Section 11 — Immunogenetics 



hundreds of offspring and, in some cases, 

 through several generations. The allotypes 

 appear to be determined by six genes equally 

 divided between two loci (a and b) giving a 

 maximum of nine possible and not closely 

 linked "gene pairs" on chromosomes. 



The phenotypic distribution of the allotypic 

 determinants on the y-globulin molecule and its 

 component parts will also be reported. 



11.19. Non H-2 Antigens of Mice. D. Bernard Amos 

 (Durham, U.S.A.). 



Mice of one H-2 genotype hyperimmunized 

 with tumor from another H-2 genotype produce 

 antibodies detectable as hemagglutinins and 

 cytotoxins. Most of the antibodies are directed 

 at H-2 antigens, but in certain combinations anti- 

 bodies reacting with other antigens are present. 

 An antibody produced in C57BL against 

 CsH/St tumor 6C3HED reacts with cells 

 carrying H-2 antigens C, K, H, A, but also with 

 cells from 129 mice which carry none of these. 

 The antigen on 129 was tentatively called alpha. 

 Since the antigen is a single factor controlled by 

 a gene H-5a present in C;3H/St and 129 but not in 

 CsH/He or C57BL, the designation was changed 

 to H-5A. 



Another antigen, H-6A (first designated delta), 

 is present in a different C3H subline, C3H/HC 

 but is not in C3H/SL Both antigens are hemag- 

 glutinogens. H-5A is present in quantity on 

 kidney, testes and lung; H-6A in testes, spleen, 

 lung, brain and gut. A strongly cross reactive 

 antigen is present in feces independently of the 

 H-6 genotype of the host. 



Both antisera react with other antigens not 

 related to the hemagglutinogens. One cytotoxin 

 has been found in antibody to CsH/St and a 

 mixture of several cytotoxins in antibody 

 against C^H/He. These antigens appear to 

 segregate independently of H-2, H-5 and H-6 

 and are being studied in reciprocal crosses 

 between C3H/He and C3H/SL Strains co-isogenic 

 for the various factors are being established for 

 a study of the relationship between graft rejection 

 and a variety of cytotoxic or hemagglutinating 

 antibodies. 



1 1 .20. Developmental Genetics of H-2 Antigens of the 

 Mouse. G. Hoecker, O. Pizarro and P. Ru- 

 binstein (Santiago, Chile). 



H-2 antigens of the mouse offer to be good 

 materials for the study of gene action at the 



cellular level. The H-2 locus determines a 

 complex system of tissue and red cell antigens 

 which are inherited en bloc. The H-2 locus 

 exhibits pseudoallelism, some antigens crossing- 

 over in about I per cent of the gametes. 



H-2 antigens seem to be present in very small 

 amounts — basal — in embryos and in newborn 

 mice. After birth, they increase and reach adult 

 concentration in about 5 to 6 days. During this 

 period different antigens from this system 

 increase their concentrations at the same rate and 

 reach maximum concentrations at the same time. 

 The phenotypic expression of H-2 genes is 

 strongly modified by the cellular environment 

 during development, both in quantity and 

 quality. As a result, different tissues vary in their 

 antigenic contents and some lack them alto- 

 gether. Besides these main variations in pheno- 

 typic expression, subtler changes were found: 



(1) H-2 antigens from tissues having the same 

 amounts of antigens vary greatly in their ability 

 to induce and sustain antibody production and in 

 the types of antibodies induced preferentially. 



(2) Differences in solubility of H-2 antigens in 

 saline were also found in some strains of mice 

 but not in others. 



11.21. An H-2-associated Serum Protein Variant in 

 the Mouse. D. C. Shreefler (Ann Arbor, 

 U.S.A.). 



A 20- to 25-fold difference in the concentration 

 of a specific seium a-globulin has been detected 

 among inbred mouse strains by immunodiffusion 

 with rabbit antisera. Studies of the inheritance 

 of this system and evidence suggesting associa- 

 tion with the histocompatibility-2 locus have 

 been reported. A pair of additively acting 

 alleles at an autosomal locus determine, in 

 homozygous condition, the low concentration 

 serum serological phenotype (Ss-L), or the high 

 type (Ss-H); the heterozygote has an inter- 

 mediate phenotype (Ss-HL). The Ss components 

 of Ss-H and Ss-L sera have the same apparent 

 electrophoretic mobility, precipitation behavior, 

 and pH and heat stability. No differences in 

 antigenic specificity have been detected, even 

 with specific rabbit anti-Ss serum. The Ss protein 

 is a euglobulin, probably of high molecular 

 weight, and has little or no lipid or carbohydrate 

 content. Tests for esterase, phosphatase, and 

 other enzymatic activities have been negative. 

 Present evidence strongly suggests control of the 

 Ss trait by the H-2 locus. All seven Ss-L lines 

 tested have the H-2 k allele; eleven Ss-H lines 

 surveyed have various H-2 alleles, but none has 

 H-2 k . Offspring from backcrosses of (C57BL/10 



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