Research in cell-engendered immunity until recently is concerned not

Research in cell-engendered immunity until recently is concerned not only with the development of new and better vaccines alone, but also with the problem of transplanting tissues and organs from one organism to another, for although circulating antibodies play a part in the rejection of transplanted tissues, cell-engendered reactions play the primary role


A. Research in cell-engendered immunity until recently is concerned not only with the development of new and better vaccines alone , but also with the problem of transplanting tissues and organs from one organism to another, for although circulating antibodies play a part in the rejection of transplanted tissues, cell-engendered reactions play the primary role

B. Research in cell- engendered immunity until not long ago is concerned with not only the development of new and better vaccines alone, but also with the problem of transplanting tissues and organs from one organism to another, for although circulating antibodies play a part in the rejection of transplanted tissues, cell-engendered reactions play the primary role

C Research in cell- engendered immunity has been concerned until recently not only with the development of new and better vaccines, but also with the problem of transplanting tissues and organs from one organism to another, for although circulating antibodies play a part in the rejection of transplanted tissues, cell-engendered reactions play the primary role

D Recent research in cell- engendered immunity is not only concerned with the development of new and better vaccines, but also with the problem of transplanting tissues and organs from one organism to another, for in the rejection of transplanted tissues, although circulating antibodies play a part, cell-involving reactions play the primary role

E Recent research in cell-engendered immunity has been concerned not with the development of new and better vaccines, but with the problem of transplanting tissues and organs from one organism to another, for although circulating antibodies play a part in the rejection of transplanted tissues, cell-involving reactions play the primary role,