Effects of various drugs on insulin antibodies.

1. Insulin antibodies were induced in young guinea-pigs of both sexes weighing 300-400 g and housed in a room maintained at 28 degrees C+/-2 degrees C, by subcutaneous injection of 2 ml of freshly prepared insulin antigen emulsion between the shoulders once every month.2. To estimate the titre of serum antibody the serum was incubated with a known concentration of insulin for 90 min at 37 degrees C and the insulin not bound to antibody was estimated by the rat hemidiaphragm method.3. No significant (P>0.5) development of insulin antibody could be detected in the serum samples collected 1 month after the first and 15 days after the second monthly injections in groups of ten male guinea-pigs and six female guinea-pigs. However, the titre of insulin antibody in the serum of these groups of guinea-pigs 15 days after the third monthly injection of insulin antigen emulsion was significantly (P<0.01) raised. There was no further increase in the titre of insulin antibody in the sera 15 days after the fourth and fifth monthly injections of insulin antigen emulsion. Thus the peak titre was reached 15 days after the third monthly injection of the antigen.4. Two groups of ten male guinea-pigs each received testosterone propionate or diethylstilboestrol daily for 1 week after each monthly injection of insulin antigen emulsion. Two other groups of six female guinea-pigs each received testosterone propionate or diethylstilboestrol in a similar manner. One more group of ten female guinea-pigs received both sex hormones for 1 week after each monthly injection of insulin antigen emulsion. Testosterone facilitated the induction of insulin antibody in the serum of males but did not affect the antibody titre in the female guinea-pigs. Diethylstilboestrol facilitated the induction of insulin antibody in the serum of groups of either sex, the peak titre being attained after the second monthly injection of insulin antigen emulsion. The response of the females which received both sex hormones was similar to that of females which received diethylstilboestrol alone.5. Fifteen days after the third monthly injection of insulin antigen emulsion a group of ten guinea-pigs received hydrocortisone subcutaneously each day for 1 month. The serum antibody titre was estimated at the end of the drug treatment, and was significantly (P<0.01) reduced.6. Fifteen days after the third monthly injection of insulin antigen emulsion three different groups of five-six guinea-pigs each received tolbutamide, chlorpropamide or phenformin orally every day for a month. Antibody titres of the serum were estimated at the end of this period; there was no significant (P>0.05) reduction in groups receiving chlorpropamide or phenformin, but the serum antibody titre of the group receiving tolbutamide was significantly (P<0.01) raised.7. Fifteen days after the third monthly injection of insulin antigen emulsion different groups of five-six guinea-pigs received one of the following: 5-bromouracil, 5-fluorouracil, 6-mercaptopurine, methotrexate, 6-azauridine, busulphan, chlorambucil, cyclophosphamide, actinomycin-D or mytomycin-C intraperitoneally each day for 5 days. The serum antibody titre of all the groups of guinea-pigs was significantly (P<0.01) reduced. On the other hand the serum antibody titre of a control group of six guinea-pigs receiving normal saline intraperitoneally each day for 5 days was not significantly (P>0.5) affected.