fatty acid composition of specific lipids may also be important for the resistance of these tumor cells to killing by antibody and complement.

Studies on the interaction between protein A and immunoglobulin G. I. Effect of protein A on the functional activity of IgG

Staphylococcal protein (A (PA) and IgG anti-Forssman immunoglobulin formed complexes that behaved functionally like IgM in their ability to lyse sheep erythrocytes (E) in the presence of whole guinea pig complement (GPC) and to fix purified guinea pig C1. Concanavalin A, a plant lectin that inhibited IgM but not IgG hemolytic activity, inhibited the hemolytic activity of IgG-protein A complexes that behaved like IgM but had no effect on complexes that behaved functionally like IgG. Since Con A is known to bind specifically to glucose and mannose residues, our results suggested that the interaction of protein A with the Fc region of IgG led to exposure of sugar moieties that may participate in complement (C) binding. The production of IgM-like complexes depended on the ratio of protein A to IgG and the empirical formula of these IgM-like complexes was found to be [(IgG)2PA]n. As the ratio of PA to IgG was increased, the resulting complexes tended to behave functionally like IgG but with reduced hemolytic activity and C1 fixing ability. Furthermore, the binding of C1 to EIgG was inhibited by PA and the binding of PA to EIgG was inhibited by C1 indicating that the binding sites for C1 and PA were located near each other or were identical. Our results offer a reasonable explanation for the reported effects of PA or mixtures of PA and IgG in vitro and in vivo.

Forssman glycolipid variants of dog gastric mucosa. Structure of a branched ceramide octasaccharide

A fucose-containing ceramide octasaccharide exhibiting Forssman antigenic activity, and reacting in human H anti-H and anti-A systems, was isolated from water-soluble glycolipids of dog gastric mucosa. Defucosylation of the glycolipid resulted in the loss of H-activity, but had no effect on its Forssman nor blood-group A antigenic activity. The branched structure of glycolipid was identified by partial acid hydrolysis, sequential degradation with specific glycosidases and comparison of the permethylation products of the native and enzyme-degraded compound. The structure of this glycolipid is proposed to be: formula.

125I protein A: applications to the quantitative determination of fluid phase and cell-bound IgG

An improved method for the preparation of 125I-labelled Protein A (125I PA) of high specific and functional activity is described. 125I PA has been used in combination with purified rabbit IgG bound to a solid support to develop a competitive binding assay capable of detecting Protein A or human, rabbit and guinea pig IgG at the nanogram level. An optimal set of assay conditions was established and levels of IgG measured in normal human, rabbit and strain-2 guinea pig serum. 125I PA has also been used to detect IgG anti-Forssman antibody bound to sheep erythrocytes and to line-1 and line-10 tumor cells and as an indirect assay for tumor associated antigen in the ascitic fluid of tumor-bearing guinea pigs.

Studies on the heterophile antibodies of infectious mononucleosis. I. Separation of four antibody populations, one of which contains lymphocytotoxic activity

With the aid of insolubilized immunoadsorbents made with glycoproteins, extracted from cow red blood cells (RBC), and with guinea-pig kidney tissue, heterophile antibody populations of the Paul--Bunnell type and the Forssman type were eluted from infectious mononucleosis sera. Two Paul--Bunnell-type antibody populations were separated on the basis of their affinity for cow RBC antigens. The lymphocytotoxic antibodies in the infectious mononucleosis sera were eluted among the low-affinity Paul--Bunnell antibodies.

On the mechanism of membrane damage by C: exposure of hydrophobic sites on activated C proteins

In previous papers we have presented evidence that peptides from C proteins C5b, C7, C8, and C9 become inserted in the lipid bilayer membranes and form a transmembrane channel. Presumably, this insertion follows exposure of hydrophobic domains by C activation. In the present experiments liposomes were made with 14C-phosphatidyl choline (PC) and Forssman antigen in the bilayer, and with 86Rb+ in the aqueous compartments. When such liposomes were incubated with anti-Forssman antibody (A) and guinea pig serum (GPS) as a source of C, substantially more 14C-PC and 86Rb+ were released than from liposomes treated with A and C4-deficient GPS, or with A and heated C, or with C alone, or with A alone. The specific release of PC was dependent on the dose of C. Prior treatment of GPS with cobra venom factor abolished its capacity to release PC. The release of PC by A and C7-deficient human serum (C7D-HS) was the same as that of GPS alone, i.e., there was no specific release. A and C8D-HS produced much less specific release than A and GPS; addition of purified guinea pig C7 or C8 to C7D-HS or C8D-HS, respectively, restored the PC release to its full extent. Hence, part of the PC removal is mediated by C5b,6,7; the remainder is attributable to C8 and/or C9.

