The distribution of a rabbit thymic antigen and membrane immunoglobulins in lymphoid tissue, with special reference to mucosal lymphocytes.

We have examined rabbit lymphocytes from several tissue sources for membrane immunoglobulins with anti-antiserum for alpha, mu and iota heavy chains, as well as with an antiserum specific for a rabbit thymus lymphocyte antigen (RTLA). Among lymphocytes from bronchus-associated lymphoid tissue (BALT), Peyer's patches, thoracic duct and gut mucosa exclusive of Peyer's patches, alpha and mu predominated with roughly equal percentages of each being found. The distribution of cells with iota receptors was approximately half that of either of the two other classes. In splenic lymphocytes mu predominated, followed, respectively, in numbers by iota and alpha. Detection of RTLA on almost all thymus lymphocytes (94%), most thoracic duct lymphocytes (72%), and lower numbers of peripheral blood lymphocytes (44%), Peyer's patch lymphocytes (17%), and splenic lymphocytes (20%) indicated a similar distribution of this antigen between the lymphoid organs as has been found for the mouse thymus lymphocyte-specific antigens. Low numbers of RTLA-bearing lymphocytes were detected in both the BALT (18%) and the gut mucosa (11%). An unexpected finding was the number of "null" cells among the gut mucosa population, bearing neither thymic nor heavy chain markers. These results in toto support the view that lymphoid aggregates in lung and gut may both contain precursor populations of B cells destined for IgA production.