H-2 antibodies in mice 41 z Eur. J. Iinmunol. 1974.4: 41-44 zyxwvutsrq J. Klein+", S. Livnat", V. Hauptfeld', L. Jefabek' and I. Weismano* Department of Oral Biology, School of Dentistry+ and Department of Human Genetics, Medical School', The University of Michigan, Ann Arbor and Department of Pathologyn, Stanford University School of Medicine, Stanford Production of anti-H-2 antibodies in thymectomized mice Neonatally and adult thymectomized (Tx) mice of strains C57BL/ lOSn and A.BY (H-2b) were immunized at the age of 5 zyxw - 8 weeks with lethally irra- diated spleen and lymph node cells from adult B 10.A and A (H-2a) donors, respectively. The titer of H-2 hemagglutinins and cytotoxins was determined at different intervals after immunization, Both untreated antibodies and anti- bodies reduced with 2-mercaptoethanol(2-Me) were tested. The non-Tx control mice responded with production of both 2-Me-sensitive and 2-Me-resistant H-2 antibodies. In the Tx mice, only 2-Me-sensitive H-2 antibodies were detected. Thus, the anti-H-2 IgM response appears to be thymus-independent and the anti-H-2 IgC response thymus-dependent. 1. Introduction In mice, antigens capable of inducing humoral antibody responses can be broadly divided into two categories. In one category are antigens which elicit antibody formation in thymus-deprived mice* (thymus-independent antigens); in the second category are antigens which can elicit antibody response in thymus-deprived hosts, but such response is con- siderably depressed in comparison to normal animals (thymus- dependent antigens). The thymus-independent antigens appear to be distinguished by the presence of repeated structural subunits on a common backbone and may include polysaccharides zyxwvuts (e.g, pneumo- coccal polysaccharide) or proteins (e.g. polymerized flagellin) [ 1-31, Antibodies produced against thymus-independent anti- gens are of the IgM class. There is no clear evidence of a secondary response (memory) to secondary challenge with these antigens. A variety of antigens belonging to the thymus- dependent category can elicit formation of both IgM and IgC antibodies in normal mice [4, 51. Repeated challenge of such mice with the thymus-dependent antigens leads to a charac- teristic secondary response. Thymus-deprived mice, on the other hand, are unable to form a level of IgC antibodies characteristic of a secondary response zyxwvutsrqp [5]. In the present communication we attempt to answer the question of whether antigens controlled by the major histo- compatibility complex in the mouse (H-2) belong to the thymus-independent or thymus-dependent category. Thymus dependency of the cellular response to H-2 antigens was de- monstrated some time ago [6], but thymus dependency or independency of the humoral anti-H-2 response has not been - to our knowledge - studied. 2. Materials and methods 2.1. Animals Mice of strains C57BL/ 1 OSn (=B 10; H-2b), A.BY (H-2b), B1O.A (H-2a) and A/J (H-2a) were raised in the breeder colony of J. Klein at the University of Michigan. The strains, * We use the term "thymus-deprived" hosts to mean mice without functional thymuses and with a severely depleted peripheral T cell pool. * Senior Dernham Fellow of Oncology, California Division, American Cancer Society, Palo Alto, Calif. Correspondence: Jan Klein, Department of Microbiology, University of Texas Southwestern Medical School, Dallas, Texas 75235, USA Abbreviations: Tx: Thymectomized 2-Me: 2-Mercaptoethanol B10 and BlO.A, A.BY and A, are congenic and differ in the H-2 complex only. Additional strains used in the experiment are listed in Table 1. Table 1. Hemagglutination titer of B10 anti-B1O.A serum tested with panel of red blood cells Strain H-2 Subdivision Pnmarya) Tertiaryb) type shared wtth Cc) nTxC) C nTx donor BIO.A a zyxwv Kk Dd 6404) 1280 2560 5120 - <10 <10 <I0 <I0 B 10 b - BlO.D2 d - Dd 320 640 640 1280 B1O.M f - - <LO <10 <I0 <10 BlO.HTG BIO.A(1R) B lO.A(5R) B1O.WB BIO.BR B1O.AKM C3H.OH B1O.F B1O.G B1O.RIII zyxwvu (?INS) B1O.S BIQ.HTT B1O.PL - g - h Kk - i - Dd J - k Kk - m Kk - - 0 - - P - q - - <10 80 20 <10 20 <10 zyx <lO < 10 <10 <10 160 160 <10 160 I60 <lo <lo <10 r - - <I0 <10 s - - <10 <I0 t - Dd 1280 1280 640 640 u - Dd <10 <10 80 320 80 320 <10 <10 160 320 80 320 <10 <I0 80 <I0 <10 <I0 <I0 <10 160 <10 1280 5120 640 1280 <I0 <lO 160 <10 B IO.SM v - - AQR y - Dd 320 320 640 1280 a) Primary response serum tested 8 days after single injection of immunizing cells. b) Tertiary response recipients immunized 3 times, serum tested 6 days after the last injection. c) C = control, non-thymectomized mice; nTx = neonatally thymec- tomized mice. d) Reciprocal of titer. 2.2. Thymectomy Pregnant B 10 females were sent to Stanford where all neonatal thymectomies were performed by surgical extir- pation in ice-anesthesized mice. After weaning, the thymectomized (Tx) mice were returned to Ann Arbor. Adult thymectomies were performed at Ann Arbor by the suction technique, the Tx mice were lethally irradiated and saved with syngeneic bone marrow cells treated with AKR