A DEMONSTRATION OF ANTIBODY ACTIVITY ON MICROSOMES

THE INTRACELLULAR DISTRIBUTION OF GAMMA GLOBULIN IN A MOUSE PLASMA CELL TUMOR (X5563) AS REVEALED BY FLUORESCENCE AND ELECTRON MICROSCOPY

Ferritin- and fluorescein-conjugated antibody staining has been applied to a study of a mouse plasma cell tumor. The presence of myeloma globulin within cisternae of the endoplasmic reticulum was observed at a stage of the secretory process when the remainder of the cytoplasm was essentially free of labeled globulin. The distribution of ferritin suggested a functional heterogeneity among units of the endoplasmic reticulum. Apparently, progressive accumulation of globulin results in distension of the endoplasmic reticulum and, occasionally, in the appearance of considerable quantities of this secretory protein in the extracisternal cytoplasmic matrix. Participation of the Golgi apparatus in the packaging and release of small quantitites of globulin seems likely. In addition, however, fragmentation of the peripheral cytoplasm with rupture of distended ergastoplasmic vesicles appeared to be another pathway whereby globulin is secreted.

Specific inhibition of wheal-and-erythema responses with univalent haptens and univalent antibody fragments

Wheal-and-erythema responses were studied in normal human volunteers and in a single human subject who is sensitive to the 2,4-dinitrophenyl group. In the normal subjects, reactive skin sites were established by intradermal injection of purified rabbit antibody specific for the 2,4-dinitrophenyl group. In both the active and passively sensitized subjects, wheal-and-erythema was elicited by intradermal injection of a 2,4-dinitrophenyl protein, but not by injection of the same conjugate mixed with certain low molecular weight 2,4-dinitrophenyl haptens or with univalent fragments split by papain from anti-2,4-dinitrophenyl antibody. The latter fragments, unlike intact, bivalent, antibody, do not sensitize normal human skin sites. From these and other observations it is concluded that the wheal-and-erythema response in human skin requires mutually multivalent antigen and antibody. This requirement suggests that multimolecular complexes, containing at least 2 antigen and 2 antibody molecules, are essential in the pathogenesis of this allergic response.

A cytochemical study on the pancreas of the guinea pig. 6. Release of enzymes and ribonucleic acid from ribonucleoprotein particles

Ribonucleoprotein (RNP)¹ particles isolated by DOC treatment from pancreatic microsomes have a RNA content of 35 to 45 per cent of their dry weight. In the analytical ultracentrifuge about 85 per cent of the material has a sedimentation coefficient of ∼85 S. These particles contain amylase, RNase, and trypsin-activatable proteolytic activities which cannot be washed off or detached by incubation in 0.44 M sucrose. The enzymes are released, however, by incubation in the presence of low concentrations of ATP, PP, or EDTA, and high concentrations of IP and AMP. At the same time, and at the same concentrations, ∼80 per cent of the RNA and ∼25 per cent of the protein of the particles becomes also non-sedimentable. The simultaneous addition of Mg⁺⁺ to the incubation medium prevents these losses. This finding, together with the observation that all the Mg⁺⁺ of the particles is released by the same agents, makes it likely that Mg⁺⁺ holds the particles together, and that its removal by the chelators used causes the particles to disintegrate. These findings are discussed in relation to the molecular structure of the RNP particles.

Localization of antibodies in plasma cells by electron microscopy

The localization of antibody in the interior of plasma cells of lymph nodes of rabbits hyperimmunized with ferritin was studied by electron microscopy. The cells were incubated with the antigen (ferritin) which was allowed to penetrate into the cells by suitable methods. Antigen-antibody precipitates were localized in the cisternae of the endoplasmic reticulum and in the perinuclear space. No evident association was found between ferritin and ribosomes or ferritin and outer cell membrane. Cells from control animals immunized with an unrelated antigen, incubated with ferritin, exhibited no labeling. From direct counts of ferritin molecules in plasma cells, a lower limit was evaluated for the antibody concentration in the endoplasmic reticulum (12.2 mg/cm³) and for the total antibody content of a plasma cell (7.0 x 10^–3 gm).

The preparation and some properties of purified antibody specific for the 2,4-dinitrophenyl group

Injection of rabbits with Freund's complete adjuvant containing bovine γ-globulin substituted to near saturation with dinitrophenyl groups leads to the production of large amounts of antibodies specific for the 2,4-dinitrophenyl substituent. These antibodies can be isolated from sera in satisfactory yield (40 per cent) and in a high state of purity (90 per cent specifically precipitable). Hapten dissolution, which was used to screen haptens for their potential usefulness as specific reagents in the purification procedure, provides a means for evaluating, in relative terms, antibody-hapten affinities (in competition with antigen).

