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. 2003 Aug;77(15):8322–8328. doi: 10.1128/JVI.77.15.8322-8328.2003

FIG. 2.

FIG. 2.

Half-lives of IgG and Fab in serum and respiratory tract (RT). (A) Fab (130 μg) or IgG (7.5 μg) was injected i.p. into 2- to 3-month-old SCID mice. At various intervals, mice were exsanguinated by heart puncture under ketamine-xylazine anesthesia. The concentration of Fab or IgG in serum was determined by ELISA against PR8 immunoadsorbent, using biotinylated anti-Cκ for Ab detection and purified MAb H36-4 for standardization. Each point shows the log10 of the Ab concentration (nanograms per milliliter) in serum of an individual mouse. Linear regression analysis indicated systemic half-lives of 120 h for IgG and 4.5 h for Fab. (B) IgG (6 μg) and Fab (5 μg) were administered in a volume of 30 μl by the i.n. route to anesthetized SCID mice. At various intervals, mice were anesthetized and exsanguinated by heart puncture. BAL was performed and residual Ab eluted from finely minced lung tissue. The Ab concentration was determined as indicated above by ELISA of BALF and lung eluate. The total amount (concentration × sample volume) of lung-associated Ab was determined and is plotted on a log10 basis against the interval (hours) between administration and recovery. Linear regression analysis indicated topical half-lives of 8 h for Fab and 22 h for IgG.