IgG Fraction Of Serum Research Articles

Adenylate cyclase stimulation and [3H]thymidine incorporation in human thyroid tissues and thyrocyte cultures: the effect of IgG preparation from patients with different thyroid disorders.

Primary cell cultures of normal and adenomatous human thyroid tissues were incubated with TSH or ammonium sulphate precipited IGG fractions (1 mg/ml) of sera from patients with different thyroid diseases (Graves' disease: active n = 7 in remission n = 12; thyroid autonomy n = 39; simple euthyroid goitre n = 15) and were compared to controls (n = 26). [3H]thymidine incorporation in primary thyrocyte cultures demonstrated a typical bell shape curve after incubation with EGF and TSH with a maximal effect at 10-100 microIU/ml. This effect, however, was inconsistent and positive only in 2 of 7 primary cultures. Only TSH positive cultures were used for IgG studies. 16-28% of IGG fractions from sera of thyroid patients caused high (more than X + 5 SD of controls) stimulation of [3H]thymidine incorporation. Dose response curves of IgG fractions of 19 additional patients (Graves' disease in remission n = 15; thyroid autonomy n = 4) showed an increase in [3H]thymidine incorporation at 0.1 mg protein/ml for 10 patients and at low concentrations of 10-5 mg/ml for 5 patients. There was a good correlation (r = 0.72) (P less than 0.0001) between positive findings in TSH-binding inhibition (TBII) and AC-stimulation (TSI) IGG fractions but none between stimulation of [3H]thymidine incorporation and any other thyroid specific immunoglobulin nor thyroid function nor any other available data. Immunoglobulins stimulating [3H]thymidine incorporation differ therefore from TBII and TSI. The growth effect of these immunoglobulins, however, has yet to be determined.

Schistosoma mansoni: interactions of adult parasites with the complement system.

The interaction of the mouse complement system with adult male Schistosoma mansoni was studied by immunocytochemical localization procedures and in-vitro assays for complement mediated tegument damage. Mouse C3 was demonstrated to be associated with the parasite's tegument, but was localized only in the infoldings of the tegument and not on its free surface. Freshly harvested parasites manifested no detectable tegumental modification when incubated in normal mouse serum or in immune mouse serum. However, parasites which had been allowed to lose their adsorbed host components by elution (incubation in serum free media for 3 h at 37 degrees C) were severely damaged by incubation in normal mouse serum, but not by incubation in immune mouse serum. This damage was shown to be mediated by the alternative complement pathway and appeared to be initially limited to the tubercles of the adult male parasite. Tegument disruption could be blocked by pre-incubation of the eluted worms in either immune mouse serum or an IgG fraction of immune mouse serum. An IgG fraction of normal mouse serum did not protect the parasite, and infected mouse serum (IMS) which had been depleted of IgG produced tegument damage equivalent to that observed with normal mouse serum (NMS). The addition of I-IgG to NMS abrogated tegument damage. These data suggest that while adult schistosomes possess surface molecules bearing alternative pathway complement activation sites, these sites are masked by adsorbed host components in vivo. These results further indicate that in the absence of these masking host molecules anti-schistosome IgG may play a role in protecting the adult worm from alternative pathway activation, perhaps by binding to and blocking the activation sites on the tegument associated molecules.

Killing of human cytomegalovirus-infected fibroblasts by antiviral antibody and complement.

Complement-dependent cytolytic antibodies (CyAb) to cytomegalovirus (CMV)-infected fibroblasts were detectable in acute- and convalescent-phase sera from renal allograft recipients (n = 44) and nonimmunocompromised patients (n = 14) with symptomatic CMV infection but not in sera from control donors (n = 75; P less than .001 by Wilcoxon rank sum test). Renal allograft recipients with secondary CMV infection had the highest levels of CyAb activity. Activity closely correlated with the serum antibody titer to CMV membrane antigens (r = .9106 by linear regression analysis) and was present in both the IgM and IgG fractions of human sera. IgG F(ab)2 fragments were inactive, thus implicating the classical pathway of complement activation. Maximal CMV-specific lysis was obtained with target cells expressing CMV late membrane antigens (greater than or equal to 72 hr after inoculation) irrespective of the CMV strain used. Adsorption and cold target inhibition studies indicated that the target antigens for the CyAb response are specific for the plasma membrane of CMV-infected cells and may only partly be shared by the virion envelope.

Autoantibody to the gastrin receptor in pernicious anemia.

