Thin layer gel filtration immunofixation: identification of abnormal molecular weight immunoglobulins or related fragments.

A simple procedure is described to identify immunoglobulin (Ig) fragments without isolation from biological fluids. It involves an initial separation based on molecular weight (MW) by thin layer gel filtration (TLG) followed by immunofixation (IF) in cellulose acetate strips with monovalent antisera. TLG-IF permits detection of differences about 10,000 Da MW and specific immunological typing, making it a useful tool in the accurate identification of protein fragments.

Immunofixation on cellulose acetate: an improved screening method for monoclonal immunoglobulins.

A rapid, simple and economical method is described for typing monoclonal immunoglobulins. It is a modification of the immunofixation electrophoresis method and cellulose acetate has been used as a supporing medium. It involves an initial electrophoretic separation followed by an antigen (Ag)-antibody (Ab) reaction 'in situ'. Eight samples can be typed on each 5.7 cm x 10.5 cm strip and only 20 microliter of commercial antiserum are required (about 2.5 microliter per sample). The method permits detection of monoclonal proteins at concentrations as low as 100 ng/microliter in only 60 min.

Two different Fc gamma receptor-dependent cytotoxic mechanisms triggered by monoclonal immunoglobulins.

It is known that the receptors for the Fc portion of IgG molecules (Fc gamma R) are widely distributed in cells of the immune system. The expression of Fc gamma R enables monocytes and neutrophils to destroy antibody-coated target cells through the antibody-dependent cell-mediated cytotoxicity (ADCC) mechanism. In addition, the interaction of immune complexes or aggregated IgG with monocytes or neutrophils led to the lysis of nonsensitized target cells in a process known as nonspecific cytotoxicity (NSC). Despite that ADCC and NSC are both triggered through Fc gamma R, the cytolytic mechanism involved in each reaction is different. In this paper we analyze the ability of human monoclonal IgG1, IgG2, IgG3 and IgG4 to induce ADCC and NSC. Our results demonstrate that each IgG subclass is able to induce both, NSC and ADCC, mediated by monocytes or neutrophils, indicating that there is no correlation between IgG subclass specificity and the ability to activate both mechanisms.

Immunocompetence and prognosis in children with acute lymphoblastic leukemia: combination of two different maintenance therapies.

Intensive chemotherapy in patients with leukemia produced immunosuppression. The level of immunocompetence correlates with prognosis. The immunological function of 29 children with acute lymphoblastic leukemia (ALL) in complete remission and on 2 different maintenance therapies was evaluated and compared with 16 normal children (Group A). Sixteen children (Group B) with ALL received 6 mercaptopurine (6MP) daily and methotrexate (MTX) twice a week, and 13 children (Group C) received 6MP and MTX weekly for maintenance. There was depression of both cellular immunity, measured by the number of T cells and skin tests, and humoral immunity, measured by number of B cells, primary antibody production to typhoid vaccine, and levels of immunoglobulins. However, continuous maintenance therapy (Group B) produced significantly more severe immunosuppression of cellular immunity than the intermittent therapy (Group C). Humoral immunity was equally depressed in both groups of leukemia patients, but was less altered than cellular immunity. Concomitantly, patients with intermittent maintenance chemotherapy had less hematologic depression, fewer episodes of infection, and fewer died in complete remission. Patients of both groups with higher levels of immunocompetence had better prognosis with longer duration of complete remission than patients with severe immunosuppression. Out of 6 patients with "favorable immunocompetence" only 1 relapsed at 7 months and the other 5 remain in complete remission from 8 to 31 months. Among 23 leukemic patients with "unfavorable immunocompetence," 15 relapsed and 8 remain in complete remission from 9 to 26 months.