Lawrence A. Rheins

Induction of specific humoral immunity to soluble proteins in the American cockroach (Periplaneta americana): II. Nature of the secondary response

Abstract Adult male American cockroaches ( Periplaneta americana ) generated a specific protective response when injected with soluble protein toxins. This response developed over a period of time, peaking within 2 weeks and then gradually subsiding by the fifth week. Specificity of this reactivity was demonstrated by the fact that immunized animals were only protected against the original immunizing toxin, and not to a heterologous toxin. Passive transfer studies revealed that protection could be transferred to virgin animals with cell-free immune hemolymph. Thus, this advanced invertebrate is capable of generating a specific adaptive humoral immune response to these soluble proteins.

Suppression of the cutaneous immune response following topical application of the prostaglandin PGE2

UVB irradiation (290-320 nm) and topical applications of arachidonic acid (AA) in mice decrease the number of identifiable Langerhans cells and alter the cutaneous immune response. Application of contact allergens such as dinitrofluorobenzene (DNFB) to irradiated or AA-treated skin induces antigen-specific tolerance. Indomethacin (IM), a cyclooxygenase inhibitor, administered orally to mice prior to UVB irradiation or prior to the topical application of arachidonic acid, abrogates suppression of contact hypersensitivity (CHS) to DNFB. This suggests a byproduct of arachidonic acid generated through the cyclooxygenase pathway may be involved in the immune suppression. Topical application of various prostaglandins (PGE2, PGD2, PGF2 alpha, and CTXA2) did not cause alterations in the population density of the identifiable Ia+ dendritic Langerhans cells. PGE2, but no other tested agent, produced a suppression of the CHS response to DNFB. These observations suggests that of the various prostaglandins, PGE2 might be one of several biochemical signals which mediate the suppression of contact hypersensitivity reactions following ultraviolet radiation exposure. However, the mechanisms by which PGE2 produces its suppressive effects have not been identified.

Effect of gender on the inducible humoral immune response to honeybee venom in the american cockroach (Periplanetaamericana)

It is well known that in higher animals, the female of the species usually possesses a superior immune response to that of the male. We investigated the possibility that this rule of nature might also be true amongst the invertebrates. Adult female American cockroaches (Periplaneta americana) were immunized with Honeybee venom, and their responses were compared to that of the adult male. The female primary response was found not only to be enhanced, but prolonged as compared to the male. The response was also specific and demonstrated long-term immunological memory. Thus, the humoral immune response of this advanced invertebrate shares yet another characteristic common to higher vertebrates, since the female of the species demonstrated much better immune responsiveness than the male.

An inducible humoral factor in the American cockroach (Periplaneta americana): Precipitin activity that is sensitive to a proteolytic enzyme

Abstract The humoral factor induced in the American cockroach, Periplaneta americana, by the soluble protein venoms, honeybee venom (HBT) and Western cottonmouth moccasin venom (CMV), was shown to behave like a precipitating antibody-like molecule, since it formed specific precipitin bands with homologous antigen in Ouchterlony gels. In addition, the humoral factor was demonstrated to be protein in nature, since it was sensitive to the proteolytic enzyme trypsin. Hyperimmune hemolymph treated with trypsin no longer passively protected animals from the lethal effects of HBT, and lost its ability to form precipitin bands with the antigen in Ouchterlony gels.

Ontogeny of the invertebrate humoral immune response: Studies on various developmental stages of the American cockroach (Periplaneta americana)

Earlier studies revealed that a specific adaptive humoral immune response can be induced in the American cockroach (Periplaneta americana) to the soluble protein complex, Honeybee venom (HBT). We have undertaken a series of ontogenetic studies to determine if there are differences between the protective responses of roaches representing different developmental stages. Our results indicated that the response to HBT in the immature cockroach (nymphs weighing 200-500 mg) was characterized by a significant lag period before immune protection began to develop. However, by the second week of the response, reactivity was comparable to that of the adult. Old adult male roaches (animals 5 months into adulthood) displayed a significant decline in reactivity during the early phases of the response in comparison to younger adults, and in general, appeared to be less vigorous in generating protection. Both the nymph and old adult roaches demonstrated good secondary responsiveness. The results from these experiments indicated that the developmental stage of the roach could be directly correlated to the degree of immunocompetency possessed by the animal. This is similar to the ontogenetic sequence typically found for immune reactivity in vertebrates.

The humoral immune response in the american cockroach, Periplanetaamericana: Reactivity to a defined antigen from honeybee venom, phospholipase A2

Our previous experiments demonstrated that honeybee venom could induce a specific, adaptive humoral immune response in the American cockroach. Since honeybee venom is a complex substance made up of several proteins, a more defined antigen is needed for future characterization studies. One of the components of bee venom, phospholipase A2 (PA2) was found to be highly lethal and immunogenic in the roach. Roaches injected with PA2 generated a specific primary response that developed over a period of time, peaking within 10 days, and then gradually subsiding by the fifth week. Specificity of this response was demonstrated by the fact that immunized animals were protected against the original immunizing PA2, but not to PA2 from a heterologous source. In addition, a secondary response could be induced with PA2, demonstrating the existence of immunologic memory. Thus, we established that PA2 could induce as good, if not better, humoral responsiveness as whole bee venom, and therefore could be utilized as a more defined antigen in studies designed to characterize the inducible humoral factor in the roach.