We examined serum IgG fractions from 20 patients with pernicious anemia and 25 control subjects for their capacity to inhibit binding of [125I]15-leu human gastrin-17 to parietal-cell-enriched gastric mucosal cells. IgG fractions from six patients reduced gastrin binding by 45.6 +/- 12.2 per cent, as compared with a reduction of 1.8 +/- 0.7 per cent by fractions from the 25 controls. The fractions from these six patients also reduced gastrin-stimulated [14C]aminopyrine uptake by gastric cells (an index of gastric acid secretory activity in vitro) by 50.2 +/- 8.4 per cent (mean +/- S.D.), as compared with 9.2 +/- 4.1 per cent for the controls. IgG fractions from six other patients that did not reduce gastrin binding also inhibited gastrin-stimulated [14C]aminopyrine uptake, by 48.1 +/- 9.1 per cent. These reductions in gastrin binding and aminopyrine uptake were abolished by absorption of the IgG fractions with suspensions of viable gastric mucosal cells but not by absorption with liver or kidney cells. The IgG fractions did not inhibit [3H]histamine binding or histamine-stimulated [14C]aminopyrine uptake. These results suggest that serum IgG from some patients with pernicious anemia contains autoantibodies to the gastrin receptor.

Identification of pemphigus-like antigens expressed by SCaBER cells.

Indirect immunofluorescence revealed the presence of pemphigus-like antigenic activity on SCaBER cell monolayers after incubation with sera from patients with pemphigus vulgaris. In contrast, no fluorescence was observed after incubation of the cells with sera from patients with bullous pemphigoid, systemic lupus erythematosus or healthy individuals. In order to identify this pemphigus-like antigen, the SCaBER cell membrane proteins were solubilized in non-ionic detergent, separated according to their molecular weight by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and electrophoretically transferred to nitrocellulose sheets. After incubation with pemphigus serum followed by 125I-radiolabelled goat anti-human IgG, autoradiography revealed pemphigus antibody binding activity in the 105 Kd region in electrophoretograms of the unreduced SCaBER cell membrane extracts. This pemphigus-like antigen was isolated by affinity chromatography on the Sepharose-linked IgG fraction of sera from patients with pemphigus vulgaris.

Passive Transfer of Arthritis to Mice by Injection of Human Anti-Type II Collagen Antibody

The serum IgG fraction from a patient with seronegative rheumatoid-like arthritis which contained a high anti-type II collagen antibody titer was injected intravenously into mice susceptible to type II collagen-induced arthritis. A mild, transient, inflammatory arthritis was observed in 20 to 25% of the animals, whereas histologic signs of disease were evident in most of the injected mice. Purified human anti-type II collagen immunoglobulin injected into the knee joints of mice was also shown to induce a transient, inflammatory arthritis. Radiolabeled human anti-type II collagen IgG was shown to accumulate in the peripheral joints of mice, and the specificity of the antibody was shown to be similar to the specificity of anticollagen antibody eluted from the joints of mice with collagen-induced arthritis.

Partial characterization of T cell components related to defined V H (V T) markers

Certain antigen-binding surface molecules and factors of T cells possess serological determinants related to immunoglobulin (Ig)-heavy-chain-variable regions (V H). We obtained sufficient quantities (> 100 μg) of homogenous V H-related T-cell molecules (V TM) for biochemical studies from normal murine thymocytes and by growing large quantities of monoclonal T-cell leukemia lines expressing the determinants. A solid phase immune adsorbent prepared from the IgG fraction of rabbit anti-IgT serum was used to isolate V TM from formic acid-solubilized T cells. The V TM from murine thymocytes and T-cell lines had M r of 65,000–68,000. The V TM from distinct cell lines differ by isoelectric focusing and resolution of tryptic peptides indicating clonal restriction. V TM lack conventional light- or heavy-chain-constant region determinants but cross-react with antisera directed against defined V Ha allotypes and J H peptides. The detection of a cross-reaction with a synthetic J H peptide is consistent with recently published data identifying J H-related sequences in putative T-cell receptor genes. The amino acid compositions of the V TM were distinct from those of mammalian Ig, major histocompatibility complex (MHC) antigens, and viral glycoproteins, but significant similarities occur with Ig V regions or heavy chains of primitive vertebrates. The results indicate that the V H-bearing T-cell products are not classical Ig, but bear limited V H-cross-reactive determinants.

