Differential immunogenicity of radiolabeled antibodies

227

Around the Nuclear World 2. 3.

KABALKA G. W. Syn. Commun. lo,93 (1980). KABALKA G. W. and GOOCH E. E. J. Org. Chem. 45, 3578 (1980).

This work was supported by the National Institutes of Health Department of Energy Contract No. DE-ASOS-80EV10363).

27. Differential Immunogenicity

(l-ROl-GM-25817-02)

and the U.S.

of Radiolabeled Antibodies

J. BRAY, A. NOUJAIM*, C. TURNER, B. C. LENTLE and T. A. MACPHERSON Cross Cancer Institute, ton, Alberta. Canada

Edmonton,

Alberta and *Faculty of Pharmacy,

University

of Alberta, Edmon-

Our interest in human anti-T as a useful tumor localizing agent has prompted us to label this antibody with radioiodine. The chloramine-T and ICl methods were used under a variety of conditions whereby the labeling of the antibody was undertaken prior to, and after the protection of active sites on specific immunoadsorbents. The biological integrity of the “*I labeled protein was tested under in vitro and in viuo conditions. Results indicate that the method of labeling as well as the technique of testing the antibody’s avidity for the intended antigen are extremely important. Whereas in vitro tests indicate essentially similar avidity and specificity for either the chloramine-T or ICllabeled antibody, this was not the case for the in L~L~O cellular test. Protection of the antibody’s active site by fixation on an immunoadsorbent, prior to radiolabeling, was also shown to be imperative for the maintenance of biological activity.

28. Effect of Production on Distribution of Fatty Acids D.

GERSON,D. LYSTER, C. CHUNG and J. VINCENT*

Faculty

of Pharmaceutical

*TRIUMF, Variations

University

Sciences,

in the production

distribution

University

of British Columbia, technique

of radiolabelled

in the body. We therefore

media, and sonication

on distribution

of British Columbia.

Vancouver,

investigated

Vancouver,

B.C., Canada

and

B.C., Canada fatty acids may result in deviations

the effect of the method

of iodododecanoic

acid and (1-C-14)

in their

of labelling,

suspending

dodecanoic

acid in the

mouse at 5 min post-injection. Two methods

of iodination

were studied involving the interhalogen

a terminal

bromine

atom. One procedure

requires

radioactive

iodine in acetone for four hours. The other method

MIK for 15 min at 120°C. The final technique hydrolysis

refluxing

(2) Tween-80,

D5W, PG(10:80:

involves autoclaving

involves the production

to a fatty acid by refluxing the mixture in NaOH

in (1) albumin,

exchange of radioactive

the omega-brominated

iodine for

fatty acid with the fatty acid in

of a nitrile and its subsequent

at 1oo’C. The fatty acids were suspended

lo), or (3) Tween-20,

D5W, PG(10:80:10)

and soni-

cated or left unsonicated. In every case it was found that sonication

of the labelled fatty acid improved

the distribution

pattern.

The percentage uptake in the heart did not improve significantly but the heart/liver and heart/lung ratios were greatly improved. The best labelling method was by autoclaving. The shorter reaction time reduced the effect of heat on the fatty acid and minimized the need for sonication. It would appear

that heating

the fatty acid results in the formation

of a colloid.

sonication minimize this effect. No significant difference in distribution arations in HSA and those containing Tween-80. The Tween-20 mixture

Shorter

heating

times and

was noted between prepresulted in increased lung

and liver uptake. Therefore, the Tween-80 preparation is preferred as the fatty acid is more readily dissolved and the preparation does not involve the introduction of a foreign blood component.