[Passive enhancement of allogeneic rat kidney transplants with antibodies against nylon-adhering splenic lymphocytes].

Male BD IX rats were intraperitoneally immunized with 6.35 X 10(6) nylon adherent spleen lymphocytes from male Sprague-Dawley rats (SD). The inbred strains used are different from each other at their major histocompatibility complex. Sensitized animals were exsanguinated 2, 4, 8 and 12 days after the primary injection. After the secondary injection on day 14 the animals were exsanguinated on day 21. The BD IX recipients of (BD IX X SD) F1 renal allograft were intravenously injected with 1 ml of the antisera immediately after completion of the transplant. Significant prolongation of survival time was already obtained with the 8-day-serum pool. The absorption of antiserum with packed SD red blood cells did not affect its enhancing activity. In vitro testing of antisera by 51Cr-release assay showed the highest titer of complement depending cytotoxicity 8 days after immunization. Whilst the cytotoxic activity against nonadherent spleen cells was completely lost after twice absorption with SD erythrocytes, the cytotoxic activity against adherent spleen cells was only slightly reduced. Thus it is likely that enhancing activity of alloantiserum is attributed to anti-Ia or anti-B-cell antibodies. These antibodies were detectable 4 to 8 days after immunization with low dose nylon adherent spleen cells.