Further studies on B-lymphocyte suppression in delayed hypersensitivity, indicating a possible mechanism for Jones-Mote hypersensitivity.

A previous report of increased intensity and prolongation of contact hypersensitivity in animals pre-treated with cyclophosphamide (CY) has been confirmed using other immunosuppressive agents. Melphalan, ICRF 159 and azathioprine caused a similar increase in contact sensitivity reactions, whereas busulphan, procarbazine and chlorambucil were inactive in this respect. The increased contact hypersensitivity was not associated with increased lymph node activity. Pre-treatment with CY, ICRF 159 and melphalan also caused increased intensity and prolonged Jones—Mote type reactions so that they resembled tuberculin-type reactions. This was associated with a marked reduction in γ antibody production. It is therefore suggested that Jones—Mote hypersensitivity is a further example of a T-lymphocyte reaction modulated by a B-lymphocyte response.