ISSN:
1365-3083
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Contradictory reports regarding the ability of complement receptor type 2 (CR2,CD21) on normal B cells to activate complement (C′) via the alternative pathway (AP), prompted us to compare the performance of human peripheral blood B cells and the Epstein–Barr virus-positive Burkitt's lymphoma cell line, Raji (a well characterized AP activator) by using flow cytometry. Measured in terms of the membrane deposition of C3 fragments per cell, Raji cells were significantly (6- to 26-fold) more effective as complement activators than were normal B cells. Raji cells were also found to express approximately four to five times as many CR2 as normal B cells. In addition, they distinguished themselves by displaying a greater Ca2+-dependent activation, with pooled normal human sera (NHS) as the complement source, and by degrading unprotected C3b fragments from iC3b to C3dg/C3d at a significantly lower rate than the B cells. The Ca2+ dependency of Raji cell activation was found to be partially a result of classical pathway (CP) triggering by specific antibodies in the NHS, although other triggering mechanisms may also be involved. If the influence of these variations between Raji cells and normal B cells was excluded, by relating deposition of anti-C3d-reactive fragments, during AP activation, to the number of CR2 expressed, the difference in performance between the two cell types was found to be insignificant.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1046/j.1365-3083.1997.d01-122.x
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