Immunomodulating effects of synchronised plasmapheresis and intravenous bolus cyclophosphamide in systemic lupus erythematosus

Recent studies have suggested that synchronised plasmapheresis and intravenous pulse cyclophosphamide therapy reduce disease activity in SLE patients. The aim of the present study was to examine the immunomodulating effects of this therapy and compare it with changes seen with cyclophosphamide alone. Four patients with active SLE were studied. Two were treated with synchronised therapy and two received cyclophosphamide only for up to 26 weeks. Disease activity was measured by the SLE disease activity index (SLEDAI). Immunological studies were performed immediately prior to each treatment. Patients in both treatment groups improved as reflected by a fall in mean SLEDAI scores: synchronised therapy 33.5 to 11; cyclophosphamide only 13.5 to 4.5. Following synchronised therapy only there was a prompt and sustained increase in the mean percentage of CD8⁺ cells (20.8 to 54.8) which resulted in a fall in the CD4:CD8 ratio (1.95 to 0.62). With both treatment modalities there was a fall in the proportion of CD20⁺ cells (B lymphocytes) (synchronised therapy 10.5 to 3.2; cyclophosphamide only 5.6 to 2.2). However, only synchronised therapy resulted in a fall in the in vitro production of immunoglobulins which was unchanged or increased following cyclophosphamide alone. These results suggest that although both treatment modalities are efficacious in the treatment of active SLE they produce different immunomodulatory effects. Thus, both therapies reduce the number of circulating B lymphocytes whereas synchronised therapy also modifies cellular immunity by promoting the emergence of a phenotypic suppressor T lymphocyte population.