White Leghorn chickens were surgically bursectomized immediately after hatching and were matched with normal chickens with respect to weight (range: 150 to 400 g) and age (4 to 6 wk). Reticuloendothelial system (RES) function was determined after I.V. injection into a wing vein of 3H labeled gelatinized lipid test emulsion at a dose of 100 mg/100 g of body weight. Blood samples were collected by cardiac puncture every 2 min for a 14 min period. Samples were dried, weighed, counted and related to the injected dose. Data were transformed into logarithms and linear regression analysis was performed. Half time clearance (t 1/2) was calculated from the data thus obtained. Bursectomy markedly impaired clearance as the t 1/2 was delayed from 1.82± 1.23 min in controls to 6.26 ± 2.08 min in bursectomized birds. In order to determine if the observed impairment was due to a cellular defect or to a deficiency in a humoral phagocytic promoting factor or both, the system of recovery from RES blockade was used. To establish blockade in chickens, various doses (200 to 500 mg/100 g of body weight) of unlabeled emulsion were injected into a wing vein. Thirty min later, labeled emulsion (100 mg/100 g of body weight) was injected into a vein of the opposite wing. Blood samples were collected and assayed. By increasing the blockading dose, the t 1/2 was delayed from 2.83± 2.36 min after a 200 mg blockading dose to complete blockade at a 400 mg dose. Bursectomized chickens were completely blockaded at the 400 mg dose. Blockaded bursectomized and control birds were injected with labeled emulsion previously incubated (30 min at 37 C) with fresh sera from either bursectomized or control birds at a concentration of 2.5%. In another experiment, rat alpha 2 macroglobulin at the same concentration replaced the sera. Fresh sera from normal chickens reversed the blockade in control chickens (t 1/2=8.16± 2.01 min) and bursectomized chickens (t 1/2=8.69± 1.82 min). Rat alpha 2 macroglobulin also reversed the blockade in bursectomized birds (t 1/2=4.90± 2.66 min). Sera from bursectomized birds failed to reverse the blockade. It is concluded that the depressed clearance by the RES in bursectomized chickens appears to be due to a humoral serum factor deficiency rather than cellular inpairment.
|Original language||English (US)|
|Number of pages||7|
|Journal||RES Journal of the Reticuloendothelial Society|
|State||Published - Dec 1 1976|
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