Figure 7.

Immunohistochemistry for CD20, vervets, multiple organs. (A) Y. enterocolitica-positive vervet, mesenteric lymph node, case 6. CD20-positive B cells are present in follicles and the medullary sinus. (B) Control vervet, mesenteric lymph node. CD20-positive cells are most prevalent in the cortical follicles. (C,D) CD20-positive cells are rare in the placenta from a Y. enterocolitica-positive vervet (C, case 20) and in the control vervet (D). (E) Y. enterocolitica-positive vervet, colon, case 3. CD20-positive B cells are present in the colonic mucosa in areas of presumed gut-associated lymphoid tissue that are mostly effaced by necrosis and suppurative inflammation. (F) Control vervet, colon. CD20-positive B lymphocytes are abundant within gut-associated lymphoid tissue and rare in colonic mucosa. (G) Y. enterocolitica-positive vervet, lung, case 20. Few CD20-positive B cells lie adjacent to areas of necrosis. (H) Control vervet, lung. B cells are more prevalent and scattered throughout the alveolar walls of the control lung.