A N T I G E N - I N D U C E D CHANGES IN LYMPHOID CELL HISTONES II. Regional Lymph Nodes

The nuclcar histones of control and antigen-affected lymphocytcs and thymocytes were measured in terms of their intensity of staining with ammoniacal-silver (A-S) and alkaline fast green (FG). Subcutaneous injection of full strength and doubly concentrated tetanus toxoid into the upper forelimb was followed by an acute decrease in the intensity of thc FG and A-S staining of the thymocyte nuclear histones. Such changes in staining werc delayed in thc nuclcar histones of the rcgional axillary lymph nodes. In contrast, the injection of a l : 100 dilution of tetanus toxoid caused an acutc decrease in staining of thc nuclei of the regional lymph node lymphocytcs but only minimal changes in the thymocytcs. An acute decrease in staining of the lymph node lymphocytes also occurred when heterologous serum proteins were used as the antigen. Prior administration of cortisonc was found to inhibit the antigcn-induced changes in thc staining of lymphocyte nuclear histones. No such inhibitions occurred after the administration of saline solution. The findings suggcst that the nuclear histoncs play a significant role in the immuno!ogical competcncc of lymphoid cells. However, additional studies are needed to define the biochemical basis of the observed changes as well as the mechanisms whereby antigen-induced changes in nuclear histones participate in the complex cellular and serological alterations which are evoked by antigens, viz. plasma cell formation and antibody synthesis. In a previous study we found that the injection of an antigen causes an acute decrease in the intensity of staining of nuclear histones of thymocytes with ammoniacal-silver (A-S) or alkaline fast green (FG) (1). The present study is principally concerned with the histones of lymphocytes of lymph nodes draining the site of an antigen injection. Observations have also been made on the action of cortisone on antigen-induced changes in the histones of lymphoid cells. M A T E R I A L S A N D M E T H O D S The present study utilized male and female CF-1 mice (Carworth Farms, New City, New York) weighing 15 to 20 gm. The principal antigen employed was tetanus toxoid (Wyeth) twice concentrated, full strength, and diluted 1:100 with sterile physiological saline. One-tenth of a milliliter of the appropriate concentration of tetanus toxoid was injected subcutaneously into the medial aspect of the upper forelimb. The injected mice were sacrificed at various times after the injection (30 minutes, 1 hour, 2 hours, and 24 hours). Smears were then prepared of the thymus gland and the ipsilateral axillary lymph nodes. In similar studies human serum and commercial preparations of 16.5 per cent solution of human gamma globulin were used as the antigen. The effect of cortisone was tested by injecting 0.1 ml (2.5 rag) of a cortisone acetate suspension into one 797 on O cber 3, 2017 jcb.rress.org D ow nladed fom