Myron A. Leon

Three IgA Myeloma Immunoglobulins from the BALB/c Mouse: Precipitation with Pneumococcal C Polysaccharide

Three of 64 IgA immunoglobuilins, derived from plasma cell tumors induced by mineral oil in BALB/c mice, precipitated with species-specific pneumococcus C polysaccharide. A related antigen was also found in group O and some group H streptococci. A difference in ability to precipitate a C polysaccharide from a pneumococcus type XIV was demonstrated between protein 603 which did precipitate and protein 167 which did not precipitate this polysaccharide. Studies of the 167 and 603 proteins showed differences in electrophoretic mobility and polypeptide chains. The antigen-combining site of the 167 and 603 proteins resided on the papain-digestion Fab fragment.

Concanavalin A Reaction with Human Normal Immunoglobulin G and Myeloma Immunoglobulin G

Concanavalin A precipitated less than 5 percent of immunoglobulin G from human serum. It reacted with all of 42 myeloma serums of the immunoglobulin G type tested, but no more than approximately 50 percent of the total myeloma protein was ever precipitated. The fact that not all of the protein was precipitated and that the amounts precipitated varied from serum to serum may be interpreted as demonstrating heterogeneity of the carbohydrate in these myeloma proteins. Other glycoproteins precipitated by concanavalin A were identified, and subsequently separated from concanavalin A by chromatography.

The affinity of concanavalin A and Lens culinaris hemagglutinin for glycopeptides

The affinity of concanavalin A for ovalbumin, transferrin and glycopeptides from these proteins and from IgM has been investigated by studying inhibition of a concanavalin A-dextran precipitation system. The mixture of glycopeptides from ovalbumin was a powerful inhibitor with an apparent association constant above 106. The parent glycoprotein was a poorer inhibitor, but capable of forming soluble complexes of sufficient stability for isolation by gel filtration. The other inhibitors were also of high avidity. In contrast, in another precipitation system, Lens culinaris hemagglutinin was inhibited by glycopeptides from transferrin and IgM (apparent association constant close to 105) but not by the ovalbumin glycopeptides.

Ihibition of Cytotoxicity of Lymphocytes by Concanavalin A in vitro

Human lymphocytes treated with the plant protein concanavalin A are stimulated to transform into blasts, without developing cytotoxicity for chicken erythrocytes. Prior treatment of lymphocytes with concanavalin A potentiated phytohemagglutinin-induced blast transformation and DNA synthesis but completely inhibited phytohemagglutinin-induced cytotoxicity. Inhibiton was not due to suppression of the mixed lymphocyte-erythrocyte aggregation normally caused by phytohemagglutinin. Inhibition of cytotoxicity was reversible when concanavalin A was removed from the lymphocytes by treatment with methyl-α-D-manno-pyranoside after 1 hour but not after 20 hours. The results indicate that blast transformation and cytotoxicity are separate expressions of lymphocyte stimulation.

Conglutination: Specific Inhibition by Carbohydrates

Conglutination of antigen-antibody-complement complexes is inhibited by a number of acetamido sugars, the most efficient being N-acetyl-D-glucosamine and closely related compounds. The effects of structural modification on activity of N-acetyl-D-glucosamine are described.

Studies on a phytohemagglutinin from the lentil: V. Binding of Lens culinaris hemagglutinin to lymphocytes and erythrocytes☆

Quantitative studies were performed on the binding of 125I-labelled Lens culinaris hemagglutinin A (LcH-A) to the surfaces of human erythrocytes, human lymphocytes, or rabbit erythrocytes. Human erythrocytes showed 5.8 × 105 surface receptor sites for LcH-A with an apparent association constant, Ka, of 5.9 × 106. Rabbit erythrocytes showed 4.1 × 106 receptor sites with a Ka of 1.7 × 106. Human lymphocytes showed 6.6 × 106 receptor sites with a Ka or 8.1 × 105. In each case the binding of LcH-A to these cells was shown to be reversible and LcH-A could be removed almost totally by washing the cell-LcH-A complex with mannosides. Under conditions used for lymphocyte stimulation, LcH-A was reversibly bound to surface receptors of human lymphocytes; and little, if any, LcH-A was either taken up by the cells or irreversibly bound to the cells during 4 days of culture. During this time extensive lymphocyte stimulation occurred, suggesting that transport of LcH-A into the cell was not a critical part of the stimulation process.

Studies on a phytohemagglutinin from the common lentil. VI. Stimulation of human peripheral lymphocytes in culture by Lens culinaris hemagglutinin A.

Abstract Human blood lymphocytes are stimulated in culture by the homogeneous lentil hemagglutinin LcH-A. 1 In order to stimulate lymphocytes LcH-A must be bound to the surface for 24 h after which blastogenesis occurs in the absence of LcH-A. Blastogenesis is prevented by either sugars which bind to LcH-A or specific rabbit anti-LcH. In the presence of LcH-A, there is an almost immediate increase in uptake by the lymphocytes of uridine and incorporation into TCA-precipitable material. At the same time there is a small increased uptake of leucine and incorporation into TCA-precipitable material. After a lag of 24 h, thymidine is rapidly taken up by the cells and also incorporated into TCA-precipitable material. Finally, a large increased uptake of leucine occurs during a period where the total cell number is increasing. A critical blastogenic committal time of about 24 h was observed which was characterized by thymidine uptake, and a change in cell surface properties. It is suggested that, because a similar sequence of events occurs with PHA (a phytohemagglutinin with a different specificity than LcH-A) and Con A, the three lymphocyte stimulants bind similar or identical receptor sites, and/or stimulate by a similar mechanism.

Complement: Inactivation of Second Component by p-Hydroxymercuribenzoate

p-Hydroxymercuribenzoate inactivates the second component of complement whether it is in solution or is fixed to a sensitized erythrocyte together with the first and fourth components. Inactivation by the drug is blocked but not reversed by cysteine. Partial purification of the second component of complement is described.

Role of Cations in Conglutination and in Formation of Properdin Zymposan Complex from Bovine Serum

Summary The conglutination of sensitized sheep erythrocytes or zymosan requires Ca++. Mg++ and Ba++ are inactive but Sr++ appears to substitute to a limited extent for Ca++. Zymosan inhibits conglutination of sensitized sheep cells by bovine serum. Bovine properdin and zymosan react readily in the absence of Ca++, but in the presence of Mg++, without any interference due to conglutination.

Kinetics of Human Complement

Summary The optimal temperature for lysis using human C‘ is from 30°-32°C. As the temperature decreases from 37°C to 22°C the kinetic curve approaches the sigmoid shape typical of guinea pig C‘.