[Subclass distribution of human IgG antibodies to Mycoplasma pneumoniae in the course of mycoplasmosis].

The prevalence of human IgG1-IgG4 to sonicated antigen of M. pneumoniae in the 138 sera obtained from patients with mycoplasmosis was analysed. Antibodies of IgG1 were diagnosed in 47 (34.1%), IgG2 in 42 (30.4%) and IgG3 subclass in 58 (42.0%) serum samples. The concentration of IgG4 was below detection level. Generally, the frequency of occurrence of IgG2 antibodies increased with age reaching its peak among adults. On the other hand IgG1 and IgG3 for M. pneumoniae were diagnosed more often in serum samples obtained from children than from adults. We did not find any essential changes in the pattern of IgG subclass during the course of infection however it seems that the level of IgG3 antibodies decreased faster than IgG1 which may be caused by the fact that the IgG3 antibodies have a much shorter half-life in comparison to the IgG1.