Serum immunoglobulin levels in mice. Determination of the low IgA level in AKR mice by an irradiation-resistant factor.

A comparison was made between the serum immunoglobulin (Ig) levels in H-2 compatible AKR and C3H mice. The IgG1 and especially the IgA level in preleukemic AKR mice was much lower than in age-matched C3H mice, while the IgM concentration was hardly different for AKR and C3H. Lethally irradiated AKR and C3H mice reconstituted with syngeneic bone marrow (BM) cells showed a return to serum Ig levels which are normal for these strains. In AKR mice reconstituted with C3H BM cells low IgA levels were observed. On the other hand, in C3H mice reconstituted with AKR BM cells high quantities of IgA appeared, showing the AKR allotype. It is concluded that the low serum IgA concentration in AKR mice is not a reflection of a genetically determined inability of the B cell line to produce IgA, but rather a manifestation of a genetically determined capability to prevent IgA synthesis.