Figure 3.

Fc-AK183 maintained week-long activity in vivo. (A) After iv injection of a single dose of 5 mg/kg Fc-AK183 in BALB/c mice (day 0), the animals received a bolus injection of purified human IgA1 iv after 1, 3, 7, and 10 days (three mice for each time point). Blood was collected in a time series (from 0 to 7 hours) for detecting IgA1 levels by ELISA to assess remaining Fc-AK183 activity in circulation. Over a 10-day period, the in vivo activity of Fc-AK183 from the initial injection was expected to gradually decline. (B) Compared with the PBS group, mice receiving Fc-AK183 treatment had significantly faster decline of IgA1 levels at the 1.5-, 3-, 5-, and 7-hour time points. Although the rate of substrate (IgA1) clearance slowed down toward the end of the 10-day (10d) period, significant Fc-AK183 activities toward IgA1 clearance as compared with that by control PBS injection were observed across all IgA1 time points (*P<0.005 for remaining IgA1 percentage). (C) To directly compare the action time of Fc-AK183 versus untagged AK183 (also similarly produced from E. coli expression), we injected Fc-AK183, AK183, or PBS control to mice. One day after the injection, we administrated a separate dose of purified human IgA1 for measuring the in vivo activities of the biologics, as in (A). Untagged AK183 and PBS were indistinguishable from each other, indicating a complete loss of activity of untagged AK183 one day after its administration. In contrast, Fc-AK183 induced significantly quicker clearance of IgA1 from circulation as compared with its untagged counterpart. (D) Body weight of mice (n=5) receiving Fc-AK183 injection did not show a decline during post-treatment days.