Short pulses of antigen induce in vitro an antibody response to haptenic determinants

Biogerontology research in Israel

The article describes the special features of gerontology research that has been expanding for five decades in Israel, and outlines the research in the biology of aging, covering a wide spectrum of areas and topics. A variety of associations, institutes and centers that have been established over the years play an important role in furthering the research and academic training.

Immune reactivity during aging. I. T-helper dependent and independent antibody responses to different antigens, in vivo and in vitro

The immunological status during aging was assessed by measuring the antibody response of the long-lived (C3H/eb X C57Bl/6J)F1 mice to various antigens in vivo and in vitro. In vivo, a decrease in antibody production to DNP and NIP haptenic determinants coupled on to BGG, as well as the response to SRBC, was observed. The decline was more pronounced in the IgG as compared to IgM antibodies. The results were recorded when various parameters such as antigen dose and kinetics of the response, were considered. Reduction of the antibody response was also noted when PVP was employed as immunogen. Similar results were noted when the responses to SRBC and DNP--polylysine were induced and followed in spleen organ cultures. In all of these experimental systems, the peak response was observed in mice 6--12 months old. From then on a gradual decrease was manifested, mice 30--36 months old producing significantly low responses. The results demonstrate that decrease in antibody production is expressed in the isolated spleen tissue in the same manner as in the intact animal. Furthermore, they were interpreted as indicating that the lesion may be at the T helper and the B cell compartments.

Suppression of anti-hapten antibody response in vitro by hapten-carrier conjugates

Production of antibodies was stimulated or suppressed arbitrarily by antigen treatment in vitro of spleens cultured at various time intervals after in vivo immunization. Spleens of mice immunized to the 2,4-dinitrophenyl or (4-hydroxy-3-iodo-5-nitrophenyl)acetyl haptenic determinants produced antibodies in culture when no antigen was applied in vitro. When a conjugate of the hapten to the same carrier employed for priming was given in vitro, an initial reduction of the response was observed, the level of which was dependent on antigen dose. Subsequently, increased amounts of antibodies were measured. In contrast, in vitro exposure to the hapten conjugated to an unrelated carrier resulted in significant reduction of the response for the entire period of the test. This suppressive effect manifested with various carrier proteins (ovalbumin, bovin IgG, bovine and rabbit serum albumin and keyhole limpet hemocyanin), when when applied to cultures in doses which were potentially immunogenic.

Decidual extracts suppress antibody response in vitro

Extracts of decidual tissue produced in pseudopregnant rats were found to suppress in vitro antibody response to alpha-2,4-dinitrophenyl-polylysine. The peak levels of both the total antibody response and the 2-mercaptoethanol-resistant fraction were reduced. Extracts prepared in a similar manner from uteri of normal untreated or pseudopregnant rats did not exert such an effect.

Requirement for persistent extracellular antigen in cultures of antigen-binding B lymphocytes

A system was established to assess the requirement for continuous presence of antigen in B-lymphocyte activation to antibody formation. Mouse spleen B lymphocytes, enriched for cells bearing anti-NIP (hapten 4-hydroxy-3-iodo-5-nitrophenylacetic acid) receptors, were pretreated briefly with NIP-POL (polymerized flagellin) antigen, washed, and added in small numbers to microcultures. The behaviour of these cells was compared with that of cells cultured in the continuous presence of antigen. Unfractionated spleen cells were studied under similar conditions. In contrast to unfractionated cells, enriched cells could not be triggered effectively by brief contact with antigen at any concentration tested. Fewer cells were activated, and clone size was smaller after brief contact with antigen than when antigen was present continuously. Furthermore, brief contact at high concentration did not cause tolerance induction.