Stimulation of Human Lymphocyte Subpopulations by Protein A from <i>Staphylococcus aureus</i>

Abstract

Protein A from Staphylococcus aureus is known to stimulate human lymphocytes. Using ³H-thymidine incorporation, virus plaque assay and induction of cytotoxic T lymphocytes (CTL), this study showed that soluble or insoluble protein A stimulated different lymphocyte subpopulations. Soluble protein A is highly mitogenic to T lymphocytes. In both ³H-thymidine incorporation and virus plaque assay, its maximum stimulation was as high as the stimulation by the nonspecific mitogens phytohemagglutinin and concanavalin A, and a higher CTL response than that induced by phytohemagglutinin or concanavalin A was induced. Mitogenic activity to B lymphocytes was negligible. S. aureus (Cowan I strain) is itself considered to be an insoluble form of protein A and is 3–4 times more mitogenic to B lymphocytes than pokeweed mitogen without any increase in virus plaque-forming cells. No mitogenicity was noted to T lymphocytes. Sepharose CL-4B-protein A, also known as insoluble protein A, stimulated both T and B lymphocytes effectively, but its mitogenicity to T lymphocytes was considered to be due to the soluble protein A released from the Sepharose CL-4B beads.

Induction of Cytotoxic Lymphocytes by Protein A Derived from <i>Staphylococcus aureus</i>

“…In a previous report [7], we demonstrated that pA was a good mitogen for human T lymphocytes and could induce cytotoxic lymphocytes against human LCL more effectively than PHA or Con A. pA was al so a more potent inducer of cytotoxic activity against two different human LCLs -autologous and alloge neic LCL -than PHA or Con A (table I). Thus the pAinduced cytotoxicity was nonspecific.…”

“…Thus the pAinduced cytotoxicity was nonspecific. In this case, PHA and Con A induced highly proliferative re sponses in terms of 3H-thymidine incorporation [7], The time course for the induction of pA-activated Days Fig. 1.…”

“…T lymphocytes were isolated through the formation of spon taneous rosettes with sheep erythrocytes and centrifugation on Ficoll-iothalamate solution [7], or through a Nylon fiber column [8]: briefly, IO-30x 10'' lymphocytes were loaded into a plastic syringe packed with 0.5 g of Nylon fiber. After the incubation of the syringe for 1 h at 37 °C, it was washed with 10 ml of warm medium and the effluent cells were collected.…”

“…I n an earlier study, we have demonstrated that pro tein A (pA) from Staphylococcus aureus is a good mi togen for human T lymphocytes, that it can stimulate Fc-receptor-negative [Fc(-)] T lymphocytes in 3H-thymidine incorporation, and that it can induce cyto toxic lymphocytes against a human lymphoblastoid cell line (LCL) more effectively than phytohem agglutinin (PH A) or concanavalin A [Con A;7], In this paper, we examine pA-induced cytotoxic activity in detail, using lymphocyte separation tech niques. The results show that pA-induced cytotoxicity occurs only when pA is present in the cytotoxicity as say and that it is mediated by T lymphocytes.…”

A Unique Substance from the Granary Weevil: Nonspecific Immunoglobulin Binding Substance

“…Furthermore, protein A shows some biological ac tivities such as anaphylaxis-like cutaneous and sys temic reaction in nonimmunized guinea pigs [19] and stimulation of human lymphocyte subpopulations [20,21]. However, it is still unknown whether IBS has some biological activities.…”