These activated B cells and plasmablasts
present antigen to CD4+ cytotoxic T cells at sites of disease.
Since we found that B cell differentiation to plasmablast is strongly inhibited by CR1, we supposed that the major B cell function, namely, Ig production, is also affected by the complement-derived ligand.
Caption: Figure 3: Impact of CR1 clustering on BCR-induced plasmablast formation (a-c) and IgM secretion (d-e) of human B cells.
In such cases, HHV8-positive plasmablasts
present in Castleman's disease have been shown to coalesce into microscopic aggregates and sheets (Figure 9).
When there is a predominance of plasmablasts
or immunoblastic cells, a slightly different approach may be of benefit: CD45, CD20, CD3, CD30, CD138, [kappa]/[lambda], EBV, HHV8, ALK, Ki-67, MYC, and BCL2.
As it was noted that in HIV-associated MCD, KSHV infects mu/lambdarestricted plasmablasts located in the mantle zone (and importantly, such cells express the CD20 surface antigen), separate reports regarding 12 patients treated with rituximab have appeared in the literature over the last 6 years.
Blood, in press) suggesting that relapse may not be due to progression of resistant MCD but due to ongoing lytic KSHV infection of plasmablasts.
These cells, called plasmablasts
or plasmablastic cells, are the KSHV/HHV8-infected B cells, which can be identified by immunostaining for the KSHV-associated protein, latent nuclear antigen-1 (LNA-1 or LANA).
Most primary gastrointestinal lymphomas, both in stomach and intestine and irrespective of their association with MALT, are large B-cell lymphomas, especially those composed of centroblasts, but may also include cases dominated by immunoblasts and, on occasion, plasmablasts
cells resembling plasmablasts to "microlymphoma" and frank plasmablastic lymphoma.
Large B-cell lymphoma arising in HHV8-associated MCD is defined as a monoclonal proliferation of HHV8-infected lymphoid cells resembling plasmablasts, expressing IgM, and arising in the setting of MCD.
HHV8 infected plasmablasts may also show variable expression of the viral interleukin 6 (v-IL6) and are CD20 [+ or -], [CD79a.