Immunoglobulin-positive cells from the gland of harder and bone marrow of the chicken

Cells were collected from the gland of Harder (GH) and bone marrow (BM) of 14-, 21- and 32-week-old birds and were incubated with an ¹²⁵I-labeled rabbit anti-chicken Ig (IgG and IgM) serum. At 14 weeks of age the percentage of Ig⁺ small lymphocytes (SL) in the GH and BM was similar. However, by 21 weeks of age Ig⁺ SL in BM had increased to approximately 19% of total lymphocytes while the Ig⁺ SL in the GH represented less than 1.7% of the lymphocyte pool. A marked drop in the number of Ig⁺ SL in BM occurred by 32 weeks of age. These data suggest that either the BM may be dependent on the bursa for maintenance of its Ig⁺ SL or it is unable to produce in situ or maintain Ig⁺ SL with age. In the GH the predominant cell was the plasma cell (PC). Labeled PC (> 20 grains) exceeded 80% of the total PC pool in the GH. These data contrast with the apparent deficiency of Ig receptors on murine PC. The maintenance of a large number of PC in the GH without the presence of Ig⁺ SL illustrates the uniqueness of this gland.