Correlation between lipid synthesis in tumor cells and their sensitivity to humoral immune attack

Prolonged incubation of two antigenically distinct, chemically induced guinea pig hepatomas with relatively high concentrations of chemotherapeutic drugs or metabolic inhibitors increases their susceptibility to killing by antibody and complement. This effect is reversible when the cells are cultured in the absence of the drugs. The drug-induced sensitivity and the ability of the cells to recover their resistance to killing are directly correlated to their ability to synthesize complex lipids.

Water-soluble glycosphingolipids of dog gastric mucosa. Characterization of a branched ceramide heptasaccharide

Two glycosphingolipids, the carbohydrate portion of which consisted of galactose, glucose and N-acetylgalactosamine, have been isolated from the aqueous phase of buffered tetrahydrofuran extract of dog gastric mucosa. The structures of these glycolipids were identified by partial acid hydrolysis, sequential degradation with specific glycosidases and methylation analysis. The structure of glycolipid I (GalNAcalpha1 leads to 3GalNAcbeta1 leads to 3Galalpha1 leads to 4Galbeta1 leads to 4Glc leads to ceramide) was found to be identical to that of Forssman hapten. The branched structure of glycolipid II, as determined by the combination of enzymatic degradation and comparison of the permethylation products of the enzyme-degraded compounds, is proposed to be: See Source.

Effect of concanavalin A on the killing of tumor cells by antibody and complement

Concanavalin A (Con A) was found to inhibit the killing of antibody-sensitized line-1 tumor cells (TA) by guinea pig complement (GPC) but not by human complement (HuC). Other plant lectins (wheat germ, leucoagglutinin, and pokeweed mitogen) were also tested but Con A was the only lectin found to inhibit antibody-GPC-mediated killing. The inhibitory effect of Con A was observed when the GPC was mixed with Con A or when the antibody-sensitized cells were pretreated with Con A (TA-Con A) before the addition of GPC. The effect could be reversed by treatment of such cells with alpha-D-methylglucopyranoside or by incubation at 37 degrees C for approximately 2 hr. Con A appeared to act by preventing the binding of the first component of GPC (GPC1) to antibody-sensitized tumor cells. Differences in the binding of the first component of HuC (HuC1) and GPC1 to TA-Con A suggested that a difference in the binding site for HuC1 and GPC1 might exist. There was no difference in the number of GPC1 molecules fixed to antibody-sensitized sheep erythrocytes (EA) or EA treated with Con A in experiments using the same antibody as used with the tumor cells and the same Con A preparation. It would consequently appear that the inhibitory effect of Con A on the binding of GPC1 to TA is not due solely to an interaction of Con A with the antibody.

Quantitative requirements for C3 to induce Forssman systemic shock and cutaneous hemorrhagic vasculitis in guinea pigs

The requirements of complement (C) to induce systemic and cutaneous Forssman reactions were studied in inbred DHC-BA and Hartley strain guinea pigs. After intravenous injection of Forssman antibody, fatal systemic shock was associated with a marked drop in CH50, C4, and C3 and a lesser decrease in C5 hemolytic activity. Platelet counts and leukocyte counts dropped as well. With the use of the purified low molecular weight factor from cobra venom (CVF) to deplete C3, guinea pigs with less than 1% intravascular C3 were protected from lethal shock. Approximately 1% to 3% C3 activity is required for Forssman cutaneous vasculitis. These results confirm earlier studies that classical complement pathway activation occurs in Forssman shock and demonstrate the exquisite biologic efficiency of C3 in provoking the shock syndrome.

Kinetics of hormone-induced tumor cell resistance to killing by antibody and complement

Line 1, a chemically induced guinea pig hepatoma, is susceptible to killing by anti-Forssman immunoglobulin M antibody and guinea pig complement. When these tumor cells are pretreated with insulin, L-epinephrine, hydrocortisone, or prednisolone, the cells show a marked reduction in their susceptibility to antibody-complement-mediated killing within 15 to 60 min; this effect reverses within 4 hr in the continued presence of hormone. Maximal binding of the hormones to the line 1 cells was observed within 60 min. However, the hormones remained bound to the cells after 4 hr of incubation, suggesting that line 1 cells incubated in the continued presence of hormone revert to the susceptible state despite the persistence of cell-bound hormone. Hormone-treated tumor cells, washed free of hormone and reincubated in hormone-free medium, lost nearly all their bound hormone within 15 to 30 min of washing. These cells, however, remained resistant to antibody-complement-mediated killing for up to 2 hr after washing. Line 1 cells, reverted in the continued presence of hormone, remained susceptible to killing by antibody and guinea pig complement after reexposure to the same, but not to a different, hormone. Hormone-treated cells reverted after prolonged incubation in hormone-free media; however, they were rendered resistant to killing after reexposure to the same hormone. The temporary refractoriness of reverted cells to further hormone stimulation was not due to an inability of the cells to bind hormone.

