Antigen retention in joint tissues in antigen-induced synovitis

In the rabbit model of antigen-induced arthritis the duration and mechanism of antigen retention were investigated. The tissue half-life of retained antigen in descending order was meniscus (141 days), articular cartilage (31 days), ligaments (17 days), synovium (8 days) and synovial fluid (4 days). The retention of antigen in collagenous tissue was very firm. Perturbant solutions were used to study the binding of antigen to menisci, and only 6 M guanidine was effective in removing the antigen. The role of specific antibody was investigated. Antibody was bound to normal menisci, but the Fc portion of the molecule was not critical to the uptake of antibody by collagenous tissue. Finally, the interaction of antigen, antibody, and collagenous tissue was studied. Preformed soluble immune complexes produced three times the retention of antigen alone. Sequential administration of antibody and antigen yielded fifteen times the retention of antigen in the normal rabbit. Therefore, antigen retention in collagenous tissue was due to immune complex formation with specific antibody within the cartilage matrix.

Recovery of immunoglobulin removed from lymphocytic surfaces by proteolysis

The removal of immunoglobulin from the surfaces of human lymphocytes by limited proteolysis has been monitored by radioimmunoassay of the supernatants and immunolabelling of the residual membrane.

Sublethal amounts of papain or trypsin can rapidly remove at least the immunoglobulin Fab regions from both normal and leukaemic lymphocytes.

The Fabμ regions survive the high enzyme: substrate ratios prevailing, and thus are recoverable from the digests.

The interaction of IgE with rat basophilic leukemia cells. I. Evidence for specific binding of IgE

A rat basophilic leukemia cell line originally described by Eccleston et al. (3) has been successfully transplanted into eight Wistar strains and adapted to suspension cell culture without noticeable morphological changes. The cells deplete the reaginic activity of mouse and rat immune sera to an extent roughly equivalent to that reported for normal rat mast cells. Studies utilizing radioiodinated antilight-chain antibodies and radioiodinated partially purified rat IgE indicate that the cells bind IgE to their surface membrane with high specificity. Heating or mildly reducing the rat IgE destroyed its binding activity. The binding is unaffected by the presence or absence of Ca(++) and Mg(++), and is markedly inhibited by reaginic but not by normal rat or mouse serums. The affinity of these cells for human IgE, if present at all, is substantially lower than for rat IgE.

Studies of idiotypic antibodies. Production and characterization of autoantiidiotypic antisera

Rabbits were immunized with a hapten-protein conjugate and sera were collected for 189 days. The antihapten antibodies were purified by affinity chromatography, then the same animal that synthesized the antibody was reinjected with polymerized F(ab')(2) fragments of antihapten antibodies. Sera were collected after autoimmunization and tested by an indirect radioimmunoassay technique for reaction with [(125)I]F(ab')(2) fragments of the original antihapten antibody. Results showed that each individual responded to its own F(ab')(2) and the antisera were specific for antihapten antibodies of that individual. Quantitative allotype assays established the immunoglobulin nature of the labeled test antigen. Inhibition assays showed that the reaction was specifically inhibitable with hapten. The relationship of this system with other idiotypic systems and the possible autoimmune implications of autoantiidiotypic antibodies are discussed.

The molecular basis of self-association of antibodies to IgG (rheumatoid factors) in rheumatoid arthritis

The serum and synovial fluid of many patients with rheumatoid arthritis contain immune complexes composed of immunoglobulin G (IgG). In this study such complexes from one patient are shown to be formed by self-association of IgG-antibodies to IgG (IgG-rheumatoid factors), so that each molecule serves as an antibody as well as an antigen. All F(ab')(2) and Fab' fragments derived from these complexes have antibody binding sites for normal IgG. Due to a high association constant in the formation of a cyclic complex by these antibodies, normal IgG is excluded as an antigen. These studies serve as a model for further elucidation of presence of similar immune complexes in the serum and synovial fluid of patients with rheumatoid arthritis.

Synthesis and secretion of immunoglobulin, including IgA, by human tonsil and adenoid tissue cultured in vitro

Cell suspensions (> 90% lymphocytes) from human tonsils and adenoids were washed, filtered through nylon mesh and cultured <i>in vitro. </i>Immunoglobulin (Ig) synthesized by these cultures was quantitated by a [¹²⁵I] Fab assay, and specific IgA was enumerated by a [¹²⁵I] IgA radioimmunoassay. Specificity studies with the IgA assay revealed that it measured serum and exocrine IgA with equal efficiency. Medium from 8 tissues cultured at 37 °C for 72 h contained 3–4 times more Ig and 7–12 times more IgA than was present before culture. Tissue cultures at 24 °C failed to show such increases. Most of the Ig and IgA was produced into culture media during the first 24 h. The IgA protein produced by tonsillar lymphocytes <i>in vitro </i>was 7S monomer IgA by sucrose density ultracentrifugation.

Evidence that the ciliary inhibitor of cystic fibrosis is not an antibody

An inhibitor of ciliary activity is present in the serum of cystic fibrosis (CF) patients and heterozygotes. Fractionation of CF serum has indicated that the inhibitor is associated with the serum IgG fraction. This study compared the activity of the CF inhibitor to that of rabbit antibody preparations directed against oyster cilia. The aim of this investigation was to determine whether the ciliary inhibitory mechanism in cystic fibrosis is related to a typical immunological reaction. Results from experiments utilizing fluorescent antibody techniques demonstrated that an antiserum directed against oyster ciliated epithelium binds immunologically with both human bronchial and oyster epithelial tissue. Results from experiments utilizing immunofluorescent tracing, passive hemagglutination, double immunodiffusion, and papain digestion, however, indicated that the interaction between the oyster cilia and the CF serum inhibitor was not a typical antigen-antibody reaction.

Crystals of phosphorylcholine-binding Fab-fragments from mouse myeloma proteins: preparation and x-ray analysis

Fab-fragments of several phosphorylcholine-binding mouse-myeloma proteins have been prepared by pepsin digestion; two of these, MOPC 167 and McPC 603, gave large crystals from ammonium sulfate solutions. The Fab-fragment from MOPC 167 crystallizes in a hexagonal space group, but does not diffract to a resolution greater than about 8 A. In contrast, McPC 603 crystals (space group P6(3)) diffract to about 2.7 A. An isotopic double-labeling technique was developed that demonstrated that the 603 crystals bind 1 mol of hapten per mol of Fab-fragment, but with a binding constant significantly lower than that observed in solution. The findings indicate that a three-dimensional model of this homogeneous antigen-binding immunoglobulin can be constructed. Accordingly, a search for heavy-atom derivatives and determination of the primary structure are in progress.

Complement fixation by the F(ab')2-fragment of pepsin-treated rabbit antibody

The F(ab′)₂-fragments of rabbit anti-ovalbumin and anti-human serum albumin IgG fixed between 30 and 50 per cent of guinea-pig complement when they were aggregated with the appropriate antigen. The fixation took place at 37° but not at 4° and was completely inhibited by 0.005 M EDTA. The fixation was more efficient when preformed immune aggregates were used rather than allowing the aggregates to form in the fixation mixture. The loss in haemolytic activity was probably due to the fixation of one or more of the late components (C3 to C9) of guinea-pig complement since no significant fixation of the C1 and C2 components could be found. These results may help to explain previous conflicting reports on the ability of 5S antibody to fix complement. The results also suggest that rabbit antibody F(ab′)₂ may fix complement by a pathway which utilizes only the components C3 to C9 thus bypassing the more usual pathway initiated by C1 activation.