Seroprevalence of hantavirus antibodies in Germany as determined by a new recombinant enzyme immunoassay.

In order to elucidate the epidemiological importance of hemorrhagic fever with renal syndrome in Germany, the prevalence of antibodies against hantaviruses was determined in 13,358 sera from residents of various geographic regions, 1,284 sera from occupational risk groups and 287 sera from chronic hemodialysis patients. Serological investigations were performed using a highly specific transferable solid phase enzyme immunoassay based on the recombinant nucleocapsid proteins of a Hantaan and a Puumala serotype strain. The overall antibody prevalence was found to be 1.68%. In the serum panels from western and southern Germany, it was determined to be 1.83% on average in contrast to only 0.8% in the panel from eastern Germany. An endemic focus revealing an antibody prevalence of 3.12% was detected in a low-mountain area called Suebian Alb, which is located in the federal state of Baden-Württemberg. Occupational risk groups and a group of chronic hemodialysis patients showed a significantly elevated antibody prevalence ranging from 3.3% to 10%. The Puumala serotype was found to be the prevailing virus, but the percentage of sera predominantly recognizing the Hantaan nucleocapsid protein increased towards the south and the east and was significantly elevated in dialysis patients.

Monoclonal antibodies to leucosialin (CD43) induce homotypic aggregation of the human mast cell line HMC-1: characterization of leucosialin on HMC-1 cells.

CD43 (leucosialin, sialophorin) is the major sialoprotein of nearly all circulating leucocytes and has important biological activities in cellular differentiation and activation. Recently, the expression of CD43 has also been demonstrated on mast cells and basophils by flow cytometry. In order to further characterize mast cell/basophil leucosialin we have investigated CD43 on the human mast cell line HMC-1, the human basophilic precursor cell line KU-812, and the human promonocytic cell line U-937. The apparent molecular weights (MW) were 123,000 (HMC-1 and KU-812) and 144,000 (U-937) by Western blot analysis. Expression of CD43 on HMC-1 was down-regulated after stimulation with phorbol myristate acetate (PMA). Three monoclonal antibodies (mAb) specific for human CD43 induced homotypic mast cell line (HMC-1) aggregation in a semi-quantitative assay, a phenomenon that has not been described before with mast cells. Monoclonal antibodies specific for seven other surface antigens and an irrelevant mAb of the same isotype had no effect. The level of aggregation was dependent on anti-CD43 mAb concentration, time and temperature. Anti-leucosialin-induced aggregation of HMC-1 cells was completely inhibited by mAb against CD11a (LFA-1) and CD18 (beta 2-chain). Monoclonal antibody to CD54 (ICAM-1) partially inhibited anti-CD43-induced homotypic aggregation, while anti-CD11b (CR3), anti-CD11c (p 150, 95) and a control mAb had no inhibitory effect. We conclude that mast cell line CD43 antigen expression is differentially regulated during cell activation, and speculate that anti-CD43-induced homotypic aggregation of HMC-1 cells is closely associated with modulation of beta 2-integrins.