Appendix and M-antibody formation. II. Distribution of antibody-forming cells after injection of bovine globulin in irradiated, appendix-shielded rabbits

Mononuclear and IgA-containing cells in the lacrimal gland of germ-free and conventional rats

Mononuclear cells in the lacrimal (exorbital) glands of five germ-free, five ex-germ-free, and five age-matched conventional rats were counted by light microscopy. Tissues from these rats were also examined by electron microscopy. IgA-containing plasma cells were counted by immunofluorescence microscopy in the lacrimal glands of five germ-free and five conventional rats. The median number (and range) of mononuclear cells per ten high-power fields was 25 (14-28) in germ-free rats, 33 (32-43) in ex-germ-free rats, and 41 (36-50) in conventional rats. The median number (and range) of IgA-containing plasma cells per ten high-power fields was two (0-5) in germ-free and 44 (29-72) in conventional rats. The differences in the numbers of mononuclear cells in the lacrimal glands of germ-free as compared with ex-germ-free and with conventional rats were statistically significant (P less than 0.004). The difference between the numbers of IgA-containing plasma cells in germ-free as compared with conventional rats was also statistically significant (P less than 0.004). Electron microscopy revealed that the mononuclear cells in all groups of rats consisted of macrophages and lymphocytes. These observations suggest that the number of mononuclear cells, and particularly IgA-containing plasma cells, in the rat lacrimal gland can be increased by systemic and/or local immunologic stimulation.

Germinal centres and the B cell system. IV. Functional characteristics of rabbit appendix germinal centre (-derived) cells

Functional capacities of rabbit appendix germinal centre cells were tested in appendectomized, 450 rads X-irradiated rabbits, reconstituted with autologous appendix germinal centre cells, which are obtained by mechanical separation--"stripping"--of the appendix. For comparison, functional capacities of appendix germinal centre derived cells were tested in rabbits, 450 rads X-irradiated with the appendix shielded. In both types of experimental systems, slow restoration of primary IgM responsiveness to Salmonella Java paratyphi-B (PAR) was observed; in contrast, the capacity for memory cell production (of both mu and gamma-type) to PAR was restored very early in both systems. These results suggest germinal centres to be antigen dependent microenvironments for selective as well as non-selective amplification of immature B cells, which after subsequent maturation become part of the pool of either memory or virgin mature B cells respectively.

An ultrastructure study on antibody production of the lymph nodes of rats with special reference to the role of germinal centers

Antibody-containing cells in lymph nodes, expecially in germinal centers, and in thoracic duct of rats sensitized by injection of horseradish peroxidase were studied with the immunoperoxidase method. In the primary response the large germinal center cells began to produce antibody on the 9th day and predominated thereafter in germinal centers ,added by intercellular antibody deposition in its late stage. The "ordinary" medium-sized germinal center cells were a minor component. In the secondary response, the intracellular antibody positivity disappeared immediately after the antigenic rechallenge but reappeared from 6 hours later in the large germinal center cells which further transformed from 48 to 72 hours into the "specifically differentiated" medium-sized germinal center cells that disappeared by 96 hours after the secondary injection to enter the thoracic duct. Antibody-containing cells outside the germinal centers appeared 5 to 6 days after the primary injection and were mainly comprised of plasmocytic cell series which was classified into interfollicular large cells, proplasmocytes and plasmocytes. Some results conflicting with the cytological identity of both cell series were presented.

Immunoglobulins and blood vessels in the tonsillar crypt epithelium

The localization of IgA, IgG, IgM, SP and the relationships of plasma cells and lymphocytes to blood vessels in the tonsillar crypt epithelium were investigated. Immunofluorescent techniques were used that included antisera specific for the two antigenic determinants of external secretory IgA, namely, 4s SP and 7s IgA, and also antisera specific for 7s IgG and 19s IgM. The secretory piece was absent in the crypt epithelium and in most of the crypt lumen. Aggregations of plasmacyte series cells, containing either IgG, IgA, or IgM were present in the crypt epithelium. Mature plasma cells of these aggregations abutted against the walls of blood sinusoids located in the epithelium, which suggested secretion into these sinusoids. All three immunoglobulins were also identified between epithelial cells and small lymphocytes. Postcapillary venules with emigrating small lymphocytes abounded in sub-epithelial sites, and were present at the lower border zone of the epithelium. Lymphocytes in shapes of diapedesis were observed in the endothelium of epithelial blood sinusoids. These observations are in accord with the hypothesis that a “circulation” of many lymphocytes occurs in the epithelium facilitating the activation of any one genetically committed lymphocyte.