M. van der Giessen

Quantitative measurement of cytomegalovirus-specific IgG and IgM antibodies in relation to cytomegalovirus antigenaemia and disease activity in kidney recipients with an active cytomegalovirus infection.

In a longitudinal investigation 103 kidney recipients were studied with respect to the development of cytomegalovirus (CMV) specific antibodies of the IgG and IgM class, in relation to the detection of CMV antigenaemia (immediate early antigen. IEA), in weekly obtained blood samples during the first 3 months after transplantation. In 15 out of 49 (31%) seronegative patients a primary infection occurred, which was characterized by a quick rise in IgM antibody followed by a slower production of IgG antibody, high maximum numbers of IEA+ cells, and a CMV syndrome in 11 patients, ln 35 out of 54 (65%) seropositive patients a secondary infection occurred. After a post‐operative fall in the IgG antibody, which was also found in patients without an active infection and which was accompanied by a similar drop in scrum albumin and IgG, a second dip in IgG antibody was found 6 days before the first IEA+ leucocyte appeared in the blood. This was followed by a significant increase, indicative of an active immune response in consequence of the infection. 18 days later. In 31 of these 35 patients an IgM response was found. This could be ascribed to the presence of rheumatoid factor activity in 20 of them. Eight patients who showed a transient rise in IgG antibody between the two dips could be distinguished from the remaining ones by a lower maximum number of IEA+ cells and less severe disease symptoms. The described results suggest that (i) an adequate humoral immune system may prevent symptomatic CMV disease in secondary infections; and (ii) CMV‐specific antibodies may be removed from the circulation by antigens present in infected tissues before CMV antigenaemia becomes detectable.

Cytomegalovirus‐specific antibodies to an immediate early antigen and a late membrane antigen and their possible role in controlling secondary cytomegalovirus infection

In 24 renal transplant recipients who had a secondary cytomegalovirus (CMV) infection, the magnitude and development of CMV‐specific antibodies directed against two different antigens were studied in relation to the presence of CMV‐immediate early antigen‐positive peripheral blood leucocytes (CMV antigenaemia). These antibodies were measured in an antigen‐capture ELISA using two monoclonal antibodies: one directed against the major immediate early antigen (IEA) and a second one directed against the CMV‐encoded glycoprotein B (gB). A statistically significant inverse relationship between the level of anti‐IEA antibodies present at the time of transplantation as well as the magnitude of the increase of these antibodies during CMV infection and the maximum number of IEA‐positive cells during infection was shown. In contrast, both anti‐gB and anti‐total CMV antibodies did not give any correlation with the CMV antigenaemia. This may indicate that the anti‐IEA immune response plays a role in defence mechanisms against a CMV infection.

FC-GAMMA-RECEPTORS ON LYMPHOCYTES FROM NORMAL DONORS AND PATIENTS WITH LYMPHOPROLIFERATIVE DISEASES - INFLUENCE OF INCUBATION CONDITIONS

The antibody-coated human erythrocyte and the antibody-coated ox erythrocyte rosette assays (EAHu and EAOx) were compared to detect Fc gamma receptors on human peripheral blood lymphocytes. Two incubation conditions were examined: 1 h at room temperature and overnight at 4 degrees C. In healthy persons, in patients with Hodgkins disease and in patients with non-Hodgkin lymphoma (NHL) the mean percentage of EAHu-rosette-forming cells (EAHu-RFC) increased significantly when the incubation was carried out overnight at 4 degrees C instead of 1 h at room temperature. This increase was caused by Fc gamma receptor-bearing T cells. In the case of EAOx-RFC only a slight increase was found. The percentage of EAHu-RFC and EAOx-RFC differed significantly in the healthy group after the overnight incubation and in the NHL group after the 1-hour incubation. When comparing the mean percentage of EA-RFC in the patient groups with that of the healthy persons significant increases were observed: EAHu-RFC in patients with Hodgkins disease in the overnight incubation and EAOx-RFC in patients with Hodgkins disease and NHL in both incubation conditions. In patients with chronic lymphocytic leukemia (CLL, B-cell type) the mean percentage of EAHu-RFC was very low, however that of EAOx-RFC was moderate to high. It is concluded that in the two rosette assays the antigen-antibody complexes may have different avidities to different lymphocyte subpopulations, and that incubation conditions may have an influence on this avidity.

Abnormal reticuloendothelial function in patients with active vasculitis and idiopathic membranous glomerulopathy - a study with tc-99m-labeled heat-damaged autologous red-blood-cells

Reticuloendothelial function was assessed in 11 patients with systemic lupus erythematosus, 8 patients with Wegeners granulomatosus, and 20 patients with idiopathic membranous glomerulopathy by using autologous 99mTc-labeled heat-damaged red blood cells. With this method organ uptake could be measured by quantitative scintigraphy. There was no relation between the T1/2 of the blood disappearance curve and the T1/2 of the splenic uptake curve. The T1/2 of the blood disappearance curve was normal in all three patient groups. However, there was asignificant shift from spleen to liver uptake in patients with active systemic lupus erythermatosus, active Wegeners granulomatosus, and membranous glomerulopathy in comparison with a control group. There was no relation with age, level of circulating immune complexes, complement level, kidney function, or immunosuppressive treatment. We conclude that an increease of the liver component of reticulo-endotherlial function may compensate abnormalities in splenic function. This stresses the importance of quantitative scanning to detect such abnormalities. The study provides evidence for disease related hyposplenism in patients with active systemic lupus erythematosus, active Wegeners granulomatosus, and membranous glomerulopathy.