Frequencies of background cytoplasmic ig-containing cells in various lymphoid organs of athymic asplenic (lasat), athymic, asplenic and normal balb/c mice.

The frequency of immunoglobulin-containing plasma blasts and plasma cells (C-Ig cells) was determined by means of immunofluorescence in various lymphoid organs of hereditarily athymic asplenic (lasat), athymic (nude), asplenic (all on a BALB/c background) and normal BALB/c mice. Two age groups were tested, namely 8 and 14 weeks. The total number of C-Ig cells in spleen, bone marrow, lymph nodes and Peyer's patches together was the largest in the normal BALB/c mice, the smallest in the lasat mice, and intermediate in the athymic mice and the asplenic mice. The mice of all four groups had more C-Ig cells at the age of 14 weeks than at the age of 8 weeks. In 8-week-old BALB/c mice and in athymic nude mice most C-Ig cells were located in the spleen. In lasat mice and in thymus-bearing asplenic mice the bone marrow was the major site of localization of C-Ig cells. In all four groups of mice the number of C-Ig cells increased considerably with age, especially in the bone marrow. In athymic mice, whether asplenic or not, C-Ig cell numbers in the Peyer's patches were deficient. The percentage distribution of C-IgM, C-IgG1, C-IgG2, C-IgG3 and C-IgA cells was different for different lymphoid organs, and was dependent on both the spleen and the thymus. In normal BALB/c mice C-IgM cells were the most frequent in the spleen, whereas the other classes of C-Ig cells were the most frequent in the other lymphoid organs. In absolute numbers, C-IgM cells were the most numerous in the two groups of eusplenic mice, and C-IgG and C-IgA cells in the two groups of euthymic mice.