Alternations in human plasma factor XIII levels and their relation to various biochemical constituents of blood

Abstract

In this study the factors affecting on Factor XIII (FXIII) levels of human plasma were investigated in 185 patients (98 male, 87 female) from 16 to 86 years of age, using single radial immunodiffusion method developed in our laboratory. Citrated plasma were sampled from antecubital vein by centrifugation at 3, 000r. p. m. for 10min. and stored at -20°C until use. Preparation for immunoplate was described in our preceding report. Results obtained were represented as percentage of Standard Human Plasma (from Behringwerke) employed for standard.Subjects, male and female, were divided respectively according to age into three groups; to 40 years old, from 40 to 59, over 60, and mean value (MV) in each group was estimated. MV of FXIII for subunit A (sub A) in younger male and female were 103.73 and 84.92, and for subunit S (sub S) were 97.93 and 92.33 respectively. In the other groups of male and female, MV for both subunits were almost in the same levels respectively.From observations analysed on the diurnal changes in sixteen patients with mild diabetes mellitus and on the seasonal alternations in ten patients with stable hypertension, no remarkable variabilities of both subunits levels were obtained. This finding indicates that sub A which is bound to sub S is kept stable under physiological conditions, and that it is hardly affected by exercise, meals and climate.On the other hand, following the changes of levels in seven CVA patients who were within seven days after accidents, it was observed that sub A decreased from early stage of the accidents, while the decrease of sub S appeared about ten days after onset. It seems that the decrease of sub A is caused by consumption which is brought about by coagulative events e. g. CVA, menstruation, and other hemorrhagic diseases, and by subsequent healing process after rapid activation of FXIII. In addition, the view is allowable that sub S is being retained in form of “free” for a time, thereafter disappearing gradually from plasma.The experiments to determine the relation between FXIII subunits and other biochemical plasma constituents were carried out. There were significant correlations between both subunits and total cholesterol (p<0.05).However, no significant correlation between both subunits and other lipids; triglyceride, β-lipoprotein, FFA and phospholipid, were obtained.Plasma fibrinogen had a correlation with sub S but not with sub A. As previously reported, a high correlation between sub A and sub S (r=0.440, p<0.05) was otained. Moreover, it has been generally accepted that about 30% of total sub S in plasma is present in form of free.From our findings and other reports, authors came to the concept that sub S may be present in forming complex with fibrinogen in plasma, and that it may bind with fibrinogen in preference to fibrin monomer.We suppose that sub S, especially “active free sub S” which releases sub A would be under labile condition, and that this “sub S” would react with fibrinogen, resulting in forming sub S-fibrinogen complex.