Antigens in immunity. XV. Ultrastructural features of antigen capture in primary and secondary lymphoid follicles.

This paper describes the trapping of antigen in lymphoid follicles of rat popliteal lymph nodes as revealed by electron microscopic radioautographs following injection of (125)I-labeled Salmonella adelaide flagella and other materials. The antigen was taken up vigorously, and to an approximately equal extent, by both primary and secondary follicles. The rate of uptake was faster in preimmunized than in virgin adult rats.

Ontogeny of the immune response. I. The development of the follicular antigen-trapping mechanism.

Polymerized flagellin from Salmonella adelaide was labeled with I(125) and injected into rats varying in age from 0 to 42 days. Lymphoid organs were removed at various intervals and the progressive development of antigen-capturing structures was studied using autoradiography. The chief findings were as follows: 1.

Phylogenetic studies on the immune response. I. Localization of antigens and immune response in the toad, Bufo marinus.

Toads of the species were injected subcutaneously with I-labelled flagella from . Observations were made on the ensuing serum antibody response, the antigen localization pattern and sequential cellular changes in lymphatic and other tissues. The serum antibody findings confirmed the work of previous investigators in showing a good primary response, prolonged synthesis of mercaptoethanol sensitive antibody and little or no evidence of secondary responsiveness.

Antigens in immunity. 8. Localization of 125-I-labelled antigens in the secondary response.

Two flagellar antigens, intact flagella and monomeric flagellin from were labelled with I by the Chloramine-T method. They were injected into the hind foot-pads of rats, and the localization in the draining lymph nodes was studied by scintillation counting and autoradiography. Injected rats belonged to one of four groups: normal, unimmunized adult rats (NI); rats that had been given an unrelated antigen 6 weeks previously (HI); rats that had been given a priming dose of the same antigen (though unlabelled) 6 weeks previously (AI); and rats that had been given passive antibody by intraperitoneal injection (PI).

Antigens in immunity. VII. Analysis of immunological memory.

Rats were given primary and secondary injections in saline solution without adjuvants, of flagellar antigens, the dose varying from 10 pg (10g) to 1 mg. Rats were bled at various times after injection, and levels of both total (7S+19S) and mercaptoethanol resistant (7S) anti-H antibody were determined, using a serial two-fold dilution assay. The data from several thousand such titrations was entered on IBM punched cards and a series of programs were written to allow computer analysis thereof.

ANTIGENS IN IMMUNITY. IX. THE ANTIGEN CONTENT OF SINGLE ANTIBODY-FORMING CELLS.

Flagellar antigens from S. adelaide bacteria were labelled with carrier-free (125)I so as to achieve a substitution rate of 0.1 to 2.

ANTIGENS IN IMMUNITY. VI. THE PHAGOCYTIC RETICULUM OF LYMPH NODE FOLLICLES.

The localization of antigen in primary follicles and germinal centers of rat popliteal lymph nodes described previously using I(125)- and I(125)-labeled antigen has been confirmed by direct staining with fluorescent antibodies. A fine web of phagocytic reticulum in primary follicles was found to be responsible for antigen localization in this area. The nature of this web was confirmed by studies of the localization of colloidal carbon.