STUDIES ON GLOBULIN AND ANTIBODY PRODUCTION IN MICE THYMECTOMIZED AT BIRTH

Abstract

Serum globulin levels and antibody against sheep red cells, Salmonella typhi (`O' and `H'), haemocyanin and pneumococcus type 3 capsular polysacharide (SSS III) were studied in C3H/Bi and C57BL×C3H/Bi F₁ hybrid mice thymectomized within 18 hours of birth. Thymectomized mice tend to recover more slowly than intact mice from the physiological hypo-γ-globulinaemia present 3–4 weeks after birth, but the majority of mice that survived beyond 6 weeks had serum globulin levels comparable to those in intact animals. Increased γ_1A-globulin levels were observed in some thymectomized mice which survived for 7 weeks or more and the immuno-electrophoretic patterns sometimes resembled those seen in mice with γ_1A myelomas. Macroglobulin (γ_1M) was detected in the sera of thymectomized mice which contained normal amounts of γ-globulin.

Total serum protein levels of groups of thymectomized and intact mice were not significantly different. The turnover rate of plasma albumin was also closely similar in both groups, but that of γ-globulin was accelerated in most of the thymectomized mice examined.

Antibodies against SSS III, sheep red cell agglutinins and typhoid `H' agglutinins behaved as 7S globulins, in contrast with sheep red cell haemolysins which belonged to the 19S group.

Antibody levels following primary stimulation with sheep red cells and Salmonella antigens were usually, but not always, much lower in thymectomized mice than in intact control mice. However antibody levels against haemocyanin and SSS III were within the range of controls in more than half the thymectomized mice. Few thymectomized mice after stimulation with a mixture of three antigens failed to give a detectable antibody response to all the antigens, and some responded as well as did intact mice.

The significance of these findings is discussed in relation to current theories of the function of the thymus in the development of immune responses.

Many of the older thymectomized mice showed a characteristic wasting syndrome, but it is unlikely that a general failure of antibody response can account for this. Evidence for the presence of auto-antibodies against red cells or nuclear or cytoplasmic constituents was sought but was not found.