Use of freeze-dried sensitized erythrocytes in indirect hemagglutination test for serodiagnosis of leptospirosis.

The indirect hemagglutination (HA) test using freeze-dried tanned formalinized sheep erythrocytes sensitized with deoxycholate-extracted leptospiral antigen was investigated for its applicability to serodiagnosis of leptospirosis. The sensitized erythrocytes suspension containing an adequate concentration of glycine was lyophilized and used for the HA test. The lyophilized sensitized cells are rehydrated after at least 10 months storage without any loss of HA titer. The sensitivity of such cell suspension tested on sera from cases of leptospirosis equals that of the suspension before freeze-drying.