The formaldehyde stability of thymocyte immunogens.

The differential effect of formaldehyde on mouse thymic and erythrocyte immunogens is studied using a simple technique. Changes are reflected in the antibody-independent properties of rabbit antisera to these treated cells. Taken as a whole all properties are quantitatively reduced in fifteen antisera but there are some notable exceptions. The five antisera with the highest lymphocytotoxic titres, having titres equal with fresh thymocyte antisera, show detectable levels of immunosuppression. This falls significantly below the level achieved with antisera to fresh thymocytes to suggest that some relevant immunogens are susceptible and some resistant to formaldehyde; the latter alone perhaps determine lymphocytotoxicity.