Distribution of 3H-labeled staphylococcal alpha-toxin and a toxin fragment in mice

Staphylococcal alpha-toxin and a toxin fragment were labeled with N-succinimidyl[2,3-3H]propionate. The labeled compounds retained greater than 95% biological activity. The distribution of labeled staphylococcal alpha-toxin and alpha-toxin fragment after intravenous administration to BALB/c mice was studied with whole-body and microautoradiography. The animals were divided into three groups that received (i) labeled alpha-toxin only, labeled alpha-toxin after prior injection of unlabeled fragment, or labeled fragment only. After 5 min, the distribution patterns were similar in groups 1 and 2, with the highest amounts of radioactivity found in the blood vessels, liver, spleen, lungs, and kidneys, whereas the labeled fragment alone showed no initial accumulation in the lungs. The kidneys continued to show a high concentration of radioactivity, whereas the levels at 60 min had decreased in the other organs. The toxin showed continued stable binding to the proximal tubuli, whereas the toxin fragment seemed to dissociate and was found only in small amounts in the glomeruli. No radioactivity was found in the central nervous system.