Differentiating feline T and B lymphocytes by rosette formation.

The number of bone marrow-derived and thymus-dependent lymphocytes in the peripheral blood of felines was assessed. Feline bone marrow-derived lymphocytes were determined by erythrocyte antibody complement (EAC)-rosette formation and membrane immunofluorescence. A good correlation was observed between the cells forming EAC-rosettes (mean of 40.2 +/- 9.7%) and those possessing membrane immunoglobulins (mean of 45.3 +/- 4.1%). Feline thymus-dependent lymphocytes form non-immune (E)-rosettes with rodent erythrocytes (mouse, rat, guinea pig) but not with erythrocytes from humans, monkeys, dogs, mongooses, chickens, rabbits, sheep, and hamsters. An average of 32.3 +/- 992% of the peripheral blood lymphobytes of cats formed rosettes with guinea pig erythrocytes. Antibody blocking, cytotoxicity, and mix-rosette studies demonstrated that guinea pig red blood cells bind specifically to T lymphocytes. Of feline peripheral blood lymphocytes, 41.0 +/- 7.5% showed fluorescent staining with fluorescein-labeled rabbit anti-cat thymus antiserum.