UNEXPECTED LYMPHO‐CYTOTOXIC REACTIONS OF ANTI‐H‐2 SERA ON NORMAL LYMPH‐NODE CELLS: ARE THEY DUE TO ALTERED H‐2 STRUCTURES OR ANTI‐VIRAL ANTIBODIES?

Summary When testing the serum of an individual anti-H-2 immunized mouse (B10 x A.SW)F1 anti-B10.M by the routine micro-lymphocytotoxicity test on lymph-node cells, unexpected antibodies were found. The most striking finding was that after absorption of anti-H-2.8 antibodies with B10.A(2R) (Kk) cells, antibodies remained which reacted with AKR, B10.AKM and B10.A V + mice while B10.A V-, B10.BR and C3H mice were negative. While all these strains share the Kk allele, only the positively reacting strains express high titres of infectious RNA turnover viruses. Unexpected reactions were observed also with H-2d, H-2j and H-2r cells and absorption experiments indicated two or three antibody populations. These reactions could be interpreted by two different possibilities: (1) anti-H-2 antibodies react with virus-altered H-2 structures; and (2) antiviral antibodies react with H-2 structures complexed with viruses. These possibilities should be taken into account when H-2 sera are tested on tumour or virus-infected cells.