Delayed-type hypersensitivity in the mouse: Effect of vinblastine on sensitization by sheep red blood cells

Mice receiving antigen (SRBC: sheep red blood cells) and vinblastine on the same day (or the day after antigen stimulation) show greatly decreased numbers of plaque-forming cells in the spleen on the fourth day after antigenic stimulation. There is also some loss of viable splenic lymphocytes by the fourth day after immunization and vinblastine administration. The apparent delayed-type footpad swelling responses of such vinblastine- and antigen-treated mice are similar or greater than responses found in mice receiving antigen alone. The spleen cells of antigen- and "vinblastine plus antigen" -treated mice show the same amount of helper cell activity. However, mice receiving vinblastine 2 days after antigen, but 3 days prior to delayed-type hypersensitivity (DTH) testing, show diminsshed DTH responses compared to mice receiving antigen alone. There is also a loss of peripheral blood leukocytes in such mice and this vinblastine-induced depression of the DTH response probably represents some loss of effector abilities of treated mice. The interpretation of the DTH reactivity is difficult, because mice receiving vinblastine alone demonstrated an anomalous footpad swelling reaction of broad specificity that is not associated with the development of either antibody-forming cells or helper activity in the spleen of treated mice. The nature of this reaction appeared to be largely edematous and its origin at this time is not completely understood. Such reactions show no apparent infiltration of mononuclear cells, in contrast to the responses of mice immunized with sheep red blood cells or sheep red blood cells plus vinblastine. Because this anomalous reaction interferes with the quantitation of DTH reactions, it is difficult to draw conclusions concerning the effect of vinblastine on the activation of cells that mediate DTH.