Isolation and immunochemical characterization of immunoglobulin-binding factor from bovine peripheral blood lymphocytes.

The shedding of immunoglobulin-binding factor (IBF) has been studied in peripheral blood lymphocytes during 1 h incubation at 37 degrees C. IBF was detectable in the incubating medium on the basis of their ability to bind immunoglobulin G (IgG) specifically. IBF was affinity purified on Sepharose beads coated with bovine IgG, fluoresceinated and identified by their biological activities, i.e., for binding immunoglobulin-binding factor labeled with fluoresceinizothiocyanate (FITC-IBF) to erythrocytes coated with purified antibodies (EAIgG) by fluorometric binding assay. The effect of various pH, temperatures and proteolytic enzymes on the binding properties of FITC-IBF to EAIgG was also studied. We showed that IBF are sensitive to pronase E, higher temperature and pH.

[The effect of gamma-interferon and phorbol myristate acetate on the Fc gamma-receptor ligand-binding capacity and on the target-conjugating and antibody-dependent cytotoxic activity of blood lymphocytes]. / Vliianie gamma-interferona i forbolomeristicheskogo atsetata na sviazyvaiushchuiu sposobnost' Fc gamma-retseptora s ligandom, mishen'kon''iugiruiushchuiu i antitelozavisimuiu tsitotoksicheskuiu aktivnost' limfotsitov krovi.

We investigated the ability of gamma-interferon (IFN-gamma) and phorbol 12-myristate 13-acetate (PMA) to influence the ligand-binding of Fc-receptors for immunoglobulin G (Fc gamma R) (conjugation of IgG to fluorescein izothiocyanate--FITC) of bovine blood lymphocytes and the antibody-dependent cell-mediated cytotoxic activity (ADCC). The results demonstrate that the IFN-gamma or PMA induced augmentation of ligand-binding capacity of Fc gamma R of bovine lymphocytes, and correlated well with the enhanced capacity to lyse L cells coated with anti-L cell antibody. The number of conjugates effector--target, formed by bovine lymphocytes in the reaction of ADCC, correlates well with ligand-binding capacity of Fc gamma R. It can be suggested that IFN-gamma or PMA may control the ADCC caused by Fc gamma R regulating its expression.

Quantitative binding of Fc-receptors, and antibody-dependent cell-mediated cytotoxicity of blood lymphocytes in healthy and chronic lymphocytic leukemic cattle.

The binding capacity of Fc-receptors for IgG of blood lymphocytes was studied in healthy cattle and cattle with chronic lymphocytic leukemia before and after incubation at 37 degrees C in basal Eagle's medium without serum. It was found that lymphocytes of leukemic cattle possess twice the amount of Fc-receptors found in normal lymphocytes. The changes in the binding capacity of Fc-receptors for IgG of normal and leukemic lymphocytes correlated with those of antibody-dependent cell-mediated cytotoxicity (ADCC) of the corresponding lymphocytes. The lower ADCC of leukemic lymphocytes in comparison with normal ones was accompanied by a lower association constant of the leukemic lymphocyte Fc-receptors towards IgG.

Differences in the cytologic characteristics of antibody-dependent cellular cytotoxicity of normal and leukemic bovine blood lymphocytes.

Peripheral blood lymphocytes from cows with chronic lymphocytic leukemia (CLL) and normal control animals were examined in vitro for antibody-dependent (AD) cellular cytotoxicity. Lymphocytes from bovine CLL showed high levels of killer (K) cell activity against antibody-coated, 3H-thymidine-labeled xenogeneic L target cells, as measured by residual radioactivity. Morphologic studies of AD lymphoid cytotoxic reaction recognized in vitro by effector-target binding revealed striking differences between leukemic and healthy cattle. The total number of target-bound AD lymphocytes was increased in all CLL animals. The data obtained show that the subpopulation of Fc receptor-bearing blood lymphocytes in CLL is significantly greater than that of healthy animals. The phenomenon of multiple, multilymphocytic, effector-target cellular complexes formed during AD leukemic lymphoid cytotoxic reaction is suggested as an additional in vitro parameter in the diagnosis of CLL.