Concepedia

Abstract

SUMMARY It is not known whether the exceptionally high frequency of T lymphocytes which respond to “strong” ulloantigens (Ag-B-determined antigens in the rat) is paralleled by an equally high proportion of responsive B lymphocytes. The alloantibody response of HO rats against DA antigens was measured by haemagglutination, lymphocyte cytotoxicity, and by use of a labeled rabbit anti-rat Fab to measure the total antibody bound to allogeneic erythrocytes. It was found that: (1) In response to graded doses of F1 hybrid lymph node cells i.v., the highest antibody titres were elicited by 3 X 106 cells. (2) The alloantibody response was markedly thymus-dependent. (3) An (HO X DA)F1n skin graft primed an HO recipient to give a mucli higher antibody response to a second graft than to the first graft. (4) The highest serum concentration of alloantibody obtainable was less than the concentration of specific antibody produced in response to a suboptimal dose of sheep erythrocytes. On the basis of this and other evidence, a case is made that the frequency of B lymphocytes responsive to Ag-B antigens is probably not exceptional; T lymphocytes are uniquely “alloagressive.”