They're both right. They are produced by the lymphoid progenitor cells of the bone marrow. T cells mature in the thymus whereas B cells migrate to the spleen and mature into B-lymphocytes.
I'm hoping someone else will verify this. I'm sure of everything except the maturation of B cells. I've seen from some sources that they actually mature in the bone marrow and from other sources that they mature in the spleen so not sure which one to follow.
I guess the maturation of B-cells is more complex than just saying the spleen, I dont know if this site is valid (University of Arizona) be the judge for your self....
" [FONT=Arial, Helvetica, sans-serif]B cells change their location with their stages of maturation, each location providing the microenvironment suitable for the B cell at that life stage. Stem cells produce lymphoid progenitors and pro-B cells in the marrow just under the bone. Developing B cells move toward the center of the marrow as they mature. Mature naive B cells leave the marrow and use
selectins to bind
addressins on blood vessel endothelium to enter peripheral lymphoid tissues, passing through T cell areas and entering the B cell areas (follicles).
Peyer's patches,
tonsils and
appendix are predominantly composed of large follicles. The microenvironment in the MALT follicles (including the T cell cytokines made there) signals the B cells to produce IgA, while that in the lymph nodes and spleen signals the B cells to make IgG..
[FONT=Arial, Helvetica, sans-serif]B cells encountering antigen and receiving appropriate T cell help in the T cell areas form
germinal centers in the follicles, where they divide rapidly, and undergo somatic hypermutation and selection for B cells with higher affinity receptors. Antibody-secreting plasma cells, short-lived ones that have not passed through the follicles and longer-lived ones that have undergone hypermutation and class switching in the follicles, are found primarily in the
medullary cords of the lymph nodes, the
red pulp of the spleen, and in the
bone marrow (primarily IgG-secreting plasma cells) or
mucosal lamina propria (IgA-secreting plasma cells).
Memory B cells are found predominantly in the marginal zone of the spleen, the sub-capsular sinus of the lymph nodes, and under the intestinal epithelium in the Peyer's patches and crypt epithelium of the tonsils; a few are also found in the blood.".
http://microvet.arizona.edu/Courses/MIC419/Tutorials/Bcelldevelopment.html