Clonal diversity and homology of latent and nominal group a immunoglobulin allotypes in the rabbit

Latent V H immunoglobulin allotypes are expressed unexpectedly and transiently at low concn in the serum of rabbits. Latent group a1 molecules in sera from rabbit colonies in Philadelphia (U.S.A.) and Birmingham (U.K.) were examined for a1 specificity and clonal diversity using reference nominal allotypic reagents and isoelectric focusing (IEF) autoradiography. Latent a1 molecules from rabbits of both colonies had diverse spectrotypic patterns in the pI range 5.5–8.3, as identified with 125I-labelled affinity-purified specificity-tested, anti-nominal a1 antibody. Comparisons of spectrotypes between nominal a1 antigen and latent a1 focused molecules revealed a marked correspondence in banding over the pI range. Reference anti-nominal a1 antibodies could be absorbed out substantially by the IgG fraction of serum from two rabbits containing latent a1 molecules; in a reciprocal fashion absorption with nominal a1 molecules reduced the binding of focused latent a1. The latent a1 molecules from both U.S.- and U.K.-bred rabbits displayed strikingly similar IEF spectra and their antigenic similarities were confirmed by similar absorption capacities of the reference anti-a1 serum. When sequential serum samples from one (U.S.) latent a1 rabbit were compared by IEF, some bands, e.g. those between pH 7.75 and 8.3, appeared to fluctuate in their presence, whereas others, e.g. between pH 5.3 and 7.4, were expressed continuously. We can conclude that latent a1 molecules are clonally complex and some are consistently produced in small amounts. As they also show antigenic similarity, if not identity with nominal a1, we believe that they are probably the product of the same gene (or genes) with an equivalent capacity to be associated with specificity-determining genes even though the level of synthetic activity is lower and possibly governed differently. Anti-a1 antibody was raised in a rabbit in which latent a1 allotype had been previously detected. This antibody was of low avidity and, while inhibitable on RIA by nominal a1 it was not inhibitable by the donor's latent a1 or by a second latent a1 of the same (partially inbred) U.K. colony, but was inhibitable by a latent a1serum from the Philadelphia, U.S.A. colony. This result suggests that a1 molecules are the products of more than one gene.

Complement Fixation by Pemphigus Antibody. I. In Vitro Fixation to Organ and Tissue Culture Skin

Although complement is often detected in the intercellular substance of pemphigus skin lesions, the ability of pemphigus antibodies to fix complement in vitro is controversial. The purpose of this study was to test in vitro complement fixation abilities of pemphigus antibodies further using organ and tissue culture methods. Epidermal cell monolayers from mouse tail were incubated with the purified IgG fraction of pemphigus serum followed by purified Clq. Binding of Clq, as well as IgG was demonstrated by immunofluorescence methods. When purified Clq was replaced with normal human serum as a complement source, positive C3 and C4 staining were also evident. When purified IgG of normal human serum was used in place of pemphigus IgG, similar immunofluorescence staining was not observed. Further evidence for complement fixation in vitro by pemphigus antibodies was obtained using organ cultures. Organ culture of normal human skin and monkey esophageal mucosa cultured in purified pemphigus IgG showed intercellular substance binding of IgG. No binding was observed when normal IgG was substituted for pemphigus IgG. Additional organ culture sections were then treated with complement (fresh normal human serum) and tested by in vitro complement staining. Fixation of Clq, C4, and C3 was noted in intercellular substance areas of organ cultured skin and mucosa incubated with pemphigus IgG but not those incubated with normal IgG. Prior treatment of pemphigus IgG organ cultured skin sections with unlabeled anti-C3, blocked positive C3 staining. These results suggest that some pemphigus antibodies are capable of activating complement in vitro.

Humoral and cellular immune reactions against tumor cells in patients with urinary bladder carcinoma. Correlation between direct and antibody-dependent cell-mediated cytotoxicity.

