Fusing antigens to cytotoxic T-lymphocyte antigen 4 (CTLA-4) represents an effective approach to enhance DNA vaccine efficacy. It has been speculated that the direct targeting of CTLA-4 fusion antigens to antigen-presenting cells (APCs) causes antigens to be processed and presented to T cells more efficiently, leading to a stronger immune response. In the present study, dendritic cells (DCs), the most potent APCs, were generated from human monocytes. The specific binding of CTLA-4 fusion protein to DCs was investigated by flow cytometry. The results showed that the CTLA-4 fusion protein was capable of binding to the B7 molecules on human DCs with specificity.

Circulating CD5+ B lymphocytes were studied in 39 Chinese patients with rheumatoid arthritis (RA). Blood cells were stained with anti-CD5 and anti-CD19 monoclonal antibodies and were analyzed by flow cytometry. The results showed that there was no elevation of CD5+ B cells in RA patients when compared with 41 healthy control subjects. The circulating levels of CD5+ B cell correlated neither with serum titers of rheumatoid factor (RF) nor with disease activities in these patients. The CD5+ B cell levels remained relatively constant after a serial follow-up for 12 months. The similar pattern of epitope density of CD5 antigens also existed in the same patients. Although most studies in Caucasians revealed increased levels of CD5+ B cells in RA patients, measurements of this marker were not useful for the evaluation of disease activities in Chinese patients. Levels of CD5+ B cells may reflect more individual genetic background and may play a minor role in the flare-up of activities in Chinese patients with RA.