Changes in macrophages in vivo induced by desensitization

Hyposensitization to urushiol among Japanese lacquer craftsmen: results of patch tests on students learning the art of lacquerware

8 subjects learning the art of lacquerware were patch tested to urushiol before and after contact with lacquer, in order to document whether hyposensitization to urushiol occurred among Japanese lacquer craftsmen. Simultaneously, we performed patch tests on 2 urushiol-sensitized controls who had no contact with lacquer during the investigation. Lacquer is made from the sap of the Japanese lacquer tree and raw lacquer is composed of 60-65% urushiol and its oligomer. 5 of the 8 subjects showed positive reactions to urushiol 1 month after their first contact. They became negative or less positive after prolonged (9 or 10 months) exposure to lacquer. As reactions to urushiol decreased, dermatitis became less severe. Controls showed consistently high reactions. However, 1 subject showed persistently strong reactions to urushiol. Unlike the other 7 subjects, he was previously sensitized to urushiol before the first contact with lacquer. The remaining 2 subjects showed no reaction throughout our investigation. These results strongly suggest that hyposensitization to urushiol does occur among Japanese lacquer craftsmen.

Desensitization of contact allergy to DNFB in mice. III. Characteristics of immediate desensitization induced by haptenated spleen cells

The immediate effects and mechanisms of desensitization of contact sensitivity to dinitrofluorobenzene (DNFB) were investigated. Intravenous injection of dinitrophenol (DNP)-labeled syngeneic spleen cells caused significant antigen-specific inhibition (greater than 40%) of the contact response within 24 hr in mice that had been sensitized 2 weeks prior to desensitization. With low concentrations of the hapten used for labeling, allogeneic spleen cells were found to be more efficient than syngeneic ones in inducing the down-regulation of the contact response. The most efficient desensitization was produced by DNP-cells that differed from the recipient at the MLS locus. Haptenated spleen cells induced the production of suppressor mechanisms, as spleen cells from animals desensitized with DNP-cells were able to down-regulate recipients in adoptive transfer and could block the passive transfer of contact sensitivity. Procedures that interfere with the development of suppressor cells, e.g., cyclophosphamide and adult thymectomy, interfered with desensitization by DNP-cells. These results are in contrast to desensitization with soluble dinitrobenzenesulfonic acid (DNBS), where suppressor mechanisms have not been shown. The mechanisms for desensitization depend upon the form of the desensitizing antigen.

Mechanism of densensitization in DNCB-contact sensitive guinea pigs

Contact sensitivity to dinitrochlorobenzene (DNCB) in guinea pigs could be rapidly suppressed by intravenous injection of dinitrobenzene sulfonic acid sodium salt (DNBSO3). This suppression is transient and antigen-specific. Macrophages from desensitized animals are not inactivated as shown by their ability to react, both in vivo and in vitro to lymphokines produced in a separate system. Therefore, effector lymphocytes are considered the target for the desensitizing antigen. Using an adoptive transfer system it was demonstrated that effector lymphocytes are inactivated by a direct effect of the hapten. Since this inactivation can be reversed by trypsin treatment, a receptor blockade of effector lymphocytes is proposed as the mechanism of desensitization of DNCB-contact sensitive guinea pigs. This does not exclude the possibility that additional mechanisms such as suppressor cells, compartmentalization or endogenous proliferation of lymph node lymphocytes may play an additional role.