Differentiation of lymphoid cells: the non-mitogenic induction of immunoglobulin production by thymus cell extract and thymus cell culture filtrate

The cell-free medium in which thymocytes have been cultured (filtrate) as well as sonic lysates of thymocytes (extract) enhance immunoglobulin production when added to spleen cells during tissue culture. In spite of the requirement for foetal calf serum in the culture medium, production of the enhancing factor in thymocyte culture filtrates occurred even in the presence of a variety of metabolic inhibitors including NaN3, puromycin and hydroxyurea. Although DNA synthesis is required as a prelude to the induction of immunoglobulin production, two lines of evidence indicate that the enhancement produced in response to filtrate and extract occurs via a non-mitogenic process. First, neither cell-free agent was mitogenic toward spleen cells. Secondly, the enhancement of immunoglobulin production due to filtrate or extract was observed even in the presence of inhibitors of DNA synthesis. Multiple functions for thymocytes in the induction of immunoglobulin production are indicated by the findings that thymocytes restore immunoglobulin production of anti-thymocyte serum-treated spleen cells, whereas filtrate and extract, alone or in combination, do not have this capability. Furthermore, filtrate and extract failed to enhance the induction of DNP-group-specific antibody production by cells incubated with DNP-protein, but filtrate and extract could partially restore anti-DNP antibody production of such anti-thymocyte serum-treated cells. The role of thymocytes, filtrate and extract in the antigen-independent and the antigen-dependent induction of immunoglobulin production is discussed.

The absolute requirement for T-cells in the induction of IgM-secreting cells, in vitro

Anti-rabbit thymocyte antibody can totally inhibit the induction of IgM production that ordinarily is observed whem lymphoid cells are incubated, in virto, in the absence of added antigen. Univalent as well as bivalent antithymocyte antibody preparations were inhibitory when added to cells before the induction of immunoglobulin production had occurred but not afterwards. Spleen cells that had been treated with antithymocyte antibody and then cultured with thymocytes for 72 hours exhibited an enhanced inducttion of immunoglobulin production. Untreated spleen cells also showed this property, although both untreated lymph node cells and lymph node cells treated with antithymocyte antiboyd did not respond to thymocytes. The enhancement of the induction of immunoglobulin production by lipopolysaccharide was found to be T-cell dependent as judged from studies using antithymocyte antibody.

Synthesis and secretion of gammaglobulin by lymph node cells: the acquisition of carbohydrate residues of immunoglobulin in relation to interchain disulfide bond formation (heavy and light chains-murine myeloma-mannose-glucosamine-galactose)

Acquisition of carbohydrates in the disulfide-linked heavy (H) and light (L) chain molecules of murine myeloma (ADJPC5), i.e., HH, HHL, and LHHL, was investigated. That some mannose and glucosamine residues are acquired by immunoglobulin precursor molecules was demonstrated by the detection of glucosamine and mannose in HH, HHL, and LHHL. In contrast, galactose was observed solely in LHHL molecules, which have an identical electrophoretic mobility to the secreted product. Furthermore, as judged from cells incubated with [(3)H]leucine, the more juvenile molecules HH and HHL were predominant in the rough microsome fraction, whereas LHHL was the principal molecular species in the smooth microsome fraction. Findings of this type were not observed in rabbit lymph node cells. Thus, galactose, as well as mannose and glucosamine, were found in the more juvenile molecule known for this species (HL). Moreover, the ratio of HL:LHHL, as judged from cells incubated with [(3)H]leucine, was about the same in rough and smooth microsomes.

Synthesis and secretion of gamma-globulin by lymph node cells, VIII. Order of synthesis of the interchain disulfide linkages of immunoglobulins

Murine myeloma cells (ADJ-PC-5), incubated in vitro with (3)H-leucine, secrete (3)H-immunoglobulin G as a single molecular species as judged by the migration characteristics of the labeled product on sodium dodecyl sulfateacrylamide gel electrophoresis. However, the fact that some of the interchain disulfide linkages of intracellular immunoglobulins had not been acquired permitted the identification of the following intracellular species: LHHL (identical to immunoglobulin G), HHL, HH, and L (H and L refer to heavy and light polypeptide chains, respectively). Although HH and HHL were readily observed, radioactivity was not detected in the region of the gel where HL would be expected. The time course for the appearance of the intermediates indicates that in these cells the first interchain disulfide bond to be formed occurs between heavy chains. In contrast, the interchain disulfide bonds of immunoglobulins derived from rabbit lymph node cells were acquired in a different order. The principal intracellular species observed were LHHL and HL, whereas HHL and HH were not detectable. These findings indicate that in this species the first interchain disulfide bond to be formed is that between the heavy and light chains of immunoglobulin G.