Antigenic similarity between simian virus 40-induced surface and fetal antigens in hamster

The tumor-associated cell-surface antigen (TSSA) on simian virus 40 (SV40)-transformed hamster cells was studied serologically by a complement-dependent cytotoxicity test. An antiserum was obtained from guinea pigs inoculated with SV40-transformed hamster cells. The serum was cytotoxic to SV40-transformed hamster cells after absorption with 15-day hamster embryo cells, hamster cells transformed either by polyoma virus or adenovirus 12, various tissues of hamster origin (brainliver, spleen, and kidney), or sheep red blood cells. These results indicated that the major TSSA induced specifically by SV40 was similar or identical to the antigen present during early stages of embryogenesis.

Inhibition of anaphylactic histamine release by Forssman antiserum. II. Mechanism of inhibition

The mechanism was studied of the inhibitory effect of IgG Forssman antibody on anaphylactic sensitization in the guinea pig lung. Two possibilities were considered to explain the inhibitory effect: either the Forssman antibody-antigen interaction occurred on the mast cell, allowing the F(ab′)₂ portion to interfere with the Fc receptor(s) for anaphylactic antibody; or the interaction took place adjacent to the mast cell allowing the Fc portion to occupy the receptors for anaphylactic antibody. These studies were made possible in part by developing a method for preparing mast cell suspensions from guinea pig lung. The mast cells were viable but released histamine only on treatment with compound 48/80 and not with anaphylatoxin, soluble immune complexes or with active or passive anaphylactic sensitization. Mast cells incubated with Forssman antibody and complement showed no evidence of injury as judged by electron microscopy, suggesting that they did not contain Forssman antigen. The absence of Forssman antigen from mast cells was substantiated further by studies of mixed agglutination and fluorescence microscopy. Also, pepsin digestion of Forssman antibody resulted in a loss of the ability to inhibit the histamine-releasing activity of soluble immune complexes, indicating that the F(ab′)₂ portion alone was not sufficient to sustain the inhibitory process. It was concluded that the inhibitory effect of IgG Forssman antibody was due to union with interstitial Forssman antigen adjacent to mast cells, allowing the Fc portion of the Forssman antibody to irreversibly occupy the mast cell Fc receptor(s) for anaphylactic antibody.

Effect of concanavalin A on the functional activity of hemolytic antibody

Concanavalin A (Con A), either in solution or insolubilized by covalent binding to Sepharose 4B, can inhibit the ability of fluid phase 19S, but not 7S, anti-Forssman antibody to sensitize sheep red cells (E) toward lysis by excess guinea pig complement. The efficiency of 19S antibody is unaffected when E are treated with Con A before sensitization or when antibody sensitized cells (EA) are exposed to the lectin before complement is added. Although whole complement activity is retained on a solumn of Con A-Sepharose, cell bound lectin did not act as a complement fixing antibody. Consistent with this result, there was no difference in the amount of C1 fixed by E and E-Con A, or by EA and EA-Con A.

Metabolically dependent and independent cell surface antigens

In contrast to metabolically dependent tissue-specific cell surface antigens (MDA) which are available for reactions with antibodies only on surfaces of metabolically active cells, the availability of the universally distributed blood group A or Forssman-type antigens on cell surfaces was found to be independent of the metabolic activity of cultured cells. In case of the MDA, cytotoxic reactions were induced by antibodies alone, resulting in a disorganization of the cellular sheet without a significant release of radioactive label. Radioactive release in this cytotoxic reaction was increased by the addition of complement without additionally affecting the degree of cell sheet disorganization. In case of Forssman and blood group A antigens, such morphologically demonstrable cytotoxicity required complement, and the resulting pathology was always accompanied by extensive release of cellular contents. The ability of anti-MDA antibodies to induce cytotoxic reactions in the absence of complement may be related to a vital role of MDA in cellular function.