Increase of lymphocytes expressing Fc-receptor class III (CD16) by exposure to human seminal plasma.

OBJECTIVE: To characterize conditions for the seminal plasma-induced increase of lymphocytes that express immunoglobulin G-Fc receptor class III (Fc gamma RIII). DESIGN: Peripheral blood lymphocytes were incubated in diluted seminal plasma or control media. Cells expressing Fc gamma RIII were quantified by using flow cytometry and fluorochrome-labeled monoclonal antibodies specific for Fc gamma RIII. The influence of incubation time, temperature, and seminal plasma concentration was investigated. Physical properties of the active seminal plasma substance were characterized by studying effects of dialysis and ultracentrifugation. The origin of the active seminal plasma substance was investigated by studying activity of autopsy materials from male accessory glands. Identity of cells that are influenced by seminal plasma activity was investigated by using two-color flow cytometry with monoclonal antibodies specific for Fc gamma RIII and different phenotypic markers of leukocytes. RESULTS: Incubation of lymphocytes in seminal plasma significantly increased percentages of cells expressing Fc gamma RIII. Maximal increases were observed after seminal plasma incubation at 37 degrees C for 90 to 120 minutes and increases were significantly correlated with seminal plasma concentration. Seminal plasma activity was not altered by ultracentrifugation (100,000 x g for 30 minutes) but completely removed by dialysis (12,000 to 14,000 pore size). Fc gamma RIII-positive lymphocytes markedly increased after incubation in prostatic but not in seminal vesicle secretions. Two-color flow cytometry showed that increases of Fc gamma RIII-expressing cells occurred within the subset of CD56-positive natural killer (NK) cells. CONCLUSIONS: Dialyzable compounds of prostatic origin induce significant increases of NK cells expressing Fc gamma RIII. These findings might reflect a novel regulatory mechanism acting on CD56-positive cells within the female reproductive tract after insemination.

Prevention of transfusion-associated graft-versus-host disease: selection of an adequate dose of gamma radiation.

To determine the optimal dose of gamma radiation necessary to inhibit T-lymphocyte function and prevent transfusion-acquired graft-versus-host disease (TA-GVHD), a donor plateletpheresis component was initially divided into ten 20-mL samples. One sample was not irradiated, while the other nine samples were treated with gamma radiation at doses ranging from 500 to 4500 cGy. T-lymphocyte function was subsequently measured by mixed lymphocyte cultures and mitogen stimulation assays. The results were assessed in each test by calculating the percentage of inhibition of each irradiated sample as compared to that of the unirradiated sample. The accuracy of the delivered dose of gamma radiation was measured with thermoluminescent dosimeters. It was concluded that a nominal dose of 3000 cGy (actual dose delivered, 2898 cGy) is the appropriate amount of gamma radiation needed to eliminate T-lymphocyte-mediated graft-versus-host disease.

Conversion of IgG-mediated complement-dependent cytotoxicity by reducing reagents.

Reducing reagents used in complement-dependent crossmatches reduce IgM but not IgG. A positive IgM crossmatch is not an absolute contraindication to allografting. We have studied an alloantiserum from a patient with 100% panel reactive antibody awaiting heart transplantation whose serum was reduced. Absorption of this serum with the patient's erythrocytes or leukocytes had no effect on the third-party cytotoxicity. Absorption with third-party plasma or serum was without effect. Crossmatch of this serum with an HLA-A,B,C-identical nonrelated target was positive, whereas crossmatches with the patient's HLA-identical siblings were negative. Crossmatches with the patient's five children showed one strong, three intermediate, and one weak cytotoxic reactions. No antibody-dependent cellular cytotoxicity activity was observed. Fluorescence-activated cell sorter analyses showed no IgM but strong IgG1 antibody present before and after reduction of the serum. Our data indicate some IgG antibodies are reducible. The transplantation outcome in the presence of reducible IgG alloantibodies is not known, but it is possible these antibodies are associated with graft failures in patients observed to have positive standard crossmatches that become negative in the presence of reducing reagents.