Prompted by uncertainties over the possibility of ex-vivo alterations of fibrinogen
in plasma samples from patients receiving thrombolytic agents, we sought to 1) use
sodium dodecyl sulfate (SDS) and mild acidification to pH 5 as a general means for
inhibiting post-sampling proteolysis, and 2) assess the chemical state of fibrinogen
by immuno-electrophoretically profiling the molecular weight distribution of the fibrinogen-related
antigens in the sample. Blood samples taken into EDTA and PPACK were immediately centrifuged,
and plasma diluted 5X in 2% SDS and 0.04% monochloroacetic acid. Such samples showed
no changes in molecular weight distribution of fibrinogen-related antigens over 7
days storage at room temperature when analyzed by SDS-eleetro-phoresis on 3% glyoxyl
agarose foHowed by fixation with NaCNBHg3 and staining with fluorescent, affinity-purified anti-fibrinogen antibody. The method
of study was applied to 16 patients with occlusive peripheral arterial emboli, all
of which were successfully treated by catheter-directed administration of tissue plasminogen
activator (tPA). All patients presented abnormally high levels of degraded (predominantly
170-300 kD) and dimeric forms of fibrinogen both prior and subsequent to treatment,
and only 3 of the 16 patients underwent appreciable change in content or composition
of fibrinogen derivatives in course of treatment. Concentrations of dimers ranged
from 6 to 23 percent of the total fibrinogen. De novo elevations in degraded forms
of fibrinogen observed to accompany treatment of 3 patients were reflected in prolongation
of thrombin time while tests of sulfite precipitation underwent relatively minor change.
The more frequent absence of change in content of derivatives, particularly the dimeric
forms suggestive of a coagulopathic process, indicated that they were derived systemically
rather than from the occluding thrombus that was removed by treatment. The findings
raise a prospect that the clinically significant thrombosis in these patients may
be symptomatic of a much more generalized vascular coagulopathic process. The absence
of measurable change in molecular composition of fibrinogen-related antigens in course
of successful treatment of these patients attests to the efficacy of tPA as a thrombolytic
agent. Support: NIH Grants HL-19361 and HL-19767.