Immunoglobulin synthesis and secretion. II. Radioautographic studies of sites of addition of carbohydrate moieties and intracellular transport

The subcellular sites of synthesis and route of intracellular transfer of immunoglobulin G (IgG) have been investigated by electron microscope radioautography with precursors used for the polypeptide chain (leucine-(3)H) and for the carbohydrate moieties (galactose-(3)H and glucosamine-(3)H). For this purpose, plasma cells from a mouse myeloma tumor were labeled with appropriate precursors and the distribution of radioautographic grains was determined at the end of the labeling period and after varying times of incubation in unlabeled medium. The results indicated that the polypeptide backbone is synthesized in a region of the cell occupied by the rough endoplasmic reticulum (RER) and is transported from there to the region of the Golgi complex. Galactose is incorporated in IgG primarily at the level of the Golgi complex, whereas the incorporation of glucosamine appears to take place both in the RER and in the Golgi complex. From the Golgi complex, the completed IgG molecules reach the plasma membrane and are discharged extracellularly. The latter route of transport and the mechanism of discharge are not understood but may be mediated via smooth-surfaced vesicles.

Synthesis of gamma G antibody and immunoglobulin on polyribosomes in a cell-free system

Images

The nature of polysomes isolated from spleen cells of rats stimulated by antigen

Images

Two classes of spleen ribosomes with different sensitivities to chloramphenicol

Images

ANTIGENIC PROPERTIES OF MICROSOMES FROM GUINEA-PIG SPLEEN, LIVER AND LYMPH NODES

The antigenic properties of guinea-pig spleen, liver and lymph node microsomes have been studied. These subcellular particles were isolated by differential centrifugation. Ribosomes were prepared by treating the microsomes with sodium desoxycholate. Double-diffusion in agar and immunoelectrophoresis were the principal serological techniques employed. The use of appropriately absorbed as well as unabsorbed antisera has permitted the recognition of spleen-specific antigens associated with membranous elements of the cell. A liver-specific antigen has also been found. Serum protein antigens associated with the micro-somes and a particle-specific antigen associated with ribosomes have been recognized. The microsomes from the three tissues contain the Forssman antigen. No evidence was obtained to indicate that the RNA present functioned as an antigenic determinant.

STUDIES ON ANTIBODY FORMATION: I. RELATIONSHIP BETWEEN NUCLEIC ACIDS AND ANTIBODY SYNTHESIS IN THE PRIMARY RESPONSE IN THE RAT

The nucleic acid and protein contents of the various subcellular fractions of rat spleen homogenates were determined at varying intervals of time following a single intravenous injection of sheep red blood cell membranes. Small differences were recorded in the NA content of the different fractions, as compared with controls. The microsomal fraction was the only one to exhibit significant increases in NA content. The protein content of the various subcellular fractions did not show significant deviations from control values. Antibodies could be eluted from microsomes of spleens of immunized rats by sodium deoxycholate and ribonuclease treatment. A quantitative difference was found in the immune response of the two strains of rats used (R.V.H. and Wistar rats).

STUDIES ON ANTIBODY FORMATION: I. RELATIONSHIP BETWEEN NUCLEIC ACIDS AND ANTIBODY SYNTHESIS IN THE PRIMARY RESPONSE IN THE RAT

The nucleic acid and protein contents of the various subcellular fractions of rat spleen homogenates were determined at varying intervals of time following a single intravenous injection of sheep red blood cell membranes. Small differences were recorded in the NA content of the different fractions, as compared with controls. The microsomal fraction was the only one to exhibit significant increases in NA content. The protein content of the various subcellular fractions did not show significant deviations from control values. Antibodies could be eluted from microsomes of spleens of immunized rats by sodium deoxycholate and ribonuclease treatment. A quantitative difference was found in the immune response of the two strains of rats used (R.V.H. and Wistar rats).