Role of peripheral blood mononuclear cell (PBMC) phenotype changes in the pathogenesis of haemorrhagic fever with renal syndrome (HFRS).

Hantaviruses cause an important human illness, HFRS. Blood samples from 22 HFRS-positive, six seronegative patients and 15 healthy controls were examined in 1995, during the largest HFRS epidemic in Croatia. Results of double- and triple-colour immunofluorescence analysis showed an increased percentage of cytotoxic T cells (CD3+CD8+) in seropositive patients compared with seronegatives and healthy controls. The majority of seropositive HFRS patients expressed activation and memory antigens on T and B lymphocytes. The percentage of CD23+ and CD21+ B lymphocytes was lower in seropositive patients. HFRS patients had elevated levels of sCD23 and five had elevated total IgE. The increased expression of both early and late T cell activation antigens, e.g. CD25, CD71 and HLA-DR, memory cells and sCD23 positively correlated with biochemical parameters (AST, ALT, urea, alpha2-globulin) during the acute phase of HFRS. The phenotypic changes observed, especially early and late T cell activation markers, as well as memory cells, could be useful parameters in the evaluation of HFRS course, and prognostic factors of HFRS severity. Additional attention should be paid to liver involvement in the pathogenesis of HFRS.