Cobra venom factor-induced activation of the complement system: developmental, experimental and clinical considerations

Trypsin enhances sympathetic neuron-dependent plasma extravasation in the rat knee joint

Perfusion of 6-hydroxydopamine through the rat knee joint causes an increase in plasma extravasation by activation of sympathetic neuron terminals. Similarly, the increase in plasma extravasation in the rat knee joint produced by the inflammatory mediator bradykinin is dependent on the sympathetic post-ganglion neuron. There is evidence that both 6-hydroxydopamine and bradykinin release a number of mediators, some of which appear to enhance plasma extravasation and some which inhibit it. We attempted to determine the nature of inhibitory factor(s) by co-infusing trypsin (which rapidly cleaves peptides) with 6-hydroxydopamine. We observed a marked enhancement of 6-hydroxydopamine-induced plasma extravasation by trypsin. This effect appeared to be specific to neurogenic plasma extravasation since trypsin alone had little effect on plasma extravasation and trypsin did not affect non-neurogenic plasma extravasation (that produced by platelet activating factor). Taken together, the data suggests that 6-hydroxydopamine not only releases mediators from the sympathetic neuron that produce plasma extravasation, but also an inhibitor(s) of plasma extravasation that is peptide in nature.

Mechanisms of immune lysis of red blood cells in vitro. I. Paroxysmal nocturnal hemoglobinuria cells

The effect of five different reactions which activate complement (antibody activation, reduction in ionic strength, acidification, cobra venom factor (CoF) activation, and inulin activation) upon normal and PNH cells was investigated, using normal serum and serum devoid of the fourth component of complement (C4) activity from patients with hereditary angioneurotic edema (HANE) as a source of complement. Both normal and HANE serum lysed paroxysmal nocturnal hemoglobinuria (PNH) cells when complement was activated by acidification, CoF and inulin, indicating that the terminal steps of complement were activated in the absence of C4, presumably by the alternate or properdin pathway. Normal but not HANE serum lysed cells coated with anti-I, indicating that complement was activated by the C1-dependent classic pathway. HANE serum partially supported lysis by serum at reduced ionic strength, indicating that the activation of terminal complement components had occurred through both of the pathways of activation. The amount of the third component of human complement (C3) which was bound to the membrane of lysed and unlysed cells by these procedures was determined by anti-C3 absorption and was found to differ for each method of complement activation. In general, more C3 was bound to lysed cells than to unlysed cells. For given conditions, more was bound to PNH cells than to normal cells. However, very much less bound C3 was required for lysis of the PNH cells than for lysis of normal cells. These two phenomena, especially the latter, account for the marked lysis of PNH cells when complement is activated. Normal cells treated with AET (aminoethylisothiouronium bromide) did not bind more C3 than untreated cells and the lysed cells had less bound C3 than lysed PNH cells.