Serum IgG fractions from a large and homogeneous group of patients with transitional cell carcinoma of the urinary bladder (TCC) were tested for their capacity to induce antibody-dependent cellular cytotoxicity (ADCC) with lymphocytes from healthy donors against a TCC-derived target cell and one derived from adenocarcinoma of the colon. Both targets have previously been shown to be of comparable susceptibility to cell-mediated lysis in vitro. Some of the IgG preparations showed strong and dose-dependent ADCC against either one or both targets, while others gave weak reactions or none at all. Similar results were obtained with IgG from a matched group of patients with prostatic carcinoma who were used as clinical controls (CC). In parallel experiments, lymphocytes taken from the two donor groups at the same time as the serum samples were tested for their direct cytotoxicity (CMC) against the two targets. CMC gave similar results to ADCC. The differences in cytotoxicity displayed by either IgG or lymphocytes from individual donors were analysed statistically, using nonparametric statistics. To avoid introducing bias due to arbitrary data selection, the entire set of results, comprising both high and low reactors, was included in the statistical assessment. ADCC of the TCC donors' IgG against the TCC target was significantly stronger than against the colon carcinoma and also significantly stronger than that of the control donors. Similarly, the TCC patients' lymphocytes displayed a significantly higher CMC against the TCC target than against the control targets. This was not seen when the lymphocytes from the patients with prostatic carcinoma were tested. When CMC and ADCC of individual donors were compared, a statistically significant correlation between these activities was seen in three of the four donor/target combinations. These results support earlier findings and suggest that a significant fraction of both the disease-related and the 'non-selective' CMC (NK) displayed by cancer patients lymphocytes against allogeneic tumor cells in vitro reflects antibody-dependent reactions.

Phagocytosis of Plasmodium falciparum-Parasitized Erythrocytes by Human Polymorphonuclear Leukocytes

Polymorphonuclear leukocytes (PMN) from normal blood donors phagocytosed P. falciparum-infected red blood cells (IRBC) to a greater extent than normal RBC under in vitro culture condition. The phagocytic activity of PMN was greatly increased by the addition of sera from individuals living in areas endemic for malaria (immune sera) but not by sera from individuals recovering from a first acute P. falciparum infection. The enhancement of the phagocytic activity was associated with the purified IgG fraction of immune sera and was lost after absorption of IgG on protein A sepharose column of preincubation of the immune sera with IRBC. These experiments suggest that opsonisation of IRBC and their subsequent phagocytosis may be one of the mechanisms involved in the clearance of P. falciparum infection in individuals living in areas endemic for malaria.

Two cases who showed C3 or C4 nephritic factor activity

C3 nephritic factor (C3NeF) was found in patients with membranoproliferative glomerulone phritis (MPGN) and in some cases of partial lipodystrophy. C3NeF was supposed to be the auto-antibody to C3 convertase (C3bBb) of the alternative complement pathway and stabilize it, resulting in characteristic complement profile in their serum.Recently C4 nephritic factor (C4NeF), which was thought to be the auto-antibody to C3 convertase of the classical complement pathway (C4b2a), was found in patients with systemic lupus erythematosus (SLE) or poststreptcoccal glomerulonephritis.We found C4NeF activity both in serum and urinary IgG fraction of a patient with SLE, who presented nephrotic syndrome and MPGN at the time of renal biopsy. The C4NeF activity in serum and urine disappered after the treatment of steroid therapy.We also found C3NeF activity only in serum IgG fraction, not in urinary IgG fraction, of a patient with ulcerative colitis, sclerosing cholangitis and chronic glomerulonephritis, of which biopsy specimen showed MPGN. However, the activity was atypical in comparison with C3NeF reported so far, because of its unstability and weakness in activating complement of normal human serum and it suggested heterogeniety of C3NeF.While C4NeF activity was detected both in serum and in urine, C3NeF was found only in serum. Thinking into consideration that selectivity of the urinary protein from the two patients did not differ, we speculated C3NeF had high affinity to the glomerulus.

Lymphocyte function in experimental African trypanosomiasis. V. Role of antibody and the mononuclear phagocyte system in variant-specific immunity.

The role of parasite-specific antibody and the mononuclear phagocyte system (MPS) in immunity to the African trypanosomes was examined. For this study C57BL/10SnJ mice were infected with Trypanosoma rhodesiense clone LouTat 1.0. Infected mice were injected with 75Se-labeled LouTat 1.0 trypanosomes, and clearance from the blood upon reexposure was measured throughout the course of infection. Clearance of labeled organisms occurred only on or after day 5, which was the day of natural elimination of LouTat 1.0 from the blood. Clearance was dependent on a functional immune system and correlated with the appearance of antibody to the variant-specific surface antigen (VSSA) of the trypanosomes. The ability to clear trypanosomes was transferred to normal, uninfected mice by immune serum. Both the IgM and IgG fractions of immune serum mediated the clearance, and VSSA-specific IgM fractions were as efficient in clearing LouTat 1.0 as the IgG fractions. Normal levels of complement (C3) were not required for clearance. The liver was the primary organ of clearance, and the ability of the liver to sequester radiolabeled trypanosomes was not impaired in the terminal phase of the disease or by large numbers of circulating trypanosomes present representing different variant antigenic types (VAT). We conclude that in African trypanosomiasis the MPS is not depressed in its ability to clear trypanosomes of the infecting VAT at any time during the course of infection. The observed clearance function requires parasite-specific antibody but normal levels of C3.

