Immune capacity of the chicken bursectomized at 60 hours of incubation: failure to produce immune, natural, and autoantibodies in spite of immunoglobulin production.

Chickens surgically bursectomized at 60 hr of incubation were immunized at the ages of 6, 7, 8, and 9 weeks with Escherichia coli lipopolysaccharide, levan, tetanus toxoid, and dinitrophenyl-bovine serum albumin. All antigens were given on each occasion. All embryonically bursectomized (BX) chickens had detectable concentrations of serum IgM, IgG, and IgA. On the whole, the IgG level was markedly decreased and the levels of IgM and IgA were normal. Concentrations of serum immunoglobulins did not change during immunization in the BX chickens. In spite of the production of serum immunoglobulins the BX chickens were unable to respond to the immunization by production of specific antibodies, whereas the control (CO) chickens produced good antibody response to each antigen used. The BX chickens also lacked both natural antibodies to phosphorylcholine, fecal bacteria, rabbit red blood cells (RRBC), and MHC antigens and autoantibodies to the liver, kidney, and thyroidea. Neither were any antibodies to the bursal structures observed. These results support the hypothesis that the bursal influence is not necessary for isotype switch, but is essential for the production of specific antibodies.