Genetic linkage between serum levels of the third component of complement and the H-2 complex

AKR/J (H-2kk) mice have higher serum C3 levels than DBA/2J (H-2dd). The F1 hybrids have intermediate levels. Analysis of the progeny of backcrosses at 21 days of age shows that C3 levels in mice of H-2dk type are significantly higher than those with H-2dd type and lower than those with H-2kk type. In addition, mice of H-2kk, H-2dk, and H-2dd types have C3 levels not significantly different from those of AKR/J, AKD2F1, and DBA/2J respectively. These findings demonstrate linkage between a gene controlling C3 levels and the H-2 complex.

Effects of cortisone on H-2 agglutinin response in normal and thymectomized adult mice

Cortisone suppresses circulating H-2 agglutinins when given prior to the injection of soluble cell extracts but not when the same antigens are given as cells. This same difference in antigen handling is observed in adult cortisone-treated thymectomized mice. Thus thymus as such is not involved in these differences in antigen handling. The spleen of adult thymectomized mice is as sensitive to cortisone as that of intact or sham-operated animals: after a strong initial drop in weight, the spleen recovers even during cortisone treatment in both intact and thymectomized mice. When a second cortisone treatment is given, the spleen loses about the same weight fraction as the first time in thymectomized and intact mice. These findings indicate that a fraction of either thymus or marrow-dependent lymphocytes differentiates in the spleen to become cortisone-sensitive. All these facts taken together show that antigen size per se is the main determining factor in antigen processing, i.e. the cellular path involved in antibody production.

Lack of correlation between the effects of cortisone on mouse spleen plaque-forming cells and circulating anti-sheep red blood cell haemolysins

The effect of 5.5 mg of cortisone acetate given to adult mice 1 day prior to the injection of 4 × 10⁸ sheep erythrocytes was studied. This drug is able to suppress more than 95 per cent of splenic plaque-forming cells (PFC) compared with immunized animals not treated with cortisone. However, the anti-sheep red cell haemolytic titre in the blood was not affected. Several hypotheses to explain this paradox were tested experimentally.

Plaque-forming cells in the bone-marrow of cortisone-treated mice, instead of being suppressed, increased to more than ten times their number compared with the controlled animals.