Trypanostatic Activity of Rat IgG Purified from the Surface Coat of Trypanosoma lewisi

Host IgG is a component of the surface coat of Trypanosoma lewisi; it is specifically acquired during infection in the rat, concomitant with a rise in titer of trypanostatic (ablastic) activity of host serum. Host IgG was eluted from trypomastigotes at 7 to 9 days postinfection with a high salt-low pH buffer. Surface coats and trypanosome ultrastructure were not notably altered by the elution procedure, as determined by electron microscopy. Rat IgG was removed and purified from the trypanosome eluates on an immunoadsorbent column made with the IgG fraction of anti-rat IgG serum coupled to Sepharose beads. Concentrated column eluates, by comparison with a standard, were shown to be rat IgG by immunoelectrophoresis and SDS polyacrylamide gel electrophoresis. As a control, IgG from normal rat serum was purified by the same technique. IgG-negative trypanosomes harvested from immunosuppressed rats bound IgG purified from surface coats of trypanosomes, but not IgG purified from normal rat serum, as demonstrated by subsequent labelling with FITC-conjugated, rabbit anti-rat IgG. The IgG purified from surface coats inhibited the reproduction of T. lewisi in an in vitro assay, but purified, normal IgG did not. These data show that antigen-specific host IgG, adsorbed to the surface of T. lewisi, is ablastic antibody.

Naturally-occurring antibodies which bind hyaluronate

Sera from a number of different species were found to contain a hyaluronate binding activity. This binding activity was detected by mixing the serum with [ 3 H] hyaluronate and then precipitating the proteins and any bound [ 3 H] hyaluronate by the addition of an equal volume of saturated (NH 4 ) 2 SO 4 . The binding activity associated with horse serum was examined further and found to be saturable, of relatively high affinity and specific for hyaluronate. Competition experiments showed that the binding was not influenced by the molecular weight of the hyaluronate, suggesting that the binding protein interacts with an intrachain region of the hyaluronate rather than the terminals. The binding activity co-purified with the IgG and IgM fractions of serum after (NH 4 ) 2 SO 4 precipitation, ion-exchange and molecular-sieve chromatography as well as after affinity chromatography.

Free thiol groups and labile disulfide bonds in the IgG fraction of human serum

The IgG fraction was isolated from freshly taken blood serum of healthy persons (male and female) by column chromatography on QAE-Sephadex. After 30 min incubation with DTNB (5,5′-dithio-(2,2′-dinitro)-benzoate) the average photometrically determined quantity of thio-anions was 0.24 ± 0.02 SH/mole IgG. Since this result remained unchanged even after 24 h incubation with DTNB, interaction with masked thiol groups cannot be assumed. If, however, the serum was incubated with DTNB for 24 h and the IgG fraction then isolated and treated with thioglycolate, an average of 1.51 ± 0.39 moles of thio-anions were liberated per mole of IgG. This indicates that on 24 h interaction with IgG, DTNB not only reacts with free SH groups, but also opens S-S bonds by a disulfide exchange reaction. The amount of thio-anions resulting from such opened disulfide bonds was calculated as the difference between 1.51 and 0.24, i.e., 0.64 S-S/mole IgG. This would be accounted for if approximately 64% of the IgG fraction is composed of a subfraction containing 1 labile disulfide bond per mole. The average of 1.51 thio-anions per mole IgG resulted from 130 single values with an essentially normal statistical distribution and standard deviation well within the usual biological range.

