Enhancement of immune cellular agglutination by use of an avidin-biotin system.

Classically, one can increase the titer of an agglutinating or first antibody with an antiglobulin or second antibody. We have used an avidin-biotin system in place of antiglobulin to similarly extend the agglutination by an initial anticellular antibody. Erythrocytes were agglutinated by adding in succession, caproylamidobiotin-antibody, avidin, and extender (caproylamidobiotin-macromolecule). The macromolecules evaluated as extenders, in order of increasing potency, were fibrinogen, albumin, succinylated polylysine, and ribonuclease A. From comparative testing, we found that antiglobulin raised the titer of antibody from 2560 to 20,480, and the avidin-biotin tool raised the titer of caproylamidobiotin-antibody from 2560 to 10,240 without extender and to 81,820 with an extender of caproylamidobiotin-ribonuclease. Thus noncovalent extenders add to the capability of the avidin-biotin system to facilitate and substitute for an antibody.

Selenium-sulfur analogues. 1. Synthesis and biochemical evaluation of selenotetramisole.

(+/-)-2,3,5,6-Tetrahydro-6-phenylimidazo[2,1-b]selenazole (1-selenotetramisole) was prepared from 2-aminoselenazoline in a three-step synthetic sequence. Resolution with d-10-camphorsulfonic acid yielded the optical isomers which were compared with (+)- and (-)-tetramisole as inhibitors of alkaline phosphatase isoenzymes. At 8.7 X 10(-5) M the (-) isomer of both tetramisole and 1-selenotetramisole produced significant inhibition of bovine liver and placental isoenzymes but not of calf intestinal or human placental isoenzymes. The (+) isomers demonstrated no inhibition at these concentrations. The similarity in inhibitory activity of the (-) isomers indicates the virtual interchangeability of selenium for sulfur in the thiazolidine ring of the parent drug and the likelihood that 75Se-radiolabeled selenotetramisole can provide an in vivo tracer to tetramisole biodistribution.