Ultrastructure of Immunologic Processes

The effect of primary and secondary immunization on the lymphoid tissues of the carp, Cyprinus carpio L

Mirror carp immunized with human gamma globulin (HGG) in Freund's complete adjuvant (FCA) show a proliferative response involving cells whose cytoplasm stains deep red with methyl green-pyronin (pyroninophilic cells). This response occurs particularly in the haemopoietic parenchyma of the pronephros and mesonephros. It peaks at week 3, with the formation of clusters of pyroninophilic cells in the pronephros. Immunization with Aeromonas salmonicida elicited a less intense pyroninophilic response but caused a larger increase in pigment-containing cells. After a secondary immunization with HGG in FCA, a distinct response was observed in the spleen: Pyroninophilic cells collected within the ellipsoid sheaths in large numbers and formed nodules. The reticulum of such nodules acquired spherical proportions and resembled the white pulp reticulum of the tetrapod spleen. The roles of such pyroninophilic cells and the possibility that aggregations of them may be functionally analogous to homoiotherm germinal centres are discussed.

Human lymphoblast cell lines: antibody-dependent cytotoxicity

Five cell lines were isolated after prolonged culture of human buffy coat leukocytes. The cells consisted for the most part of lymphoblasts morphologically similar to those produced by in vivo or in vitro stimulation of small lymphocytes by antigens or mitogens. One of the lines possessed virus-like particles of the Epstein-Barr type. All the established lines were capable of mediating antibody-dependent cytotoxicity (LADC) quantitatively at a level not significantly different from that mediated by freshly isolated, normal human peripheral blood lymphocytes (PBL). The LADC of the lymphoblasts was inhibited by all the human IgG subclasses tested (IgG1, IgG2, IgG3, IgG4) as was the LADC of PBL. It is concluded that, at least so far, the lymphoblasts have retained the properties of the lymphocytes from which they were originally derived as regards their ability to mediate LADC.

Infectious mononucleosis: immunoglobulin synthesis by cell lines

Immunoglobulin synthesis by 16 long-term suspension cultures of mononuclear cells derived from peripheral blood of nine patients with heterophile-positive infectious mononucleosis (IM) has been demonstrated by radioimmunoelectrophoretic techniques. All cell lines synthesized molecules with IgG (gamma) heavy chain specificity. 14 cell lines produced molecules with IgM (mu) heavy chain specificity and 11 cell lines produced molecules with IgA (alpha) heavy chain specificity. No detectable synthesis of molecules with IgD (delta) heavy chain specificity was observed by these cell lines derived from peripheral blood of patients with IM. 13 cell lines produced molecules with type K (kappa) light chain specificity and 6 cell lines produced molecules with type L (lambda) light chain specificity. Of interest, 9 of 16 lines produced IgG (gamma), IgA (alpha), and IgM (mu) heavy chain molecules and 5 of these cell lines produced molecules with type K (kappa) and type L (lambda) light chain specificity as well. Further characterization by combined polyacrylamide gel filtration, immunodiffusion, and radioautography indicated the presence of newly synthesized immunoglobulin molecules with both heavy and light polypeptide chains in close association as well as free light polypeptide chain synthesis. Investigation of the localization of immunoglobulin in single cells by immunofluorescent techniques revealed that 5-22% of cells in these lines were strongly reactive with a fluorescein isothiocyanate-conjugated rabbit antisera directed against the antigenic determinants of human IgG and cross-reactive with the determinants common to IgA and IgM. No heterophile antibody, heteroagglutinin, or hemolytic antibody could be demonstrated in these cell lines derived from peripheral blood of patients with heterophile-positive infectious mononucleosis.

Ultrastructural localization of antibody in differentiating plasma cells

Antibody was localized by electron microscopy within differentiating and mature plasma cells of the spleens of hyperimmunized rabbits. Horseradish peroxidase was used as antigen. Intracellular antibody to peroxidase was revealed in glutaraldehyde-fixed tissue by coupling it with its antigen and then revealing the sites of peroxidase activity cytochemically. Antibody first appears in the perinuclear space of hemocytoblasts where it persists through differentiation into immature plasma cells, but it disappears from this site in mature plasma cells. Concomitant with the development of the ergastoplasm, antibody accumulates in many but not all of its cisternae. Antibody is present in the lamellar portion of the Golgi apparatus in all phases of plasmacytic differentiation. Mature plasma cells exhibit two types of antibody distribution, a concentration into large spherical intracisternal granules or an overflowing into all parts of the cytoplasm.