Human serum binding protein for vitamin D and its metabolites (DBP): Evidence that actin is the DBP binding component in human skeletal muscle

The tissue protein which tightly binds the human serum binding protein for vitamin D and its metabolites (HDBP) was studied in soluble extracts of human skeletal muscle. A tissue protein-HDBP complex was effected in vitro by the addition of human serum Cohn IV to high-speed supernatant from muscle, and the complex was partially purified by ion-exchange chromatography, gel filtration, and affinity chromatography. The faster-sedimenting complex was retained longer than HDBP on DEAE-Sephacel columns, and was estimated to have a size of 100,000 daltons by gel filtration. The complex displayed inhibitory activity to deoxyribonuclease I (DNase I), whereas HDBP alone did not. When the complex was applied to affinity chromatography columns, immunoassayable HDBP was retained by DNase I-agarose and two dominant proteins of ~58,000 and 45,000 M r were retained by the IgG fraction of anti-HDBP serum covalently bonded to amino-agarose, as revealed by sodium dodecyl sulfate-polyacrylamide electrophoresis. Pure HDBP does not bind to nor inhibit DNase I, but an actin-HDBP complex does. These data suggested that the tissue component with high affinity for HDBP was actin. Incubation of equimolar amounts of polymerized actin and pure HDBP in its apo form resulted in the depolymerization of the actin. This depolymerizing activity was also observed with HDBP saturated with cholecalciferol, 25-hydroxycholecalciferol, 24 R, 25-dihydroxycholecalciferol, or 1,25-dihydroxycholecalciferol.

Scanning electron microscopical observations on antigen-antibody coat formation on mechanically transformed Schistosoma mansoni schistosomula.

As part of a study of the antigenic composition of the tegument of mechanically transformed Schistosoma mansoni schistosomula, the phenomenon of coat formation around such schistosomula when incubated in medium containing serum of S. mansoni infected mice was investigated with light and scanning electron microscopy. Coat formation was only observed on freshly transformed schistosomula, while schistosomula that had been incubated overnight at 37 degrees C in medium without serum from infected mice were no longer able to produce a coat. When freshly transformed schistosomula were incubated in medium containing serum from infected mice, it was found that individual spines on the tegument were covered with a coat within 1 h. After 2 h of incubation, the schistosomula were completely covered with a thick coat, starting at the posterior end. This coat was actively shed by the schistosomula after 3 h of incubation. To investigate the mechanism of coat formation, experiments were carried out using serum from uninfected mice, heat-inactivated serum from infected mice, and the IgG fraction of serum from infected mice. From the experiments it was concluded that the coat consisted of antigen-antibody complexes, involving IgG antibodies and complement. A detailed analysis of the easily obtainable coats may lead to a better understanding of the antigenic structure of the cercarial and schistosomular tegumental membrane.

Growth of 17D yellow fever virus in a macrophage-like cell line, U937: role of Fc and viral receptors in antibody-mediated infection.

Abstract Growth characteristics of 17D yellow fever virus (17D-YF) and conditions for infection were studied in U937, a macrophage-like, Fc receptor-bearing continuous human cell line. Antibody to 17D-YF was obtained by immunization of normal subjects with 17D-YF vaccine. Cells were infected in the presence or absence of immune whole sera or immunoglobulin fractions. Infection of U937 was temperature dependent; the yield of virus was variable but at low temperature viral titers were consistently higher when infection was established in the presence of antibody. Results of infectious center assays indicated that the increased yield of virus was largely or entirely due to an increase in the number of cells producing virus early in the course of infection. Enhancement of viral growth was mediated by IgG but not IgM fractions of immune sera. Trypsinization of U937 resulted in a 90 to 95% reduction of infection in the absence of antibody but in the presence of antibody viral titers were higher in trypsinized than in nontrypsinized cells. Antibody to 17D-YF, contained in the whole IgG fraction of sera, bound to U937 to mediate infection without first being complexed to virus. Preincubation of U937 with IgG1 but not IgG2 myeloma proteins abrogated antibody-mediated infection. This result is compatible with the known affinities of U937 Fc receptors for specific subclasses of IgG and provides evidence for the role of the Fc receptor in antibody-mediated enhancement of viral growth. Persistent infection characterized by a lack of detectable cytopathogenic effect was established in long-term cultures of U937. This pattern of infection might be related to the unique effectiveness of the 17D-YF vaccine.

Immunoaffinity chromatography of proteins. A gentle and simple desorption procedure

A gentle procedure for desorption in immunoaffinity chromatography was investigated. Barley β-amylase absorbed on the Sepharose-immobilized IgG fraction of the anti-barley β-amylase immune serum was used in this study. Elution with water did not desorb the antigen by using a continuous elution procedure. However, desorption with water became effective when the elution procedure involved an interruption of a few hours. Several factors of the desorption in these conditions were further investigated. At best, up to 35% of the absorbed antigen could be desorbed in one fraction. Preliminary assays carried out with another plant protein and its corresponding antibodies provided similar results.