Features of the reaction induced by 4 hours of TNF-α followed by RB6-8C5.

(A-B) Leukocytes adhere and form aggregates in venules (A) and arterioles (B). (C-D) Aggregates are comprised of neutrophils (marked N in panels C and D), platelets (marked P in panel D), and monocytes (marked M in panel D). (E) Plasma clots develop in obstructed vessels; pale pink areas suggest platelets and fibrin. (F) Intravascular fibrin deposition. Black electron dense fibrin strands are clearly evident. Section runs through a compartment that also contains RBCs (not shown). (G-H) Injected fluorescent albumin remains vessel bound after TNF-α (G), but rapidly leaks into tissues if RB6-8C5 is applied (H). (I-J) Arteriolar vasoconstriction is detected soon after RB6-8C5. Panel K shows a lung section from a mouse stimulated with TNFα (50 ng, intrascrotal). Alveolar capillaries appear congested and contain inflammatory cells, but the large vessel to the right remains open. Panel L shows a lung section from a TNFα-stimulated mouse subsequently treated with RB6-8C5. The large vessel running diagonally across the image is extremely congested.