抄録
Streptokinase-streptodornase (SK-SD) is one of the extracellular products produced from streptococci, mainly from group A and C streptococci. SK-SD preparation has been frequently used for the assay of lymphocyte proliferation as one of the clinical tests for immunological response in man.
In this paper, it is shown that some factors suppressing the responses of murine and human lymphocyte proliferations to mitogen and specific antigen may be contained in the commercial SK-SD preparation.
The results obtained are as follows:
1) Murine splenic lymphocytes in spontaneous turnover were incorporated with the 8H-thymidine (8H-TdR) in vitro. However, the incorporation of 8H-TdR was suppressed by the addition of SK-SD preparation.
2) SK-SD preparation also suppressed the response of mitogen (Con A, PHA and LPS) and specific antigen induced-murine lymphocyte proliferation, and the suppression percentage was over 90% inn the presence of 10 μg/well of SK-SD preparation.
3) Murine splenic lymphocytes were treated with SK-SD preparation for 24h at 37°C in 5% CO2 prior to the addition of mitogens, and then the cells were washed with culture medium. Thereafter, mitogens were added to the cultured cells. In these cases, cell proliferation was not suppressed at all. On the other hand, the proliferations of cell treated with SK-SD preparation for 48h were remarkably suppressed.
4) SK-SD preparation dialyzed with dialysis tubing of mol. wt. 3, 500 daltons cut off, nondialyzable SK-SD fraction (non-D. SK-SD), could not suppress the murine mitogenic lymphocyte proliferation. These facts suggest that a suppressive factor to the lymphocyte proliferation contained in SK-SD preparation may be the substance of low molecular weight.
5) From the results of fractionation by gel filtration (employing Sephadex G-100 or Sephadex G-25) or high pressure liquid chromatography of the commercial SK-SD preparation, it was also clearly demonstrated that the suppressive fraction was low mol. wt. having no SK and SD activity.
6) The responses of human lymphocyte transformation to mitogen (Con A) or non-D. SK-SD per se were found to be significantly decreased by the addition of the substance of low molecular weight. These results suggest that non-D. SK-SD preparation should be used for assaying im-munological response when the commercial SK-SD preparation is utilized.
