Abstract
Although delayed hypersensitivity reactions are clearly cell-mediated immunological events (1), an increasingly large body of evidence indicates that they involve the participation of several humoral factors produced by immune lymphocytes upon interaction with a specific antigen (2). In addition to these factors, the participation of serum complement (C) has been both suggested, (3-5) and denied (6, 7).
Cochrane, et al. have isolated a low molecular weight protein component of cobra venom (CoF) which has potent anticomplement activity (6). Since administration of this material in vivo causes a profound depression of C levels (6), purified CoF was used in the present study to analyze the role of C in delayed hypersensitivity in actively sensitized guinea pigs.
Materials and Methods. Random-bred female albino guinea pigs weighing 350-500 g were immunized with 0.1 ml of Freund's complete adjuvant (Difco, H37Ra) containing 2 × 10-8 M azobenzenearsonate-N-acetyltyrosine, distributed among the 4 footpads. Eighteen days later the animals were divided into control and experimental groups. On Day 20, they were shaved, depilated, and skin tested in 2 sites intradermally with 20 μg of azobenzenearsonate-1-glutamylalanyltyrosine (ABA-1-GAT) and 1:100 old tuberculin, (OT) each in 0.1 ml saline. Test sites were observed at 3 hr for evidence of Arthus reactions and measured at 24 hr for induration and erythema. Reactions were graded according to diameter of erythema in millimeters and intensity of induration as follows: — is no induration, + is slight induration, ++ is induration, +++ is central blanch, ++++ is central hemorrhage.
Cobra venom from the cobra Naja naja was obtained from the Ross Allen Reptile Institute, Silver Springs, FL. CoF was isolated by DEAE-cellulose and gel filtration chromatography as described by Cochrane et al. (6). The low molecular weight factor was sterilized by filtration through a Millipore membrane and stored at 4°.
Get full access to this article
View all access options for this article.