Serum IgM immunoglobulin levels and antibody responses to an optimally immunogenic dose of Type III pneumococcal polysaccharide (SSS-III) were assessed for F1, F2, and backcross progeny derived from crosses between high responding BALB/cAnN (B) and low responding CBA/HN (C) mice. The results obtained confirmed our original hypothesis, namely, that a major component, present on the X chromosome, governs the ability to respond to SSS-III in a decisive manner. Although all low responding C mice had low IgM levels, both intermediate and high responders had high IgM levels of the same magnitude. Treatment with bacterial lipopolysaccharides (LPS) resulted in a significant increase in the IgM levels of low responding C mice. While the IgM levels attained were similar to those of high responding B mice, not given LPS, no antibody specific for LPS appeared to be produced. These findings suggest that C mice are unable to make an IgM antibody response to SSS-III and other polysaccharide antigens, despite the fact that they possess the capacity to synthesize normal amounts of IgM immunoglobulin.

This content is only available as a PDF.