Ig Production with Experiment of LTβR Deficient Mice

So in humans, or in the mammals, there are several structures like Payer’s patches, spleen, or lymph nodes or which are categorized as the secondary lymphoid tissues which contain the naive B cells. That means lymph nodes, spleen, and Peyer’s patches are placed where antigen-specific immune responses are induced including antibody productions. So we next wanted to know which places, lymph nodes, spleen, or Peyer’s patches are involved in producing maternal IgA antibodies in the mammary gland. So, this is a mouse. In mice, like humans, there are several lymph nodes, and of course, in the gut, Peyer’s patches develop and of course, they have spleens. To address the importance of secondary lymphoid tissues, we sometimes use this special mouse model named LTβR knockout mice.

Because LTβ is essential receptors for the development of secondary lymphoid tissues except spleen. So these mice do develop spleen, but these mice do not develop all lymph nodes and all Payer’s patches. Then we made these LTβR knockout mice to get babies in order to understand the maternal IgA antibody productions. So we collected mammary gland tissues from LTβR knockout mice, or from wild type mice. Then we performed the flow cytometric analysis again in order to look at the IgA producing plasma cells in the tissues in the mammary gland.

So in the wild-type mice, as I already told you, two weeks after parturition a very high number of IgA producing, IgA positive, B220 negative cells they can be detected in the mammary gland. However, LTβ knockout mice, even if they get babies, and then they make milk protein but when you analyze maternal IgA antibodies producing cells, you don’t detect any IgA producing plasma cells in the mammary gland two weeks after parturition. Meaning that, if you lack lymph nodes or Peyer’s patches you cannot make maternal IgA antibodies in the mammary gland. Consistent with the number of the IgA producing plasma cells in the mammary gland, if you look at the concentration milk IgA, the data is very similar.

Because LTβ receptor knockout mice, they don’t produce any IgA antibodies in milk meaning that they can produce milk, but they cannot produce maternal IgA antibodies. So milk doesn’t contain any maternal IgA antibodies in LTβR knockout mice. So these data indicated that lymph nodes or Peyer’s patches are important tissues for producing maternal IgA producing plasma cells that are recruited, that are infiltrated into the mammary gland tissues.