Modulation of Mouse Anti-Trinitrophenyl Plaque-Forming Cell Affinity by Adjuvants or Lectins

Abstract

The effects of several kinds of adjuvants or lectins, such as Corynebacterium parvum, dextran, poly AU, poly IC, dibutyryl cAMP, concanavalin A (Con A), phytohemagglutinin (PHA) and pokeweed mitogen (PWM) on anti-trinitrophenyl (TNP) direct plaque-forming cells (PFC) in the spleen of mice and the affinity of antibodies produced by these PFC were examined. The numbers of anti-TNP PFC in the spleens of mice which had been injected with C. parvum 7 days in advance were greater than those in controls after immunization with TNP-coupled heterologous erythrocytes, while the affinity of antibodies released by these PFC was not affected. On the contrary, simultaneous injection of dextran with TNP-erythrocytes did not increase the numbers of splenic anti-TNP PFC, but heightened the affinity of antibodies released by these PFC. Copolymers of nucleotides, poly AU and poly IC, were capable of enhancing splenic anti-TNP PFC responses, but showed almost no altering of PFC affinity. Dibutyryl cAMP did not have any effect on this system. Con A had potencies to both augment the number of anti-TNP PFC and heighten the PFC affinity, while PHA seemed to lack these potencies. Injection of PWM in the presence of antigen increased the number of anti-TNP PFC and heightened slightly the PFC affinity. These results indicate that the heightening of the affinity at the cellular level is regulated in ways different from the augmenting effects on the number of anti-TNP PFC by adjuvants or lectins. These results are discussed in the light of the mode of action of the substances used.The anti-hapten antibodies secreted by antibody-producing cells (B cells) after antigenic stimulation are heterogeneous with respect to their affinity for hapten, and the antibodies with higher affinity increase with time after the stimulation [17,26,29]. The affinity of the antibody reflects the properties of B cells rather than those of T helper cells [16], but the helper cells still seem to have some influence on the alteration of the affinity of anti-hapten antibodies [9,18,30,31]. Injection of complete Freund's adjuvant or bacterial lipopolysaccharide (LPS) concomitantly with antigen results in a heightening of the affinity of serum antibody [20]. LPS is known not only to be a powerful adjuvant [21] but also to have a potency as a polyclonal activator [22].Our previous studies [27] indicated that LPS in the presence of antigenic stimulation has some effect on hapten-specific B precursors in heightening the affinity or in selecting high affinity antibody-producing progeny cells, but the alteration of antibody affinity and the increase in number of antibody-producing cells induced by LPS are regulated by different mechanisms. There are many other adjuvants and mitogens such as Corynebacterium parvum, dextran, polynucleotides and lectins, which can stimulate T or B cells specifically and result in augmentation of immune responses. To examine whether these substances affect the affinity of antibodies secreted from antigenstimulated anti-hapten antibody-pr...