An aberrant subclass pattern of HIV-specific immunoglobulin G in sera from haemophiliacs.

The immunoglobulin (lg) G subclass response against HIV was investigated in sera from 13 haemophiliacs and 21 non-haemophiliacs. Monoclonal antibodies specific for the human lgG subclasses were used in an enzyme immunoblot assay, which was evaluated densitometrically. Seven of the haemophiliacs had detectable lgG4 antibodies to p24, a pattern which was found in only one of the sera from the non-haemophiliacs (P = 0.0022). This observation could partly be explained by a longer duration of the HIV infection in the subjects with lgG4 antibodies to HIV. No connection was found between frequency of administration of blood products and presence of HIV-specific lgG4.